What is Normative Necessity?1

Gideon Rosen

September 2014

1. The Least Controversial Thesis in Metaethics

You are reading this paper now, and that’s OK. Inreading this paper you do nothing wrong. Of course your actcould have been wrong. If you had made a solemn promise notto read this paper, or if reading it might have haddisastrous consequences, then it would have been wrong foryou to read it. The fact that your act is permissible isthus at best a contingent truth.

And yet we are powerfully inclined to think that in thevicinity of this and every other contingent moral truththere lies a moral truth that holds of absolute necessity.Call your act A and let D (A) be a complete specification ofits natural, non-normative features. D(A) specifies A’sintrinsic nature, its causes and effects, the intentionswith which it was done, and so on, insofar as these can be

1 I am grateful to audiences at Columbia University, the University of Texas, Austin, the University of Nebraska, NYU, and the Chapel Hill Metaethics Workshop for their constructive incredulity. Thanks in particular to Aaron Bronfman, John Collins, Janice Dowell, Jamie Dreier, Kit Fine, Reina Hayaki, Thomas Hofweber, Paul Horwich, Jennan Ismael, Philip Kitcher, Isaac Levi, Tristram McPherson, Joe Mendola, Kate Nolfi, Ian Rumfitt, Geoff Sayre-McCord, David Sosa, Mark van Roojen, and David Velleman.

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specified in wholly non-normative terms.2 Now consider theconditional:

(1) If D(A) then A is morally permissible.

Almost everyone who has considered the question agrees thatpropositions of this sort are necessarily true if true atall. Fix the non-normative features of an act — or any itemwhatsoever — and you thereby fix its moral features as amatter of absolute, metaphysical necessity.

This is a consequence of the least controversial thesisin metaethics:

Strong Supervenience: If two possible entities arealike in every non-normative respect, they are alike inevery normative respect.

The necessity of (1) is also a consequence of acompelling view of the structure of normative reality. Onthis view, whenever a particular act has a normativefeature, there is always an explanation of this fact thatcites non-normative features of the act together with ageneral principle according to which acts with those naturalfeatures must always possess the normative feature in2 I assume a distinction between normative properties and relations on the one hand and wholly non-normative properties and relations on the other, with morally permissibilityas paradigmatically normative and the properties and relations of physics as paradigmatically non-normative. I leave it open how that line is to be drawn. I assume that propositions are structured entities, built from objects, relations, connectives and the rest roughly as a sentence isbuilt from words. A proposition is normative if it has a normative constituent. A fact is a true proposition, so a normative fact is a true proposition with a normative constituent. When I speak of non-normative “descriptions” of acts, these should be understood as structured propositions involving the act and any number of wholly non-normative constituents.

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question. This general principle may in turn be explainedby further principles, perhaps together with contingentnatural facts. But in the end we reach bedrock with a classof normative principles that cannot be explained by deeperprinciples. These are the pure and underived principles ofethics: the holy grails of pure moral theory. This viewentails the absolute necessity of conditionals like (1)provided we also accept

The Non-Contingency of Pure Moral Principles: Thebasic explanatory principles of ethics aremetaphysically necessary.

This picture is more controversial than Supervenienceitself, since philosophers sometimes deny the existence ofexceptionless explanatory principles of the envisionedsort.3 And yet even these “metaphysical particularists”would presumably agree that if there were moral principlesof the sort moral theorists generally hope to find, theywould hold of metaphysical necessity.

My first aim in this paper is to suggest thatSupervenience and Non-Contingency should both be morecontroversial than they are. Fine (2002) has argued against3 The debate over particularism is mainly a debate over theexistence of snappy moral principles that hold without exception, but which are also sufficiently accessible and tractable to play a role in moral practice. Moderate particularists reject such principles but concede that whenan act is (say) wrong, there is always some explanation of this fact that cites only natural features of the act together with a general, though perhaps infinitely complex, conditional connecting those features to normative features.The metaphysical particularist denies even this, holding that singular normative facts of the form A is N are sometimes brute. I assume that moderate particularists regard the highly specific principles they posit as necessary truths, and so accept Non-Contingency. The metaphysical particularist may be a fictional character.

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these claims, and his position is worth taking veryseriously. My larger goal, however, is to articulate thetruth in the vicinity of Supervenience and Non-Contingency.As Fine notes (2002, §4), even if moral principles do nothold of absolute necessity, they must be necessary in asense. It was no accident that your act A was permissiblegiven that it had the non-normative features it had. Any actwith those features would have been permissible — would havehad to be permissible — even if there are remotemetaphysically possible worlds in which such acts are wrong.On the replacement view advanced by Fine, basic moralprinciples and fact-norm conditionals4 like (1) enjoy a suigeneris modal status: they are normatively, though notmetaphysically, necessary. The larger aim of this paper is toprovide an account of this notion: to say what it is for aproposition to hold of normative necessity, and to explainwhy pure moral principles are necessary in this sense.

2. Against Supervenience

Long experience has taught me that contemporaryphilosophers will reflexively construe any argument againstsupervenience as a reductio of its premises. So before Ipresent such an argument, (basically Fine’s) a softening upexercise is in order: — a few words to blunt, if onlytemporarily, the impulse to regard supervenience as anunrevisable fixed point in metaethics.

The first thing to say is that Supervenience is not acommonsensical view — at least not in any literal sense.The man on the street has never heard of it and cannotunderstand the terms in which it is stated. What’s more, aswe will see, there is no sense in which ordinary moral4 This label is shorthand and should not mislead. I assume moral/normative realism in what follows, so for me normativestatements are fully factual in every sense. A so-called “fact”-norm conditional is a conditional whose antecedent specifies the wholly non-normative facts (or features of some particular act) in complete detail and whose consequent is normative.

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practice assumes or presupposes Strong Supervenience. (Weaksupervenience is another matter.) So the principle cannotderive its presumptive authority from this source. StrongSupervenience rather functions in recent philosophy as atechnical axiom: an esoteric principle which, despite itsesoteric character, strikes everyone (or almost everyone)who understands it as just plain obvious.

Confronted with a claim of this sort, it can beinstructive to stage an encounter with a clear-headedinterlocutor who does not find the proposition obvious. Soconsider the impeccably trained and thoroughly acculturatedProfessor Z. She takes in your innocuous act A with itscomplete non-normative profile D(A) and judges correctlythat A is permissible. But when invited to pronounce on themodal status of the conditional D(A) A, she saysemphatically: “This is clearly a contingent truth.” Zconcedes that she can’t readily imagine a situation in whichan act with just those features is wrong. But so what?Normative features like moral permissibility are invisible,so of course we can’t picture a moral difference without somefurther difference.5 She is more impressed by the fact thatshe can easily conceive a situation that falsifies theconditional. As she pus it:

Consider a world w that is just like the actual worldin non-normative respects but in which ActUtilitarianism is true. Your act A would have beenwrong if w had been actual. After all, no matter howmuch benefit the world derives from your scrutiny ofthis paper, you would have done more good lickingstamps for Oxfam instead. So we have a world w inwhich D(A) is true and A is wrong. Together with the

5 Compare the invitation to picture a difference in objective, single-case probabilities without a difference inthe non-probabilistic facts. However difficult this may be,it has no tendency to show that the probability facts supervene on the rest.

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actual world — where D(A) is true and A is not wrong —this yields a counterexample to supervenience.6

How to reply? It is no use denying that there is sucha world as w. For present purposes, a world is not anotherphysical universe. It is a class of propositions orsomething of the sort: a maximal consistent world-description.7 D(A) is, or corresponds to, a class ofpropositions: the non-normative propositions that are infact true. If we pretend — just for simplicity — that moralpermissibility and impermissibility are the only normativeproperties on the scene, the logical closure of D(A) and ActUtilitarianism (AU) is a world: a class of propositionsthat specifies the non-normative facts in complete detailand then assigns a normative status to every act.

So the question is not whether w is a world. Thequestion is whether w is a metaphysically possible world.Professor Z thinks it is because it strikes her as possible,and also because it shows all the marks of possibility. wis logically consistent. It is also analytically andconceptually consistent in any reasonable sense of theseterms. After all, some philosophers believe that w isactual, and however misguided these utilitarians may be,their mistake does not smack of linguistic or conceptualincompetence. Moreover, we can reason smoothly about howthings would have been had w been actual without tyingourselves up in any of the knots we encounter when we try toreason about how things would have been if Hobbes hadsquared the circle or if Fred had been a married bachelor.As she reflects, Professor Z can see no obstacle to thepossibility of w, no reason why things could not have beenas w says they are, and she cannot see how there could be

6 Since AU is presumably incompatible with the actual moral principles, we also have a counterexample to the Non-Contingency of Moral Principles.

7 See Kment (2014, ch. 4) for a version of the conception ofworlds I take for granted.

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such an obstacle. So she concludes that w is possibleafter all.

Of course Z knows that all of this is a fallible guideto possibility. Let H be a hydrogen atom and let D(H) be acomplete description of H at the level of elementaryparticles — quarks and electrons, etc. Now consider a worldw* that includes D(H) together with the proposition that His a lithium atom. This world is logically and analyticallyconsistent, and a chemical ignoramus might be able to reasonsmoothly about how things would have been had w* beenactual. But w* is not metaphysically possible, and we knowwhy. It lies in the nature of lithium that lithium atomshave three protons. H has only one. So w* is impossible— despite its apparent consistency — because it isinconsistent with an essential truth (Fine 1994a).

Professor Z should therefore be open to the followingline of thought:

You think w is genuinely possible, but that’s onlybecause you don’t know enough about the essences ofthings. If you knew more, you would see that an actwith non-normative features D(A) could not possiblyhave been wrong, and that AU could not possibly havebeen true (the natural facts being as they are).

And so she is. Z will gladly change her mind if we canproduce the essential truth with which w is inconsistent,or at least make it plausible that there must be some suchtruth. It’s just that as things stand she finds thisprospect highly unlikely. It’s as if someone were to say:“Even though it seems to you that there could be a purplespotted duck, the existence of such a thing is incompatiblewith the (unknown) essential truths.” Our ignorance ofessences is profound, as Z knows, so it’s always possible thatsome unknown essence rules out w and other worlds at whichthe moral principles are different. It’s just that asthings stand we have no reason to take this possibilityseriously, or so says Z.

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3. An argument against supervenience

We can turn these rough considerations into an argumentagainst strong supervenience. The first premise is theessentialist account of metaphysical modality due inrelevant form to Fine (1994a). The account starts with thepremodal notion of essence. Given any item x — object,property, relation, etc. — we have the truths that obtain invirtue of x’s nature or identity. It lies in the nature ofthe number 2, let’s suppose, to be a number, to follow 1,and so on. And so we have, in Fine’s 1995 notation:

2 2 is a number2 2 follows 1

By contrast, even though it is a necessary truth that thenumber 2 is not the moon, it does not lie in the nature ofthe number 2, considered by itself, to be distinct from themoon. Intuitively, one might know everything there is toknow about the identity of this number — about what makes 2the number that it is — without knowing the first thingabout astronomy. Consider, by contrast, the set {2, themoon}. It presumably lies in the nature of this set, notjust that the moon and the number 2 are its only members,but also that it is a two-membered set. To know the natureof a set is to know (inter alia) its cardinality. And so wehave:

{2, the moon} 2 ≠ the moon,

but not:

2 2 ≠ the moon.

Just as we can speak of the essences of individualitems, we can speak about the essences of pluralities orcollections (which need not in general be construed assets). If you and I are both essentially human, then,

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while it does not lie in your nature to be my species-mate(since your essence makes no reference to me), nor viceversa, it does lie in our essence, taken collectively, thatyou and I are members of a single species.

you, me There is a species to which you and I bothbelong (if we exist).

If there exist one or more items X such that it lies in thenature of the Xs that p, we say that p is an essential truth.8 8 Here I flag a subtle question about how to understand these plural or collective essences, viz., whether plural essences are separable:

Separability: a, b, … p, iff there are propositions A, B, … such that

aA, bB, … and A, B, … logically entailp.

The examples that motivate appeal to plural essences are generally consistent with this principle, and it simplifies the theory significantly to assume it, so I shall. The mainexamples that pull against separability concern non-identities. If a and b are distinct, they are necessarily distinct. If every necessary truth must be a logical consequence of essential truths, as Fine maintains (see immediately below), the we need to find some items X such that X a ≠b. When the essences of a and b are logically incompatible, a and b together will do the trick. (If it lies in the nature of Socrates to be an animal and in the nature of Mt. Rushmore to be inanimate, then these natures taken together will entail that Socrates ≠ Mt Rushmore, and so ground the necessity of their non-identity. But if a andb are two electrons, say, whose natures are logically compatible and perhaps even identical, their natures will not entail their distinctness as a matter of standard logic.We could invoke the set {a, b}, whose nature presumably doesentail that a ≠ b. But it sounds quite wrong to say that a

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We might argue about whether this notion is clearenough for serious use, but I’m going to suppose that it is.Even though it is officially primitive, it can be explainedat by means of examples, verbal glosses, by a formal theory(Fine 1995, 2000), and ultimately by the uses to which itmay be put elsewhere in philosophy.

With this notion in hand, Fine defines of metaphysicalnecessity as follows:

The essentialist account of metaphysical necessity.For a proposition p to be metaphysically necessary iffor there to be some collection of items X such thatXp

For a proposition to be metaphysically necessary just is forit to be an essential truth (or a logical consequence ofessential truths if essential truths are not automaticallyclosed under logical consequence, as I shall suppose theyare.) A proposition is metaphysically possible when it islogically consistent with the essential truths, orequivalently, when no collection of essential truthsconstitutes a (logical) obstacle to its truth. (For arelated view, see Peacocke 1999, ch. 4.)

Recall the world w*, which contains both the completedescription of a hydrogen atom H at the level offundamental physics and the proposition that H is a lithiumatom. This world is logically inconsistent with anessential truth, viz., the proposition that lithium atomshave three protons. According to the essentialist, that iswhy things could not have been as w* says they are. Thefriend of supervenience says that D(A) + AU is likewiseimpossible. So given the essentialist framework, the

and b are necessarily distinct because {a, b} essentially hastwo members. (That sounds backwards.) We cannot resolve this issue here, and I shall assume separability in what follows. (The alternative seems to me to involve a mysticalholism in the theory of essence.) If separability is false,the argument of this section does not go through.

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challenge is to identify the items whose natures rule itout.

The culprits cannot lie exclusively among the whollynon-normative properties and relations in D(A). Sayeverything there is to say about what it is for a thing tobe a proton or an elephant or a toothache: if thesecategories are genuinely non-normative, you will never findyourself mentioning moral permissibility or anything of thesort.9 The essences of these items are silent about moralpermissibility, and this ensures that these essences are allconsistent with D(A) + AU.

This is not a conjecture. We have not said how theline between the wholly non-normative and the rest is to bedrawn, but one clear constraint on the enterprise is this.If the essence of some item non-trivially involves aparadigmatically normative property like moralpermissibility, then that item must itself be reckonednormative. Since D(A) is, by stipulation, a wholly non-normative account of A, it follows that a completeelaboration of the essences of the items that figure in itwill not mention moral permissibility (except trivially),and will thus place no constraints on its extension. Theseessences cannot be obstacles to the truth of D(A) + AU.

If D(A) + AU is impossible, it must be inconsistentwith the essence of moral permissibility. (The culpritmight be some other normative item that does not figureexplicitly in AU, but we are pretending for now that9 Except perhaps in a trivial way. If essences are closed under logical consequence, as I assume they are, then it maylie in the nature of elephant that everything an elephant does is either permissible or not permissible. But that willonly be because for any property F, it lies in the nature ofelephant that every elephantine act is either F or not-F. Following Fine (1995), say that F occurs non-trivially in X’s essence iff X

(… F …), but it’s not the case that for all G, X (…G…). Then the claim in the text is the claim that normative items do not occur non-trivially in the essences of wholly non-normative items.

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permissibility is the only normative property on the scene.)And of course this is exactly what one sort of ethicalnaturalist maintains.

To a good first approximation, ethical naturalism isthe thesis that every normative item (property, relation,etc.) admits of real definition in wholly non-normativeterms. I emphasize real definition to make the familiarpoint that naturalism is not, in the first instance, athesis about moral language or moral thought. Present-daynaturalists mostly concede the Hume/Moore point that no non-normative predicate can have the same linguistic meaning orcognitive significance as a normative predicate, whilemaintaining that every moral predicate “picks out a naturalproperty”. But a natural property is a property that can bedefined in wholly non-normative terms.10 So thatnaturalist’s distinctive claim (again, to a firstapproximation) must be this: For each normative propertyM, there is a correct account of the form:

For a thing to be M just is for it to be ,

Or

Being M consists in (reduces to) being ,

where is a condition composed entirely of wholly non-normative ingredients.

This characterization may seem unnecessarilymetaphysical. But if this or something like it is not theview, then I don’t know what ethical naturalism is supposedto be. Ethical naturalism is not the view that the10 More exactly, a definable natural property is a property is a property that can be defined in wholly non-normative terms. Indefinable natural properties count as natural for some other reason. I suppose it could turn out that some normative property is also an indefinable natural property, inwhich case this characterization of ethical naturalism wouldneed revision. But this possibility is too far-fetched to bother with.

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normative supervenes on the natural. G. E. Moore and his21st century followers, including Parfit (2012) and Scanlon(2012), all accept supervenience, but they are not ethicalnaturalists just for that.11 The non-naturalist’sdistinctive claim is that even if there are truepropositions that specify naturalistic necessary andsufficient conditions for each moral feature — as there mustbe, given supervenience, if we allow infinitary conditions —these principles do not tell us what it is for an action tobe, say, right. They are rather metaphysically syntheticmoral laws that connect a normative feature, moralrightness, with utterly distinct non-normative features, theso-called “right-making” features. The naturalist’sdistinctive claim must therefore be that not only do suchprinciples exist: they tell us what it is for an action to beright.

For present purposes, a simple account of realdefinition will suffice. Say that defines F iff

(a) F x (Fx x)(b) The essences of the constituents of make no

non-trivial reference to F.12

On this account, ethical naturalism is the thesis that thenatures of the normative properties and relations, taken oneat a time, determine naturalistic necessary and sufficientconditions for their application. (A more relaxed form ofnaturalism would hold that the natures of the normativeproperties collectively determine such conditions.) Thealternative, ethical non-naturalism, is the view that in atleast one case, the essences of the normative propertiesfail to determine naturalistic necessary and sufficientconditions for their application. We may therefore statethe state the second premise in the argument againstsupervenience as follows:11 Moore’s position in Moore (1922) can be read, following Fine (2002), as rejecting the metaphysical supervenience of the ethical on the natural. 12 For a proposal that improves on this one, see Rosen (MS).

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Non-naturalism. There is a normative property M thatdoes not admit of real definition in wholly non-normative terms.

Given some simplifying assumptions, it can be shownthat these premises are incompatible with supervenience. Asis familiar, strong supervenience entails that each moralproperty is necessarily equivalent to some non-normativecondition. Take moral rightness as our example. Let a, b, …be all of the metaphysically possible right acts, and letDa(a), Db(b), … be their respective non-normativedescriptions. Strong supervenience then guarantees that

(2) x (x is right (Da(x) Db(x) …))

Given the essentialist account of metaphysical necessity,this is equivalent to

(3) Y Y x (x is right (Da(x) Db(x) …))

Now as we’ve seen, it can’t possibly lie in the natures ofthe non-normative properties, individually or collectively,that right should have some particular extension. (Theessences of the non-normative properties don’t mention right,except trivially, and so cannot constrain its extension.) Soif we assume, as we have thus far, that right is the onlynormative property on the scene, we can conclude that (3) istrue because (4) is true.

(4) right, P, Q, … x (x is right (Da(x) Db(x) …))

That is, the nature of right, possibly together with thenatures of various non-normative properties P, Q, …, entailsthat right is equivalent to the long disjunction on the righthand side.

Now if the list of additional properties P, Q, … isempty, (4) is a real definition of right in naturalisticterms and we’re done. We’ve derived ethical naturalism from

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supervenience in the essentialist framework. But of courseit is highly implausible that this list will be empty. Thevarious Dis are complete, fully detailed, non-normativedescriptions of acts. So they will mention things likequark color and black holes. But the nature of right hasnever heard of such things, or so it’s natural to suppose.(A definition of right that mentions quarks is like adefinition of house that mentions bricks: too specific to becorrect.) So the proponent of supervenience must thereforethink that it is the nature of right together with the natures ofvarious non-normative properties and relations that grounds theequivalence of right and the long non-normative disjunctivecondition.

We can complete the argument by invoking the principlecalled separability in note 8 above. This principle tells usthat when a truth is grounded in the essences of severalthings collectively, it is a logical consequence of theessences of those things taken individually. Given thisassumption, (4) entails that the equivalence of right and(Da(x) Db(x) …) must follow from two propositions, onegrounded in the nature of right alone, the other grounded inthe natures of various non-normative items: P, Q, etc. Butthat means that (4) must be a consequence of two principles:

(5a) right x (x is right x), and(5b) P, Q, … x (x (Da(x) Db(x) …)),

where is wholly non-normative. But then again, we’redone, since (5a) is a real definition of right in whollynon-normative terms. The argument shows that given oursimplifying assumption that right is the only normativeproperty on the scene, supervenience entails naturalism within theessentialist framework.

Things are less straightforward when we relax thissimplifying assumption. Suppose, for example, that thereare two normative properties, M and N, neither of which isdefinable in terms of the other. Supervenience entails theexistence of suitable biconditionals giving naturalisticnecessary and sufficient conditions for each.

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(6a) x (Mx x)(6b) x (Nx x)

Given the essentialist account, these in turn entail

(7a) M, X x (Mx x)(7b) N, Y x (Nx x)

where X and Y are lists of items whose natures play a rolein grounding the relevant equivalence. If X and Y areempty, or if they contain only non-normative ingredients,we’re done. These are, or can be shown to entail, realdefinitions of M and N in wholly non-normative terms. Thetrouble is that we cannot rule out the possibility that, forexample, the nature of N plays an ineliminable role ingrounding the equivalence of M and .

(8) M, N, X’ x (Mx x), but not: M, X’ x (Mx x).

Supervenience entails naturalism as we have defined it onlyif this cannot happen.

I note that this problem arises only if the natures ofM and N make no non-trivial reference to one another. Forif they do, we can invoke a principle in the logic ofessence, here called chaining, to rule out cases of the sortdescribed in (8).

Chaining: If xp and x figures non-trivially in y’sessence, then yp

The rationale for chaining is clear enough. Suppose it liesin the nature of knowledge that S knows that p only if Sbelieves that p, and that it lies in the nature of beliefthat beliefs have a certain functional role. Then itfollows intuitively that someone who knows everything there is toknow about what it is to know something must also know thatbeliefs have the functional role in question. If hedoesn’t, he hasn’t seen all the way to the bottom of the

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nature of knowledge. But that is just to say, reverting tothe metaphysical mode, that it must lie in the nature ofknowledge that beliefs have the functional role inquestion.13

If M’s nature makes non-trivial reference to N, itfollows from M, N x (Mx x) that Mx (Mx x), andhence that cases like (8) cannot arise.14 But suppose M’snature makes no reference to N. In that case I do not knowhow to derive a naturalistic real definition of M from the13 Fine (1994b) distinguishes several notions of essence. Chaining holds only for the notion there called mediate essence. But for independent reasons, that is exactly the right notion of essence for the account of real definition (Rosen MS). So it is not ad hoc in the present context to assume chaining. 14 Proof: Suppose

(1) M, N x (Mx x) and(2) N figures non-trivially in M’s essence.

It follows from (1), given separability, that

(3) There are propositions p and q such that: Mp, Nq, where {p, q} logically entails x (Mx x).

It follows from (2), given chaining, that:

(4) For any proposition q, Nq Mq.

From (3) and (4) we have:

(5) There are propositions p and q such that Mp, Mq, where {p, q,} entails x(Mx x)

Hence, given that essences are closed under logical consequence.

(6) M x (Mx x)

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assumption that the natures of M and N together determinenaturalistic necessary and sufficient conditions for M.15

The possibility strikes me as bizarre, and I can think of noremotely plausible cases that would illustrate it. But Icannot rule it out from first principles, and so cannot showthat supervenience entails ethical naturalism as we havedefined it.

And yet supevenience does entail a view that deservesto be called ethical naturalism, namely:

Ethical Naturalismalt: For each normative property Mthere is a non-normative condition such that M, N, …

x (Mx x), where M, N, … are all of the normativeproperties and relations taken together.

The naturalist’s key thought, it seems to me, is not thateach normative property is separately definable in non-

15 An artificial move might close the gap. Suppose M, N, …

x (Mx x). We can then ramsify, replacing the normative words in the formula with variables, and identify M as follows

M = the property X such that there are properties Y, etc., such that

X, Y, … x (Xx x).

This can then be converted in to what appears to be a naturalistic real definition of M in our format:

M x (Mx x possess the property X such that there are properties Y, etc., such that X, Y, … x (Xx x)).

This would be a non-standard real definition, in which the defined property is picked out, in the definiens, by means of a description that embeds the essentiality operator. Whether such definitions should be admitted is unclear.

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normative terms. It is rather that the normative facts arefixed by the wholly non-normative facts (e.g., facts ofphysics and psychology) together with the natures of thenormative properties and relations. On this sort of view,anyone who knows the non-normative facts is in a position toderive the ethical facts provided she also knows what it is foran act to be right, good, rational, etc. The non-naturalist’s distinctive commitment is that someone who knewthe natural facts and the essences might still be in thedark about the synthetic principles that connect thenormative facts to their non-normative grounds. Even ifsupervenience does not entail the separate definability ofthe normative properties, it does entail naturalism in thissomewhat more capacious sense.

And so we have a proof of ethical naturalism fromsupervenience and the essentialist account of metaphysicalmodality. Equivalently: We have a proof in theessentialist framework that if ethical non-naturalism istrue, strong supervenience is false.16

4. The status of the premises.

Of course what we really have is an inconsistent triad:

Strong SupervenienceThe essentialist account of metaphysical modalityEthical non-naturalism.

If any two are true, the third is false. I have called thisan argument against supervenience. But it has not escaped16 It is often said, following Blackburn (1993), that non-naturalists have trouble account for supervenience, and thatthis provides a powerful, though inconclusive, objection to the view. See (McPherson 2012) for a recent defense of this position. My claim is stronger: if the Finean essentialist is right about the nature of metaphysical possibility and necessity, then non-naturalists must reject supervenience. (As I will go on to show, this is a feature, not a bug.)

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my notice that others will see things differently. So letme be clear about the status of this argument as I see it.

In my view, the essentialist account of modality andethical non-naturalism are both (separately and together)serious contenders. Apart from Lewis’s modal realism, theessentialist account has no clear rival as a reductiveaccount of metaphysical necessity; and while I would notobject to taking the metaphysical modal notions as primitiveif there were no alternative, the essentialist accountpromises to ground and explain the facts of metaphysicalmodality in a compelling way. If nothing else, theessentialist account strikes me as a permissible sharpeningof the perhaps somewhat unclear notion of metaphysicalnecessity, and indeed as the most fruitful such sharpeningyet proposed.17

As for ethical non-naturalism, I claim only that in theabsence of credible reductive proposals or reasons to thinkthat some naturalistic reduction must be possible, thequestion whether the normative facts reduce to natural factsremains wide open. We simply do not have clear enough viewof the natures of the moral properties and relations to saywhether these natures determine naturalistic necessary andsufficient conditions for their application. We shouldtherefore be prepared for the possibility that some ethicalproperties are not reducible, and hence for the possibilitythat supervenience is false.

Fine himself takes a harder line, arguing on generalgrounds that ethical naturalism is clearly false (Fine 2002,§4; also Parfit 2011, v.2, §25). But it seems to me thatFine’s argument (by dilemma) misses a possibility.

Fine shows persuasively that if there is some essentialequivalence between a normative property like right and anatural property like being such as to maximize happiness, it isneither a conceptual equivalence nor an a posterioriequivalence of the sort favored by naturalist who take17 I argue for the unclarity of the received notion of metaphysical necessity, and for the availability of the essentialist sharpening, in (Rosen 2006). For an alternative sharpening, see (Kment 2014).

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reduction in the sciences as their model. But there is roomfor another view according to which truths of the form Mx(Mx x) are neither conceptual nor empirical, but ratherthe sort of truth one comes to know, if at all, throughphilosophical reflection. Suppose we sit down to noodle outthe single true morality, testing hypothesis against ourjudgments about cases and seeking equilibrium, and supposethat at the end of the day we find ourselves endorsing acounterfactual-supporting universally quantifiedbiconditional:

x (x is right x),

where is non-normative through and through. One sort oftheorist — Parfit certainly, Fine perhaps — will contemplatethis culmination of centuries of philosophy and say: “Thisprinciple is true; it may be necessary in a sense. But itdoesn’t say what it is for an action to be right. It is rathera synthetic moral law connecting two utterly differentaspects of reality.” But we can imagine another reaction:“I didn’t see this coming, but now that I see what the basicprinciple governing rightness is, I see that we now have thesort of understanding of rightness that mathematicians havelong had of notions like continuity, and to whichphilosophers aspire when they ask “What is F?” questions asthey have since Socrates. This knowledge is not analytic orconceptual in any useful sense, nor is it empirical. Butit’s not simply knowledge of a synthetic law. Ratherethical reflection has delivered an account of the nature ofmoral rightness cast entirely in naturalistic terms.” Canwe know in advance — without seeing — that it would bewrong to respond in this way?

Fine does not address the possibility, but his remarksagainst conceptual naturalism are apposite. Extracting thesound point in Moore’s Open Question Argument, Fine writes:

Perhaps a more satisfactory way to formulate theobjection is as follows. If there is a correctanalysis of good, say, as what promotes pleasure over

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pain, then something’s being good musty consist innothing more than its promoting pleasure over pain. Butwe have a strong intuition that it does consist insomething more. Here we are not relying on thepurported epistemic status of a correct analysis, as isMoore, but on its metaphysical consequences. (Fine2002, 270)

We can take this as a prediction that even if we werepresented with a compelling principle connecting good withsome non-normative condition, we would not respond in thesecond way canvassed above, treating the equivalence as realdefinition, but rather in the first, treating theequivalence as a synthetic law.18

For what it’s worth, my hunch is that Fine is rightabout this. But I don’t think we’re entitled to muchconfidence on the point, since we’ve seen very few seriouscandidate analyses. As an antidote to this intuition,consider Schroeder’s account of reasons for action(Schroeder 2007). Schroeder takes up the metaphysicalquestion: What is it for R to count as a reason for X to doA? The inquiry is thoroughly a priori. Putative accountsare tested against hypothetical cases and refined in thearmchair. The first upshot is a plausible counterfactual-supporting biconditional:

For all propositions R, agents X and actions A, R is areason for X to do A iff there is some proposition Psuch that X has a desire whose object is P and thetruth of R is part of what explains why doing Apromotes P. (Schroeder 2007, 57)

After defending the biconditional, which is meant to bewholly non-normative on the right, Schroeder makes thestronger claim that the account yields a real definition ofreason. Of course we can doubt the extensional correctness18 Fine’s claim is an expression of what Enoch calls the “just too different” intuition (2007:44, n. 47) See (McPherson 2012) for discussion.

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of the account, but suppose we don’t. Fine’s objection tonaturalism, applied to this case, would run as follows:

If this is a correct analysis, then something’s being areason for X to do A must consist in nothing more thanit’s explaining why A would promote the satisfaction ofone of X’s desires. But we have the strong intuitionthat it does consist in something more.

But do we have this intuition? I can’t say that I do. Moreexactly, I can’t tell whether I have the Finean intuition ofa metaphysical gap between the normative relation on theleft and the natural condition on the right, or instead theirrelevant Moorean intuition that the two formulae havedifferent meanings. If I thought that something like thiscould be done for every normative property and relation, Iwould be optimistic about the prospects for reductivenaturalism in ethics. As things stand, I’m pessimistic.But that’s just an expression of my state of mind. As amatter of philosophy, the question remains open.

So I do not say that naturalism is false, or that wehave strong grounds for rejecting it. I say only that wehave no strong ground for accepting it19, and that we shouldthus prepare for the possibility that naturalism is false.Put another way: we should not assume supervenience as apremise in metaethics, since it stands and falls withnaturalism, and naturalism is unsettled. The argument thusfar is meant to motivate this stance.

5. Normative Necessity and Fact-Independence

19 “But isn’t the plausibility of supervenience evidence for the truth of naturalism?” No, it is not. As I suggest below, once we distinguish standard supervenience theses from weaker versions, we will see that the plausible thesis in the vicinity, and the thesis that moral theory and practice tacitly take for granted, is not strong supervenience, but aweaker claim that is consistent with non-naturalism.

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Suppose the oracle of philosophy tells us that Fine isright: right about metaphysical modality, and right inthinking that at least one normative property cannot bedefined in non-normative terms; hence right in rejectingsupervenience. This means that some true conditionals ofthe form

x (D(x) N(x))

are contingent truths, where D(x) is the complete non-normative profile of some act, and N(x) is its normativeprofile. Still, as Fine notes, we are powerfully inclinedto think that given that an act has certain non-normativefeatures, it has to be (say) wrong. It is no accident that itwas wrong for me to bribe the judge, given that my act hadthe natural features that it had. Any act with thosefeatures would have been — would have had to be — wrong.But that is just to say that even if the relevantconditional is not metaphysically necessary, it is not anaccidental generalization either. In this respect itresembles a law of nature: necessary in a sense, but notabsolutely necessary.

The same goes for the general moral principles thatmoral philosophers typically seek: exceptionless laws thatspecify the conditions under which it is permissible tobreak a promise or cause harm or do anything at all. Suchprinciples are elusive. But everyone agrees that if wefound them they would not be true only because every actualact of promise breaking in such and such circumstanceshappens to be permissible. They would supportcounterfactuals. If it’s a true moral principle that it’s okto break a promise in conditions C, it follows that if Bobhad broken a promise in C, his act would have been ok.

Fine says that principles of this sort — the detailedfact-norm conditionals and general moral principles if theyexist — possess a sui generis species of necessity: they arenormatively necessary. The true supervenience claim is not thestandard one, formulated in terms of metaphysical necessity,but rather the weaker claim that the natural facts determine

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the normative facts as a matter of normative necessity (Fine2002). That is: For each fully determinate constellation ofnon-normative facts D, there is a constellation ofnormative facts N, such that as a matter of normativenecessity, if D obtains then N obtains. Fine argues thatnormative necessity cannot be defined in terms ofmetaphysical necessity (or natural necessity) and leaves itopen whether more can be said about its nature.

I believe that more can be said. Start by focusing onthe complete fact-norm material conditionals of the form D N, where D is a complete and consistent specification of away for the non-normative world to be, and N a completeassignment of normative properties and relations to theitems that would exist if D were actual. Some of theseconditionals are false. Throw those out. Some are true,but only because the antecedent is false. More exactly, someare such that the counterfactual, “If D had been the case,then N would have been the case” is false. Throw those outas well. What remains are the true fact-norm conditionalsthat would still have been true if their antecedents hadbeen true, or in other words: the fact-norm conditionalsthat would have been true no matter how the non-normative facts hadbeen.

These are precisely the fact-norm conditionals that weare inclined to regard as necessary — as metaphysicallynecessary if we are incautious, as normatively necessary ifwe’ve seen the light. Let D specify in complete detail thenatural features of a world rather like this one in whichFred tortures a cat for kicks. There are countless trueconditionals of the form D N, where N is a completespecification of the normative facts. But we are powerfullyinclined to think that for each complete specification ofthe non-normative facts D, there is only one truecounterfactual of the form, “If D had been the case then Nwould have been the case,” and that the consequent of thisconditional tells us not only how things would have been hadD been true, but how things would have to have been in such acase. This counterfactual-supporting fact-norm conditional

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is normatively necessary. The rest are at best accidentallytrue.

We can generalize the point. Say that p is fact-independent if p is the case and would have been the case nomatter how things had been in wholly non-normativerespects.20 Fact-independence is clearly an importantfeature. If a proposition is fact-independent, it wouldstill have been true no matter what we had done, no matter how hardwe had worked to falsify it, no matter how history had transpired, no matter howthe initial conditions of the physical universe had been configured, no matterwhat the laws of nature had been, and so on. Moreover, these areall marks of necessity. They are features of the essentialtruths,21 the logical and the pure mathematical truths, atleast as we normally conceive them. All of which suggests aproposal: for a proposition to be normatively necessary justis for it to be fact-independent.22

Normative necessity defined. For a proposition p to benormatively necessary at w is for p to be aproposition true at w such that for any wholly non-normative proposition q, the counterfactual “if q hadbeen the case, p would still have been the case” istrue at w.23

20 Again, since I assume that normative claims are fully factual, this is terminology is shorthand. “Fact independence” is really “wholly-non-normative-fact-independence”. 21 Pace Salmon (1989), who argues that ordinary material objects would have had different essences if they had been made from slightly different matter. For discussion see (Leslie 2011). 22 There is room for a slightly weaker proposal, viz., that the normative necessity of p is always grounded in, or explained by, the fact that p is fact-independent. Nothing inwhat follows will turn on the distinction between this view and the view defended in the text, viz., that normative necessity just is fact-independence.

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6. Normative necessity (i.e., fact-independence) is theonly necessity that ethics needs

The idea that moral principles are normativelynecessary in this sense jibes well with the case-basedmethodology of moral theory. Suppose we’re studyingpromissory morality and want to know, for example, when it’smorally permissible to break a promise. On the table is aprinciple that says:

It’s permissible to break a promise if C.

According to the usual case-based methodology, we test suchprinciples by entertaining hypothetical cases in which C23 Given the conventional assumption hat counterfactuals with metaphysically impossible antecedents are vacuously true, this entails that metaphysically necessary truths are all normatively necessity, and is thus compatible with a picture according to which the sphere of normatively possible worlds is nested strictly within the sphere of metaphysically possible worlds. If we relax this assumption, as is sometimes convenient (Nolan 1997), then some metaphysically necessary truths will be normatively contingent. For example, the proposition that 2+2=4 may be metaphysically necessary, but it will fail the test for normative necessity, since it would have been false if (per impossibile) there had been no numbers.

This yields a two-way dissociation of metaphysical possibility and normative possibility. There are metaphysically impossible worlds that are normatively possible — worlds at which the normative principles are justas they are but (say) numbers don’t exist. But there are also metaphysically possible worlds that are normatively impossible: worlds at which act utilitarianism is true, for example. This in turn entails that the class of normativelypossible worlds and the class of metaphysically possible worlds cannot both be spheres around the actual world in the sense of Lewis 2001.

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holds and then asking whether it would be permissible tobreak a promise in such a case. (Note the counterfactual inthis formulation.) If we find a case of this relevant sortin which breach of promise would be wrong, then as wenormally think, we’ve got a counterexample that sinks theprinciple. But suppose a proponent of the principle hearsthe case and shrugs: “Oh, I agree that the principle wouldhave been false if the facts had been as described; but thatdoesn’t mean it is false, since the facts are not asdescribed”. This response is confused, and it’s easy to saywhy. The principle was proposed, after all, as a putativemoral principle. Even if it sounded like an unadornedmaterial conditional, something stronger was intended, viz.:

As a matter of (some sort of) necessity: It’spermissible to break a promise if C.

Any moral principle worth the name must apply, not just inthe actual world, but across a range of possible worlds. Andso we face the question: What sort of necessity must attachto moral principles if our case-based methodology is to makesense? And I claim: Normative necessity as we have definedit would do quite nicely.

Of course in some parts of ethics we’re content withprinciples that would have been false if the facts had beendifferent in certain ways. In medical ethics, we can’trefute a candidate principle governing the allocation ofkidneys by pointing out that it would have been false ifkidneys had grown on trees. But there is a part of moraltheory — pure moral theory —in which purported principlesare vulnerable even to the most far out counterexamples. Inthis part of ethics, if a putative principle would be falseif death were temporary (like sleep), or if people spawnedlike salmon, then that principle is false as stated. Unlikethe empirically grounded precepts of applied ethics, theprinciples of pure moral theory are supposed hold, as itwere, on moral grounds alone. The case-based methodology ofnormative ethics seeks to identify these principles roughlyas follows: We consider hypothetical cases and ask whether

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some putative principle would have been false if the factshad been as specified. If so, we have a counterexample andthe principle takes a hit. If we look hard forcounterexamples and fail to find them, the principle is tosome degree confirmed. All of this makes perfect sense if the aim of puremoral theory is to identify principles that hold of normative necessity as we havedefined it. When all goes well our methodology works to screenout principles that would have been false had the facts beendifferent, and so to certify principles that would have beentrue no matter how the facts had been.

But note: As we ordinarily think, it is no objectionto a putative principle of promissory morality, say, that itwould have been false if act utilitarianism had been true. Perhapsthis is because we take it for granted that actutilitarianism could not possibly have been true, and moregenerally, that pure moral principles are metaphysicallynon-contingent. However, no such assumption is needed to make sense ofour practice. For that purpose it is enough to suppose that weexpect pure moral principles to exhibit fact-independence.Philosophers who self-consciously accepted the metaethicalview I have been discussing and who sought pure moralprinciples that were normatively necessary butmetaphysically contingent would conduct their first orderinquiry in moral theory just as we actually do. Nothing inthe practice of moral theory assumes or presupposes that thepure moral principles we seek hold of absolute necessity.

The proposal also makes sense of the role of moralprinciples in ground level moral practice. When aconscientious person makes a moral judgment about a case,she brings her (often tacit) knowledge of principles tobear. Inevitably this involves the assessment of unchosenoptions — options that have not been taken or will not betaken. The conscientious decision-maker needs to know inadvance which of her options is permissible; but moreexactly, she needs to know which of her options would bepermissible if she took it. The conscientious moral judge needs toknow whether things would have been better or worse had theagent acted differently, etc. For all of these purposes we needmodally robust moral principles: principles that are true

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and would still have been true had the agent acteddifferently. Normatively necessary principles would suffice,since their fact-independence guarantees that they wouldstill have been in place no matter what anyone had done.And yet it is quite irrelevant for these purposes if suchactions are permissible in remote possible worlds where the moral lawsare different. Even if there are worlds of this sort, ourpractices of choice and assessment never lead us to considerthem.24 When we rely on moral principles in practice weassume that they are robust enough to be held fixed inreasoning about how things would have been had the non-normative facts been otherwise. But we do not assume, andneed not assume, that our principles could not have beenfalse under any circumstances. Moral practice simply takesno stand on whether counter-moral worlds are possible. Ifwe have determined that act utilitarianism is false, andthat it would not have been true no matter how the facts hadbeen, it simply does not matter for practical purposeswhether remote worlds in which it is true get classified as“possible” in some other sense.

This last point amounts to the claim that nothing inmoral practice assumes or presupposes Strong Supervenience.I do not claim to have established it. But I honestly can’tthink of anything in our use of moral principles that caresabout whether remote scenarios that would supplycounterexamples to supervenience get classified asmetaphysically possible or impossible. The scenarios are“coherent”, and so we can entertain them if we like, nomatter how we classify them. We take it for granted that theactual moral principles, whatever they may be, would stillhave been in place no matter what we had done, no matter howthings had gone, and so on, and hence that supervenienceholds within the sphere of worlds that we can arrive at bystarting with the actual world and varying the non-normativefacts by counterfactual supposition. If we assume something24 Unless, of course, we are uncertain about the moral principles, in which case deliberation and assessment may lead us to consider words which are, in fact, worlds whose moral principles differ from the actual moral principles.

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stronger, I can find no trace of that assumption in the usesto which moral principles are put.

These remarks are meant to suggest that themetaphysical view I have been discussing is non-revisionarywith respect to moral theory and practice. If this isright, then received ideas like supervenience and non-contingency cannot derive authority from these sources.

6. The Explanatory Structure of Normative Reality

This account of the modal status of moral principlessuggests a picture of normative reality that we should makeexplicit. According this picture, every world includes aclass of fact-independent normative propositions.25 Theseare the normative laws of w, the propositions that hold atw as a matter of normative necessity. In general, theseprinciples are metaphysically contingent: they do not holdin virtue of the natures of their constituents, so there aremetaphysically possible worlds in which they vary. But theyare necessary in the sense that they are not contingent onwhat happens.

The domain of pure moral principles is heterogeneous.It includes fully detailed counterfactual-supporting fact-norm conditionals D N, where D gives a fully detailedspecification of a way for the non-normative facts to be.But it also includes principles that look more like general,action-guiding moral precepts — principles that apply acrossa range of cases. These pure principles, moreover, are notall on a par. Some ground others, and are in that sense morefundamental.26 For one sort of particularist, the25 The class can be empty, to allow for worlds relative to which normative properties and relations are altogether alien.26 According to me, the grounding relation among normative principles is the same metaphysical grounding relation that holds in other areas (Rosen 2010). In a slightly different context, Fine (2012) posits a distinct grounding relation that holds between the natural features of an act and its normative features. I say instead that in such cases, the

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explanatorily basic principles are the detailed fact-normconditionals in all of their infinite complexity andmultiplicity; principles of general applicability hold onlybecause these more determinate principles are as they are.The more conventional moral philosopher, by contrast, holdsout for a small number of fundamental general principlesthat underlie the detailed fact-norm conditionals and anynumber of mid-level principles. He may even hold out for asingle fundamental law — the “supreme principle ofmorality”— that grounds every other normative principle. Nomatter how this issue is resolved — and it may be resolveddifferently in different worlds — the pure moral principlesare all normatively necessary, even though some are to beexplained in terms of others, just as the truths ofmathematics are all metaphysically necessary, even thoughsome are to be explained in terms of others.

Suppose there is a single pure moral principle thatexplains the rest. We can then field the question: Why isthis the supreme principle of morality when it might just aswell have been… Act Utilitarianism? It is a feature of theframework we have assumed that this question can have noanswer. The supreme principle can’t be explained byreference to deeper principles, since by hypothesis thereare none; and it can’t be explained by reference tocontingent natural facts, since it would have been just asit is no matter how those facts had been. If ethicalnaturalism is true, it will be grounded in the natures ofthe properties and relations that figure in it, and pointingthis out would yield a maximally satisfying answer to ourquestion.27 But if ethical naturalism is false, then the

normative features of the act are grounded in its natural features together with a bridge law that holds of normative necessity. 27 The explanation would be of the form: p because it lies in the nature of (say) moral permissibility that p, by analogy with: water is H2Obecause water is essentially H2O. Some people deny the explanatory force of these remarks and hear them instead as rejections of the demand for explanation. Either way, ethical naturalism would ensure that our question — Why is the

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supreme principle of morality can only be a brute,inexplicable metaphysical contingency. If there are manysuch basic principles, the ethical facts will ground out ina plurality of brute contingencies.28

This is a consequence of the picture of moral realitywe have been discussing, not an objection to it. There is nodenying that ethical naturalism would be a more satisfyingpackage in this respect. When a series of why-questionsterminates in an answer of the form “p because it lies in the natureof x that p”, the question is well and truly answered and thereis no residual mystery. If ethical naturalism is false,however, it simply follows that some basic normativeprinciples are inexplicable.29 In this respect they wouldresemble the fundamental laws of nature as pictured by non-Humean views on which the laws are grounded, neither in themosaic of particular fact nor in the essences of theproperties that figure in them. Such views may beobjectionable, but not because they posit laws that cannotbe explained. There is no reason whatsoever to expect, or toinsist, that every law or principle must be explicable.

It cannot be stressed enough that this commitment toinexplicable moral principles is a feature of any non-naturalist view, not just mine. The conventional non-naturalist who embraces Supervenience and Non-Contingency(and so rejects the essentialist account of metaphysicalmodality) must agree that basic moral principles are

supreme principle of morality as it is? — gets an answer if it needs one.

28 For a discussion of brute contingencies in another context, see (Wright and Hale 1992, 1994) and (Field 1993). 29 I have ignored the remote possibility that there might beinfinite descending grounding chains in ethics, where principle P is explained by Q, which is explained by R, etc., ad infinitum. To my knowledge, no one has ever seriously suggested that ethics might have this structure, but it would good to know whether this is a genuine (metaphysical) possibility.

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inexplicable. Of course she will add that these principlesare metaphysically necessary truths. But if challenged toexplain why these basic principles include p but not q, shewill fall silent. It is sometimes said that the demand forexplanation arises only for contingent truths, and hencethat conventional non-naturalist can legitimately shrug itoff in a way that my sort of non-naturalist cannot. Butthis is just not so. There are genuine explanations inmathematics and metaphysics. We give them all the time.Even in ethics the conventional non-naturalist is presumablyhappy to entertain explanations of more specific moralprinciples in terms of more general ones. So even she willhave to acknowledge that on her view, some truths of a sort thatsometimes admit of explanation cannot be explained. This is justa fact of life for the non-naturalist, and no one should beembarrassed by it.

7. Explaining the normative necessity of moral principles

Given a fact-independent moral principle p, it is onething to ask, “Why is p the case?” and another to ask, “Whyis p fact-independent?” Questions of the first sort do notalways have answers, as we’ve just seen. But questions ofthe second sort can always be answered, and seeing this willprovide a clearer view of the metaethical picture I’ve beendiscussing.30

To say that p is fact-independent is to say that for anywholly non-normative proposition q, if q had been the case,p would still have been the case. Given the standard30 This question is analogous to a familiar question in the philosophy of science: “Given that L is true, why is L a law? Why does this fact exhibit this particular species of necessity?” The corresponding question is rarely asked in ethics, presumably because we’ve been hazy about the distinctive species of necessity that distinguishes pure moral principles from mere moral facts. Now that we have aclearer view of this distinctive species of necessity, the question is ripe for asking.

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account of counterfactuals, this amounts to saying that forany non-normative proposition q, the q-worlds most similarto the actual world are always p-worlds. So we canreformulate our question as follows: Give some pure moralprinciple p, why are the nearest worlds in which the facts aredifferent always worlds in which p remains in place?

To see the point of the reformulation, consider aschematic case. Here you are in the actual world, with non-normative description D and moral principles M,contemplating some action A. The actual moral principlesprohibit A, and since you’re a good egg, you don’t do it.But if you had, the non-normative facts would have beendifferent in various ways. Suppose for simplicity thatthere is a single determinate way these facts would havebeen had you done A. Call it D*. Now there are D*-worldsin which the actual moral principles M are all in place,and in those worlds you act wrongly by doing A. But thereare also D*-worlds in which those principles are differentand your act is right. To say that the actual moralprinciples are fact-independent is just to say that D*-worlds of the first sort are always more similar toactuality than D*-worlds of the second sort; or in otherwords, that whenever we have three worlds:

@: D, M

w1: D*, M

w2: D*, M*

w1 is more similar to @ than w2 is. The challenge is toexplain why this is so.

This may seem trivial. After all, w1 and w2 are exactlyalike in non-normative respects, so they are equally similarto @ along that dimension. But w1 also resembles @ in itsbasic moral principles, whereas w2 departs gratuitously from@ in this respect. So isn’t it automatic that w1 is morelike @ than w2 is?

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No, this is not automatic. For all we’ve said, theremay be respects in which w2 matches @ but w1 does not. Thesepoints of similarity will not be wholly non-normative, andthey will not concern pure moral principles. Rather theywill concern mixed normative facts. Here’s an example.

Suppose that in the actual world @ with non-normativedescription D and moral principles M, you perform cosmeticsurgery on Sam with his consent, turning the frog into aprince. This act A is permissible, let’s suppose. (You’re acredentialed plastic surgeon.) So M and D together entailthat A is permissible. Now ask how things would have beenif you had performed the surgery without Sam’s consent. Supposeagain, just for simplicity, that there us a single way thefacts would have been if you had done this, D*. There is aD*-world — call it w1— in which the actual moral principlesM are still in place, and we confident that in w1 your actis wrong. But there is also a D*-world, w2, in which actutilitarianism is true. And it may well be that in thatworld A is permissible (because the world is happier overallwith Sam’s appearance improved, his lack of consent tosurgery notwithstanding). Now we are confident that if youhad not secured consent, it would have been wrong to performthe surgery, or in other words, that w1 resembles @ moreclosely than w2 does. But it is not immediately obvious whythis should be so. The two worlds are exactly alike in non-normative respects. w1 agrees with @ about the pure moralprinciples M, but disagrees with @ about the permissibilityof A; while w2 agrees about the permissibility of A (andabout many other particular moral facts), but disagreesabout the moral principles M. So if we are simply countingpoints of similarity and difference, neither world isclearly closer than the other. And yet it seems quite clearthat similarity with respect to moral principles counts forquite a lot, whereas similarity with respect to particularmoral facts counts for very little in this case. To explainwhy the moral principles in M are fact-independent is toexplain why this is so.

The idea we need comes from recent papers by BorisKment and Ryan Wasserman (Kment 2006, Wasserman 2006).

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Recall Fine’s famous “future similarity” objection toLewis’s theory of counterfactuals (Lewis 2001, Fine 1975).Nixon did not press the button in 1969, but if he had therewould have been a nuclear conflagration. In the Lewisianframework, this amounts to the claim the possible worldsmost similar to the actual world in which Nixon pushes thebutton are worlds in which the missiles fly and the post-1969 future is radically different from the actual post-1969future. But of course there are worlds in which Nixonpushes the button and the signal dies in the wire, and insome of those worlds the future plays out almost exactly asit actually did. These latter worlds are intuitively muchmore similar to the actual world than any world in which thehuman race is wiped out by a nuclear holocaust in 1969. Sowhy don’t we accept the counterfactual, “If Nixon hadpressed the button, the signal would have died in the wire”?Lewis’s response is that the theory of counterfactualsrequires a standard of comparative similarity that isotherwise unfamiliar, one according to which near perfectconformity to the laws of nature matters a great deal,whereas approximate match of particular fact matters not atall (Lewis 1979). Lewis’s account can be rigged to givethe right answers in an impressive range of cases, and itcould be extended to cover our case by stipulating thatmatch of moral laws counts more than match of particularmoral fact. But crucially, Lewis does not explain why somerespects of similarity matter more than others, and in theabsence of such an account, this sort of ad hoc extension ofthe theory would be unilluminating.

Kment and Wasserman provide a compelling principle atjust this point. Let w* be a nearby world in which Nixonpushes the button and the signal dies in the wire. w* hasmuch in common with the actual world. In both, forinstance, you are reading this paper now. But note:Although the worlds have this fact in common, the explanationof this fact is different in the two worlds. In the actualworld, the fact that you are reading this paper now hasnothing to do with a fluky electronic glitch in Nixon’sbomb-launching apparatus, while in w* this glitch plays a

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crucial role in explaining this fact. Kment and Wassermantake this to be the telling point. As Kment puts theprinciple:

(C) If some fact f obtains in both of two worlds, thenthis similarity contributes to the closenessbetween the two worlds if and only if f has thesame explanation in the two worlds. (Kment 2006:282)

The future similarities between w* and actuality do notsatisfy this condition, so they do not count. That is whythe most similar world in which Nixon presses the button isnot w*, despite these future similarities, but rather aworld in which the missiles fly.31

With this in mind, return to Sam’s cosmetic surgery.We have three relevant worlds:

Non-normativefacts

Pureprinciples

Particularnormativefacts

@ D M A ispermissible

w1 D* M A is notpermissible

w2 D* AU A ispermissible

31 Of course (C) by itself does not explain why worlds in which the missiles fly are closer. For that we need other principles that tell us how the similarities that do matter are to be weighted. See (Kment 2014, ch. 11) for a derivation of those principles.

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We want to know why w1 is more similar to @ than is w2, andthe Kment/Wasserman theory tells us why. @ and w1 agreeabout pure moral principles. This similarity counts becausethese principles have the same explanation in both worlds.The basic principles are not explained at all, and thederivative pure principles are grounded in the basicprinciples in the same way in both worlds. By contrast,even though @ and w2 agree about the permissibility of thesurgery, the explanation for this particular fact is verydifferent in the two worlds. In @ it is explained by thefact that Sam consented to the surgery together withpertinent moral principles in M. In w* it is explained bythe good consequences of the surgery together with theprinciple of utility. Since the facts have differentexplanations, this point of similarity counts for nothing.

These considerations can be generalized to show thatthe nearest world at which the natural facts are differentin some specified way is always a world that resembles theactual world in respect of pure normative principles. Theargument depends on a substantive assumption about thestructure of the normative domain, viz., that all normativefacts are ultimately grounded in pure normative principlestogether with non-normative facts.32 Given thisassumption, we can explain why pure normative principles arefact-independent, hence normatively necessary, by pointingto the deeper fact that pure normative principles areexplanatorily independent of the natural facts. In fact itwould be best to say that this is what renders the pureprinciples pure. It is then a substantive thesis that the32 This is highly plausible, but substantive. It would be false if it were possible for an individual act to be (say) wrong, not because it had some feature (qualitative or otherwise) that combines with a pure principle to ground itswrongness, but rather brutely. It is very hard to believe that this is possible. It seems to me to lie in the nature of normative properties and relations that facts of the forma is N, for normative N, are always grounded in non-normative features together with general principles. If that is not so, the argument of this section will need rethinking.

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pure moral principles are counterfactually independent ofthe non-normative facts. The Kment/Wasserman idea then helpsus to explain this substantive fact, and so to explain whythe pure normative principles are, if not absolutelynecessary, nonetheless necessary in a sense.

8. Recapitulation

In the first part of the paper I argued that for all weknow, the pure principles of morality are not metaphysicallynecessary. They would be metaphysically necessary if, butonly if, the natures of the various normative properties andrelations determined naturalistic necessary and sufficientconditions for their instantiation, and we simply do notknow enough about these natures to know that this is so. Weshould therefore be prepared for the possibility that somepure normative principles are contingent, and hence for thepossibility that the normative fails to supervene on thenatural.

It is nonetheless a datum that normative principles arenecessary in a sense. It is no accident — no merecontingent truth — that an act with the natural features ofthe act you are performing now is a permissible act. Fineclaims that these principles are necessary in a sui generissense, and we have been exploring that possibility. I havesuggested that the normative necessity of moral principlesconsists in their fact-independence. The pure normativeprinciples of are true and would still have been true nomatter how the non-normative facts had been. A fortiori,they would still have been in place no matter what we haddone or thought, no matter how society had been organized,and so on. That is a kind of necessity and (I claim) theonly necessity that ethics needs.

The challenge then was to explain why pure normativeprinciples are necessary in this sense. The proposedexplanation turns on the fact that pure moral principles areexplanatorily independent of the natural facts. (We tookthis as a definition of purity.) Given this assumption, theKment/Wasserman point about counterfactuals entails that the

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nearest worlds in which the natural facts are different areworlds in which the pure moral principles are as they are.We have thus derived the fact-independence of pure moralprinciples from their purity, and so explained why suchprinciples are necessary in their distinctive way.

With this in mind, return to the question with which webegan. If you are like most philosophers you used to find itperfectly obvious that the normative strongly supervenes onthe natural — so obvious that no argument for this slightlyarcane thesis seemed necessary. If the account I havesketched is cogent, you can now entertain an alternative tostrong supervenience: the view that the normative superveneson the natural as a matter of normative necessity. (Thisfollows from the normative necessity of pure moralprinciples, together with the further assumption that allnormative facts are ultimately grounded in pure principlesplus non-normative facts.) These views disagree about themodal classification of remote worlds — worlds in which actutilitarianism is true and the natural facts are just asthey are, for example. Everyone agrees that such worlds areimpossible in a sense. The open question concerns theinterpretation of the modal word in this formulation.Having seen the alternative, are you confident that theseremote worlds must be metaphysically impossible — ruled out bythe natures of the moral properties and relations? If so, youseem more deeply into these natures than I do.

9. Challenges

Needless to say, the metaethical picture I have beenpainting raises questions. If one grants that the puremoral principles are metaphysically contingent, one mightwant to know, for example, how much variation is(metaphysically) possible. Suppose we have a possible worldlike our world, in which act utilitarianism is false, and aworld like w in which the non-normative facts are just asthey are but act utilitarianism is true. Does it follow— as it might, given a familiar principle of recombination —that there is a possible world with the same natural facts

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in which act utilitarianism is true until December 31, 1999and false thereafter? Are there worlds that falsify weaksupervenience — worlds in which non-normative duplicates differin some normative respect?33 Are there possible worlds justlike our world in non-normative respects in which the onlyimpermissible act is the act you are performing now? Arethere metaphysically worlds in which Caligula’s moralprinciples are true?

The short answer is: no one knows. These bizarreworlds are impossible iff they are ruled out by the essencesof normative properties and relations, and our insight intothese essences is sadly limited. That said, it is consistentwith my view that these normative features have essencesthat impose stringent constraints on which propositionsinvolving them are possible. It presumably lies in thenature of permissibility that permissibility is a propertyof actions. That rules out worlds in which the sun ismorally permissible. A more interesting possibility is thatlies in the nature of the normative properties and relationsthat particular facts involving them are always grounded ingeneral principles. The idea would be that for each (basic)normative feature N it lies in the nature of N that if x isN, x is N in virtue of fact that x is D (where D is whollynon-normative), together with the fact that for all x,whatever is D is N. If we add that these generalprinciples must be qualitative, not mentioning particularindividuals, places and times, that would rule outviolations of weak supervenience and certain patchworkworlds as well.

Another potentially interesting sort of constraint isepistemic. It is sometimes said that normative principlesmust be knowable, or more modestly, that since it is of theessence of normative principles to guide the conduct ofrational creatures, it lies in the nature of (say) moralpermissibility that the principles of permissibility in w33 For example, a world of two-way eternal recurrence in which the natural history of the world is repeated endlesslydown to the last non-normative detail, but in which an act utilitarian epoch is followed by (say) a Kantian epoch.

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must be principles that rational creatures in w couldreasonably believe. Consider the world that isnaturalistically like this one, but in which the moralprinciples shifted imperceptibly at the turn of the lastmillennium. It seems fair to say that if there were such ashift, it would be radically undetectable: no one could everhave reason to believe that the moral principles exhibitedthis patchwork character. If that is so as a matter ofmetaphysical necessity, then the epistemic constraint onmoral principles would brand this patchwork worldimpossible. It might even rule out vile worlds, like theworld in which Caligula’s moral principles are true. Butnote: this constraint can only have these consequences iftwo conditions are satisfied: not only must it lie in thenature of (say) moral permissibility that the principles inwhich it figures must be rationally accessible; it must liein the nature of epistemic rationality or some related notionthat there is no possible world in which people have reasonto believe these bizarre principles. And it is unclear (tosay the least) whether such principles are plausibly built-in to the natures of the epistemic notions.

That said, I should emphasize that it would not be adisaster, or even a serious objection to the view, if therewere no strong essentialist constraints of this sort onmoral principles. The bizarre worlds we have been discussingappear to be consistently describable. To call themmetaphysically possible is just to say that this appearancewould survive perfect knowledge of the essential truths. Butso far as I can see, nothing hangs on how these worlds areultimately classified. Here is an analogy. Focus on thephysical probabilities of ordinary events. If we are non-humeans about the laws of chance, the actual mosaic ofparticular fact is consistent with a wide range ofassignments of probabilities to events, including bizarreassignments on which the half-life of U238 changedimperceptibly on December 31, 1999. It’s an open questionabout whether a bizarre law of this sort is ruled out by theessential truths. But what would hang on this determination?The metaphysical classification of worlds that include

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piecewise laws of chance would make no difference to physicsor to more down to earth questions in the philosophy ofphysics. It may be interesting in its own right, but it’snot the sort of issue on which the credibility of ametaphysical theory of chance should turn. I take the sameview about the classification of worlds with bizarre morallaws.

At this point the reader will protest that themetaphysical classification of these bizarre worlds mattersfor moral epistemology. The various worlds we have beenimagining amount to skeptical scenarios: worlds in which weform our moral beliefs just as we actually do (since thefacts of belief-formation are natural facts, and these areheld fixed) and yet our methods lead us wildly, massivelyastray. It’s not news that our moral methods are fallible.But surely it should have some impact on our confidence tobe told that there are genuinely possible worlds — worlds wehave never considered and never paused to exclude — in whichwe diligently employ our best methods and yet come nowherenear the truth, or so the objection runs.

Now there are versions of this challenge that we caneasily shrug off. The mere metaphysical possibility ofundetectable error should not undermine our confidence anddoes not prelude knowledge. That is the great lesson of 20th

century antiskeptical epistemology. The countermoral worldswe’ve been discussing are to moral epistemology what evildemon worlds and the like are to the epistemology ofperceptual knowledge: their existence shows that our methodsare fallible and nothing more.

There is however a version of this challenge that isharder to shrug off. If the metaphysical picture I havebeen advancing is correct, our beliefs about pure moralprinciples are not sensitive to the pure moral facts.Suppose P is a true moral principle which we have come tobelieve as a result of the most scrupulous philosophicalenquiry. Now ask what we would have believed had P beenfalse. My view entails that there are worlds of this sort inwhich the non-normative facts, including the facts about ourbeliefs, are just as they are, and these worlds are closer

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to the actual world than worlds in which P is false and thenatural facts are also different. (This follows from ourframework on the assumption hat the normative facts play norole in explaining the natural facts.) And that means thatour beliefs in pure moral principles would have been just asthey are even if the pure moral facts had been quitedifferent.

So far this is just an observation. It amounts to anobjection only if it suggests that our beliefs in moralprinciples must be unjustified, or fail as knowledge, ifthey are insensitive in this way. This is an enormousquestion that we cannot address here fully, so I’ll bebrief.

First, even if it is plausible on reflection that thereis a sensitivity constraint on knowledge or justified beliefin many areas, it is a step to hold that such a constraintapplies across the board. A perfectly general sensitivityconstraint entails (given the metaethical view I have beendefending) that even when someone accepts a true moralprinciple for what we normally regard as good reasons, hedoes not know (or justifiably believe) that principle.Confronted with such a case, we will face a choice: acceptthe across-the-board sensitivity requirement and deny thatthe case is a case of knowledge, or treat the fact of moralknowledge in the case as a counterexample to the across-the-board sensitivity requirement. And to put the point asconcessively as possible, it is at least unclear which ofthese theoretical options is to be preferred. Philosophicaltheories of knowledge must be liable to refutation bycounterexample. If some theory tells me that I can’t knowthat it wrong to cause intense pain in a non-consentingvictim for fun (because my belief in this fact is notsensitive to the fact that makes it true), I am inclined tosay: so much the worse for your philosophical theory, sinceI certainly do know/justifiably believe this moral fact.34

34 This is analogous to the response to epistemological challenges to Platonism based on the causal theory of knowledge in (Burgess and Rosen 1997).

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Second, the sensitivity challenge does not just arisefor my view, but also for what I take to be its closestcompetitor, the sort of non-reductive normative realism thatembraces supervenience and non-contingency (and so rejectsthe essentialist account of metaphysical modality). Thesefamiliar views hold that pure normative principles aremetaphysically necessary. But we can still apply a non-trivial sensitivity test in this domain, provided we allowfor non-trivial counterfactuals with impossible antecedents.If we do, then it is highly plausible that the non-reductiverealist will have to say that had the pure moral principlesbeen different (per impossibile), our beliefs would have beenjust as they are. So either the problem sinks both sorts ofrealism or it sinks neither. Moreover, the verdict that itsinks neither will be more secure in this case, since thecost of maintaining an across-the-board sensitivityrequirement will be quite high. The truths of puremathematics are presumably metaphysically necessary truths,but we can coherently suppose many of them to be false byconsidering worlds in which there are no mathematicalobjects of any sort, worlds in which all sets are finite,and so on. Many of our mathematical beliefs will then failthe sensitivity test: if there had been no numbers (orinfinite sets), these beliefs would have been just as theyare. Does this show that our ordinary mathematical beliefsare unjustified, or that they don’t amount to knowledge?Perhaps. But it is at least equally plausible to say thatit shows instead that there is no across-the-boardsensitivity requirement in epistemology.

Of course this companions-in-guilt gambit can beblocked by insisting that counterfactuals withmetaphysically impossible antecedents are trivially true.But the fact that the test can have no application giventhis assumption suggests that the sensitivity requirementitself is fishy. There is a good epistemological questionabout how we can know whether mathematical objects exist, orwhether God exists, or whether some putative moral principleis true. But it is hard to see how our epistemic tasks inthese areas becomes easier when the fact that interests us is

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non-contingent. So long as the truth in question is not aconceptual truth, we still face the challenge of determiningwhich of two (or more) epistemic possibilities is actual onthe basis of whatever indirect evidence we can muster.There is no a priori guarantee that our method will succeed.So even when we have employed it correctly we can alwayswonder whether the actual world and all of the other possible worldsare worlds in which our method leads to false belief. It’shard for me to see how it can be comforting to be told thatif we have gotten it right, our belief is (trivially)sensitive to the facts. It remains the case that our methodis not tracking the facts: In these non-empirical domains wedo not believe what we believe because the facts are as they are.And my strong inclination is to say that either this orsomething like it is a general constraint on knowledge, inwhich case every form of non-reductive realism aboutcausally inert features of reality is undermined, or it isnot, in which case there is no special epistemologicalproblem for any such view, including the view of thenormative facts we have been discussing.

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