On the definition of observation as justified true perception

Alessio Gava

Universidade Federal de Minas Gerais

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Abstract: The primacy of the act of observation, one of the hallmarks of empiricism, found

new life in the centrality of the distinction, made in Bas van Fraassen’s constructive empiricism,

between observable and unobservable. As Elliott Sober (and others) pointed out, however, it is

not clear what van Fraassen understands by observing an object. Worse, the Dutch philosopher

does not seem to consider that a clarification of this point is necessary. This, of course,

represents an important lacuna in a position generally considered as the main reference for

modern empiricism. My goal is to take up again the counterfactual conditionals characterizing

perception that Otávio Bueno presented in 2011 on this journal, and also to consider the

observability and the existence criteria proposed by Filip Buekens and Michel Ghins, in order to

get to a definition of observation that should give van Fraassen’s observability concept the

support it actually lacks, but without presenting itself as an ad hoc solution.

Keywords: Observation. Perception. Observability. Relevant counterfactuals. Constructive

Empiricism. Van Fraassen. Buekens, Bueno. Ghins. Noë.

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Constructive empiricism, the anti-realist vision of science that Bas van Fraassen

proposed in his seminal book The Scientific Image (1980), is based on the possibility,

admitted by his epistemological position known as voluntarism, of maintaining a

different attitude with respect to the different parts of a scientific theory: belief

(epistemic), to be hold towards its empirical substructures, that is, those parts of the

models of the theory that directly represent the observable aspects of the world, and

mere acceptance (pragmatic), something that can be roughly compared with ‘pretending

it is true’, to be maintained when the theory does not speak about something that is both

observable and actual.

As it can be inferred, there is a more basic distinction that is crucial for the

empiricist position of the Dutch philosopher: that between observable and

unobservable. Furthermore, being an empiricist means to recognize the primacy of

observation and this ensures the possibility of maintaining a ‘strong’ attitude with

respect to the beliefs based on it (and, as a consequence, with respect to the observable

The present work is the translation of an article originally published (in Portuguese) on Scientiæ Studia,

São Paulo, v. 13, n. 1, p. 123-141, 2015. Any comments (or suggestions for a better translation) are

welcome.

entities). In this regard, van Fraassen wrote: “It is possible to remain an empiricist

without sliding into skepticism, exactly by rejecting the skeptics' pious demands for

justification where none has to be had” (van Fraassen 1989, 178).

There exists, apparently, a (structuralist) way of characterizing the empirical

substructures by means of the so-called ‘partial models’ that would dismiss the appeal

to the notion of observability and be more convenient from the point of view of the

structure and the dynamic of the theories. For van Fraassen's constructive empiricism,

however, the concept of empirical adequacy is crucial, as one of the pillars of this anti-

realist position is the idea that “science aims to give us theories which are empirically

adequate” (van Fraassen 1980, 12). The notion of observability is then so essential for

constructive empiricism that in any attempt to apply the partial structures-based

approach to it, particularly to the notion of empirical adequacy, there is a reference to

the observable aspects of the world or to the empirical phenomena - whereas they are

the same thing (see, for example, Bueno 2014a and 2014b). Moreover, it is difficult to

see how a partial model could constitute an empirical substructure of a scientific theory

without any appeal to the notion of observability, considering that the empirical

substructures are defined by van Fraassen as being certain parts of the models of the

theory, candidates for the direct representation of observable phenomena (see van

Fraassen 1980, 64).

Carnap (1950) explicitly stated that the reality of the external world thesis is a

pseudo question; nowadays this seems to be underlying, not even very implicitly, the

debate between realism and anti-realism (and Philosophy of Science in general). But

neither in the last century was there someone who, at least in Philosophy of Science,

called the existence of a mind-independent reality into question. Talking about scientific

realism, Chakravarrty says it is the position according to which “scientific theories

correctly describe the nature of a mind-independent world” (Chakravartty 2007, 4), but

this point is certainly partaken by van Fraassen's constructive empiricism (whose anti-

realism only means not accepting the idea that scientific theories correctly describe all

the aspects of this world, as there is no way to determine the truth value of the

assertions about its unobservable aspects, and has nothing to do with denying the reality

of the material world). Van Fraassen wrote: “I try to be an empiricist, and as I

understand that tradition (...) it involves a common sense realism in which reference to

observable phenomena is unproblematic: rocks, seas, stars, persons, bicycles...” (van

Fraassen 2008, 3). But Kosso (2006) and Chang (2004), among others, consider that

observation provide information tat we cannot control at will and therefore has to be

understood as being about an external and mind-independent world. The same thesis is

implicitly assumed in this work.

Some empiricist positions (even if not all) – and van Fraassen's constructive

empiricism can be contemplated among these – consider sense perception as the point

of departure for our knowledge of the external reality, which seems to be reasonable (or

even obvious).1 As a matter of fact, the confidence in the responses of our sensory

system to the external stimuli is innate and motivated by the ability to adapt to the

environment that human beings developed along their evolutionary history. Without this

capacity, the human race would have gone extinct.

Nancy Cartwright considers that this explains van Fraassen's belief in the

observables and that, for the same reason, these beliefs do not need a justification. We

have a special primitive justification, not epistemic, for the formation of beliefs about

what is observable: they help us control all the experiences and the perceptions which

affect us (see Cartwright 2007, 40-44).

This does not mean that our sensory system is taken as ‘surefire’ by the

constructive empiricists, but human beings are usually capable of recognizing when a

perception is trustworthy or not and even to correct it, if necessary.2 What Paul Grice

said more than fifty years ago still stands, then: “when, in normal circumstances, it

looks to me as if there is table before me, I am entitled to say flatly that there is a table

before me, and to reject any demand that I should justify my claim until specific

grounds for doubting it have been indicated” (1961, 150).

But how can we know when a perception is ‘successful’ and can legitimately be

considered an instance of observation? The point is not only to exclude ‘extreme’ cases,

like hallucinations, which keep philosophers of perception so busy, but also common

episodes, as when, by touching the wooden surface of a table with our hand, it appears

to be ‘less cold’ than the metal leg of the chair on which we sit.

1 The expression ‘point of departure’, when used about constructive empiricism, must be taken cum grano

salis, as it could suggest that van Fraassen is a foundationalist, while he explicitly denies the possibility of

a foundationalist epistemology. 2 According to Paul Humphreys, the emphasis on the unaided senses as a source of reliable information is,

in part, the result of our familiarity with the circumstances under which they ‘fail us’: “We ordinarily

assume that the use of our senses in situations outside ideal contexts is relatively unproblematical, but this

is based on our quite refined sense of the conditions under which the evidence of our senses becomes

unreliable” (Humphreys 2004, 40, tradução nossa). When we feel there are no reasons to distrust it, which

happens by default when it is the case, putting confidence in our sensory system is the norm.

It seems then appropriate to consider that we only observe when a perceptual

experience is produced by the interaction between perceiving subject and perceived

object so that the properties of the latter are correctly represented in this experience, as

suggested by Bueno (see Bueno 2011, 278). In order for this to happen, there has to be a

causal-type relation between how things actually are and the perceptual experience

itself. But merely believing that perception is the terminus of a causal chain beginning

with the perceived object is insufficient (see Grice 1961, 121).

In fact, even if, at the end of the day, appearances are our only guide to reality,

what seems to be the case cannot be taken as necessarily corresponding to what is the

case. There exists the problem of getting from appearance to reality (just meaning that,

because of the fallibility of our sensory system, there can be a hiatus between ‘how

things appear to be’ and ‘how things actually are’. It is certainly not Grice’s intention –

and neither ours – to deal with metaphysical questions like the difference between

phenomena and noumena). In order to solve it, Grice proposed a version of the causal

theory of perception according to which a subject X perceives M if and only if M is

causally responsible for a state of affairs accurately reported by X (see Grice 1961, 151-

152).

Alva Noë summarizes Grice's causal theory as being the assertion that a subject

S sees that o is F if and only if S has the visual experience of o as being F; o is F; and

the experience of o depends, causally, on o being F (see Noë 2003, 93). The same

criterion can obviously be applied, mutatis mutandis, to all the senses.

Grice's characterization does not seem to capture (at least not completely) what

happens in perception, though. The very act of seeing does not correspond to merely

having a visual experience, although Grice (correctly) emphasizes the need for a causal

dependence between the experience and the perceived state of affairs.

Besides, according to Noë's ‘diagnosis’, Grice's causal theory is flawed. The

reason is that, even if it specifies the right kind of causal relation, it neglects the content

of the perceptual experience that is about the relation between the subject and the object

of perception. In a veridical and genuine experience the right sort of counterfactual

supporting dependence must be maintained both in the factual dimension and in the

perspectival one. On the one hand, were experienced things different, they would appear

different to us. On the other, were our relation with the experienced things different,

these would appear different to us (regardless of they having changed or not).

Perception depends both on how things are and on what the perceiving subject

does, as not only is it a causal concept, but a kind of action as well. When we perceive,

what is kept track of, besides the way things are, is how our relation with them changes.

But this is not taken into account in Grice's characterization, that is then flawed. It

constitutes a necessary, but not sufficient, condition for the subject to have a genuine

(veridical) perceptual experience (see Noë 2003, 99).

According to a different proposal put forward by Bueno, the perception of an

object depends on the satisfaction of the following counterfactual conditionals:

(C1) Had the scene before our eyes been different (within our cognitive device’s sensitivity

range), our perceptual experience would have been correspondingly different. (C2) Had the

scene before our eyes been the same (within our cognitive device’s sensitivity range), our

perceptual experience would have been correspondingly the same (Bueno 2011, 278, our

translation).

These conditionals seem to take into account the two dimensions that, according

to Noë, concur to form the content of a perceptual experience. However, since in the

paper where they have been proposed there is no mention of the possibility of the scene

before us changing because of a displacement or a movement of the perceiver (perhaps

for this having been considered obvious or implicit), we found it opportune to make this

possibility explicit. We then say that a perceptual experience constitutes a legitimate

perception if the following conditionals are satisfied:

(C1) Had the scene before our eyes been different (within our cognitive device’s

sensitivity range), because something in the way things are changed or because of a

displacement of our eyes in relation to such things, or for both reasons, our perceptual

experience would have been correspondingly different.

(C2) Had the scene before our eyes been the same (within our cognitive device’s

sensitivity range), because nothing changed in the way things are and no displacement

of our eyes in relation to such things took place, our perceptual experience would have

been correspondingly the same. (Again, the same criteria can be applied, mutatis

mutandis, to all the senses.)

These counterfactual conditionals can legitimately be called ‘relevant’ since

both in the factual and in the perspectival dimension the correct form of counterfactual

dependence is maintained, in accordance with Noë's desiderata (and in accordance with

what actually happens in perception). For the same reason, not only are they necessary,

but also sufficient for the subject to have a (veridical) ‘genuine’ perceptual experience.

Still, as Noë points out, some skeptic could imagine fictional situations (to

define which highly unlikely would be euphemistic, at the very least) satisfying these

counterfactuals, but in which perception does not happen 'the normal way’. The best

answer, in cases as such, according to Noë, is to classify these perceptions as genuine,

and not ‘only’ veridicals, because what counts is the satisfaction of the aforementioned

conditions, necessary and sufficient to classify a perception as authentic, and not

whether it happens the ‘natural’ and common way or not. This does not seem correct,

though, as it will be seen. The best way to answer, on the contrary, seems to be ignoring

the situations that the skeptic invites us to imagine. As they say, better stopping the

skeptic at the front door, because once she is in there is no way to block her ‘destroying

power’. It is a legitimate option, considering the artificiality of the examples.

As a matter of fact, if only by imagining unachievable circumstances can we

think of cases where the relevant counterfactual conditionals are satisfied, while at the

same time the question whether these are instances of genuine (veridical) perception

remains open, then this indirectly confirms that these conditionals capture in a correct

and satisfactory way what happens in ordinary (even uncommon) cases of perception. It

is not because of Noë's examples being ad hoc, then, that they can legitimately be

ignored, but because, as they do not represent possible events (that can or could have

happened), they do not constitute a real confutation of this characterization of

perception.

In other words, the situation here is different from the well-known

counterexamples Gettier put forward for the definition of knowledge as justified true

belief. Noë's examples do not refute the characterization of perception by means of the

relevant counterfactual conditionals, while Gettier's counterexamples stress the

inadequacy of a definition of knowledge as justified true belief.

To sum up, if all the skeptics can imagine as circumstances under which the

relevant counterfactual conditionals ‘fail’ are nothing more than ‘science fiction

contexts’, then they can certainly be considered as misfiring examples and disregarded.

We should only take into account events that happen in ‘possible worlds’.

However, it is worth pointing out that the satisfaction of the first counterfactual

condition has to do with the fact that, again in Noë's words, “in perception, the world

acts on us, and we act right back” (Noë 2003, 100). Perception is an action and, as such,

involves our body as a whole, including all our senses. Our ‘analytic spirit’ and a need

for simplification (the likely ‘mother’ of this spirit), which seems to be inevitable if we

want to deal with phenomena whose complexity would otherwise make unviable our

attempts to understanding, have us analyze perception as an action that can be

performed by means of a sense organ alone. It is then common to speak of visual

perception, tactile perception, etc.

Now, if perception is a conscious activity (and for this reason it is correct to say,

for example, that I did not hear the telephone ringing, last night, because I was

sleeping),3 conscience has to do with the subject (her body, at least) being awake and

vigilant. This means that it is the body as a whole that is active when an external

stimulus affects it and that cooperates so that it is possible to decode the signal and the

information that this stimulus ‘delivers’ to the subject.

If Pablo says “I have just seen Salvador in front of the gallery”, he then is

stressing the visual aspect of the interaction he had with his colleague, but the two

might have also talked about the last painting Manuel did or the smell of guava (his

friend's favourite fruit) might have helped Pablo realize it was Salvador, etc. Not to

mention that, of course, Pablo's body as a whole acted in order for perception to be

‘successful’: the eye muscles and the ones of the neck to direct the look, many other

muscles to keep standing (supposing this was the case) and, probably, other senses,

besides vision, to help him have an idea of Salvador's spatial position. Analyzing

Pablo's perception as if it only involved his visual apparatus would mean to focus on

one aspect of it, but this could not be considered an exhaustive report.

This gets even more evident when, for some reason, we want to be sure of what

we perceive. If we hear the voice of someone we know while walking on the Avenida

Paulista, we instinctively turn our head and look at him. When, in Switzerland, we got

out of the school after it snowed the entire afternoon, we took the snow off the plate in

order to know which car was ours. If I want to listen to a song I like, on the radio, and

from where I am I cannot hear clearly, I get closer to the device or turn the volume up.

3 This is van Fraassen’s opinion, for example, since experience, according to him, consists in the events

that happen to a subject of which she is aware (see for example 2001, 158 and 2008, 108 and 364,

footnote 20).

Maybe we cannot help, for ease of description and comprehension, reporting the

experiences of these examples by merely stressing the involvement of a sense organ

alone (“I heard Enrico calling me, yesterday, on the Paulista”; “I saw a car identical to

mine, parked nearby”; “I listened to Paolo Conte's new song, this morning, on the

radio”), but to only stick to that is an understatement and can lead to get a wrong idea of

what a perception is.

According to Michel Ghins, if the question of what it is for an object or a thing

or whatever to exist pertains to the domain of metaphysics, the question of what

grounds we can rationally adduce in favour of the existence or reality of something has

to do with the justification of our beliefs and, being so, it pertains to the domain of

epistemology. But the two questions cannot be completely separated and if I can justify

my belief in the existence of a blue pen before me just by saying that I see it, as an

empiricist would do – just like van Fraasen is sure that there are no flying horses

because none of them has ever been seen (see van Fraassen 1980, 15) –, it is also true

that the pen must satisfy some criteria, so that I do not have any doubt about its

existence and about the fact that I am not hallucinating. Among them, according to

Ghins, there is an invariance criterion: “Some objects can be moved in space while

retaining, according to what we observe, their identity. Or we can move around them,

while feeling sure that we still perceive the same object” (Ghins 2005, 96).

This criterion, which is ontological, is certainly in harmony with the proposed

counterfactual conditionals, despite these being epistemological. As a matter of fact,

both according to Ghins’s criterion and to Bueno’s counterfactuals, there is a relative

displacement between the observer and the object (or state of affairs) perceived, which

makes it feasible for the subject to keep track of the latter, so that she can feel sure that

she still perceives the same object (which retains, according to the observer, its

identity).

We can then infer that something more than a simple look is involved in

perception. It is an action, involving the whole body.

When, on the other hand, we are in no conditions to verify the invariance

criterion, it can be legitimate to maintain a cautious and critical attitude towards what is

(supposedly) being detected. This can be the case when the matter is the use of

instruments in the everyday routine of the scientists. With regard to what is detected by

using a microscope, for example, there exist reasons to keep cautious, because, at the

very least, as Ian Hacking admitted, to say that a microscopic entity has been observed

‘stretches’ our ordinary concept of observability (see Buekens 1999, 25).

Buekens, having in mind a characterization of observable object given by

Strawson and Evans and retrieved by Peacock, endorses the criterion, which almost

seems ‘custom made’ for van Fraassen, according to which an object must permit to be

observed and identified from different angles.

It is crucial to our conception of an observable object that it be the centre of a perceptual

polygon - it can be perceived or observed from different angles (when the observer moves) and

remain observable when it moves in space. (That such a perceptual polygon exists for

microscopic objects is suggested by Hacking in his argument from the grid, but Van Fraassen

correctly points out that Hacking is confusing one object, seen from different perceptual

positions (the polygon case), with seeing two objects from similar positions.) It comes with our

concept of an observable object that it can be observed - identified - to be that object from

different perceptual angles. The observer must be able to place it at the centre of a perceptual

polygon. (Buekens 1999, 26).

Microscopic entities, like electrons and cells, do not seem to satisfy this

criterion. According to Buekens, there is only one perceptual angle from which it is

possible to have access to them, the one provided by the instrument. Therefore, they do

not fit the proposed observability criterion – note that in this case the reliability of the

instruments is not at issue.

Buekens still adds:

Our concept of an observable object is geared to the practice of observing mundane,

macroscopic objects and events and our capacity to keep track of them as they, or we, move in

the space in which that object is located. Stretching the concept of observability beyond these

limits involves imagination (Buekens 1999, 27).

Now, to say that this criterion, which appears to be reasonable and totally in tune

with the invariance one, allows to deny the observability of a cell seems wrong, as this

can be detected from different perceptual angles, both using a single instrument and

using different ones. But what is interesting to point out here is the recurrent idea of

perception as an action in which the suject (her body as a whole) is active. There is a

series of activities the perceiving subject performs in order for the perception to be

successful. There is not mere passivity to the external stimulus.

Note that Buekens’s criterion is epistemological, while the invariance one is

ontological; anyway, the two are certainly in harmony. What has been said with regard

to the connections between Ghins’s criterion and Bueno’s counterfactuals applies to

them too. As a matter of fact, even in the perceptual polygon argument, there is a

relative displacement between the observer and the object (or state of affairs) perceived,

which makes it feasible for the subject to keep track of the latter, so that she can feel

sure that she still perceives the same object (which retains, according to the observer, its

identity).

In view of all this, it seems possible to say that perception, even when described

in terms of a sense organ alone (“This guava tastes bad, Pablo!”), is actually the

outcome of a complex action (or of a series of actions) and it is the conscience of this

action as a whole that contributes, together with the conscience (which can be implicit)

that the relevant counterfactual conditionals are satisfied, to make the subject know that

he had a veridical and successful perception.

Charles Taylor writes:

our perception of the world is essentially that of an embodied agent, engaged with, or at grips

with the world. (…) The claim is not just that perception depends causally on certain states of

our bodies - that I couldn't see if my eyes were not in good condition, or the like. The claim is

rather that our perception as an experience is such that it could only be that of an embodied agent

engaged with the world (Taylor 1979, 154).

It is worth noting that this idea of ‘embodied agent’, which, according to Taylor,

is present in Kant and that seems to be present also in contemporary authors we

mentioned and can consider as pertaining to the analytic tradition (with all the care that

assigning a label in philosophy requires), that is, Filip Buekens and Michel Ghins, is

also defended by an important philosopher of the continental tradition, Maurice

Merleau-Ponty. In his Phenomenology of Perception (1945), Merleau-Ponty says that

perceptual experience stems from the relation between the body (as a whole) and the

world and he even talks about how external objects can only appear to the subject in

perspective, but in a way that is taken into account by perception itself. And we have

already seen the importance that Alva Noë gave to this aspect of perception in recent

times. If, on the one hand, this conception of ‘perceptual body’ can provide a suggestive

example of ‘analytic/continental’ parallelism, on the other hand it can be seen as a

cross-cut concept with respect to the two traditions (but also to the debate between

realism and anti-realism in Philosophy of Science) and, for this very reason, as a neutral

and important point of departure for a discourse about observation.

Taylor also says that we can see Kant in the transcendental deduction starting

from the insight that we must able to distinguish, in experience, an objective order of

things from a merely subjective one (see Taylor 1979, 151). Now, sure van Fraassen, as

an empiricist, does not call on transcendental arguments. However, in this case, he

seems to be in tune with Kant's (and Taylor's) idea, as the following excerpt taken from

“Constructive Empiricism now” (2001) shows:

My experiences are the events that happen to me of which I am aware. Such an event has two

sides, so to say: what really happens to me and the spontaneous judgement I make in response,

which classifies that event in some way. In good cases the two coincide, but often they do not.

(van Fraassen 2001, 158).

Or also, as stated in another paper: “Experience is, phenomenologically,

experience of myself among and confronted by things and events – perhaps it cannot be

otherwise, perhaps this form is a precondition for the very possibility of coherent

experience” (Ladyman et al. 1997, 320).

Being conscious of what is experienced is the same as saying, in the case of

perception, that the agent has a clear notion not only of what the object of perception

was, but also of how we, as perceiving subjects, are actively involved in this action. It

also means being ‘self-aware’ and feel that the whole body is active in perception,

concurring for it to happen. This also allows distinguishing between an objective order

of things (how things are) and a merely subjective one (how we respond to what

happens to us, but also how and how much we are involved in this perception).

But most important is the fact that this conscience also entails knowing if all the

conditions for perception to happen according to our goals have been satisfied or not

and if, once accomplished that, perception actually happened as ‘planned’ or if the

object of perception was something else (and what it was). This kind of conscience is

usually not ‘superficial’ and our perceptions happen mostly by default, but it is

‘available’, in case it is necessary.

Locke already said that, when pressed about a belief he holds, the knower should

be able to tell us about the way in which it arose within him, for example by telling us

about his experiences (see Nagel 2000, 347), but this also means that, as Grice said, in

ordinary cases there is no need to justify our observation-based beliefs. Not even to

ourselves. We have already seen that, according to van Fraassen, it is possible to remain

an empiricist without sliding into skepticism, by rejecting the skeptics' demands for

justification where none has to be had. However, as Jennifer Nagel wrote, when van

Fraassen claims to be ‘not interested in warrants’, he does not mean to suggest that they

do not exist. They dwell in the ‘immediacy’ of experience (see Nagel 2000, 364). In van

Fraassen's words: “we can and do see the truth about many things: ourselves, others,

trees and animals, clouds and rivers – in the immediacy of experience” (van Fraassen

1989, 178).

In a genuine perception, we are conscious of it being actually genuine, because

the relevant counterfactual conditionals are met and because we have 'kept alert' the

whole time, aware of the fact that the conditions for the perception to happen veridically

were satisfied, knowing what it was that we saw and being sure of that because the

whole body concurred to accomplish this action, in a synergy that, in ordinary cases,

involves more than one sense at the same time.

This ensures that the interaction with the perceived object be qualified as thick

epistemic access, following Jody Azzouni’s proposal (2004). Peter Kosso (2006) and

Otávio Bueno (2011) consider Azzouni’s criteria as the way to distinguish between

inference and observation – that, according to them, as well as to Azzouni, can happen,

contra van Fraassen, also in cases in which the access to the entity can only be obtained

by means of some instrument. As a matter of fact, what’s important, according to the

two authors, is not whether in the detection there has (or has not) been also the

intervention of an instrument (like a microscope, a telephone or a stethoscope), but

whether the kind of access that has been used provides an adequate epistemic

justification for the collected information. While endorsing Azzouni’s criteria of

independence (and robustness), refinement and monitoring, however, Bueno

demonstrates that the counterfactual conditionals he proposed guarantee the satisfaction

of the three requirements and so are more basic (see Bueno 2011, 279-281).

Moreover, not only does a perception in which the subject is conscious of how it

happened and of the fact that the relevant counterfactual conditionals (in the more

detailed version here presented) are met qualify as a genuine (and veridical) one,

namely, as an observation, but it also produces knowledge, according to the empiricist

identification between observability and knowledgeability. As Bueno writes, “not only

should perception offer a reliable information generation process, but it must be such

that one knows that the process is indeed reliable; or, at least, we should have access to

the factors sustaining its reliability” (Bueno 2011, 281, our translation).

In the case of our sensory system, we know that it is reliable, but not infallible.

However, as said before, we are usually capable of ‘perceiving’ when it is delivering us

unreliable information and, in general, of correcting this (changing the perspectival

conditions, using an instrument with a higher sensibility than that of our senses, asking

to another person if she is perceiving the same, etc.). In other words, we do know if the

process is happening in a reliable way or not (and even how to correct it, usually, if

necessary).

This, by the way, seems to also be the case for many instrumental detections. As

a consequence, according to Bueno and many others, one could trace the observable/

unobservable line not where van Fraassen does, but elsewhere. Many entities that the

Dutch philosopher classifies as unobservable could then be encompassed among the

observables, as in the case of the cells.

Noë's examples, instead, do not satisfy this internalistic requirement. He places

on an equal footing ‘genuine’ prosthetic perceptions (as when, for example, a deaf

person can hear thanks to a hearing aid) and ‘perceptions’ that are veridical because of

the intervention of intelligent agents (surgeons, angels, micro persons). One of the cases

Noë imagines (or mentions) is that of an angel floating next to a person and acting in

such a way that the latter's experiences depend both on how things are and on what the

person does, satisfying the relevant counterfactual conditionals – because of the angel's

intervention and not because of the functioning of the person's sensory system (see Noë

2003, 97-98).

According to Noë, this – and the same goes for the other, totally analogous,

examples presented in his paper – can be considered an instance of genuine (prosthetic)

perception, for the reasons we have seen before. This does not seem correct, though, as

was also said before. In cases as those of a perception that is always veridical because of

the intervention of an angel who guarantees a correlation between the state of affairs in

the world and what is ‘perceived’ by the subject, so that the relevant counterfactual

conditionals are met, we can say that the subject thinks that she knows that those

conditionals are met, but that this is actually not the case.4

In Noë's examples of ‘anomalous perception’, it is certainly not the case that the

subject has access to the factors warranting the reliability of the information generation

process, therefore it is not correct to qualify them as instances of perception. It would be

correct, instead, to say that they are ‘veridical hallucinations’ (and, consequently, that

Noë's attempt to complement Grice's causal theory, in order to separate hallucinations

from genuine perceptions, failed).

4 I thank Prof. Bueno for the clarification about the examples Alva Noë proposed in his article.

Considering the intimate relation that, for an empiricist, exists between

observation and knowledge, it seems then possible to give a ‘definition’ of the former,

having some analogy with the ‘classic’ definition of knowledge as justified true belief.

We will say that:

S observes e if and only if S (justifiably) knows that she is perceiving e,

where perception is conceived as the satisfaction of the aforesaid relevant

counterfactual conditionals and the subject S knowing that she is perceiving e merely

corresponds to her being conscious (even implicitly, as was also said before) that these

counterfactuals are met. In this regard Bueno writes that this ‘internalistic requirement’

means that “not only is the counterfactual conditional satisfied, but we also know (at

least intuitively) that it is satisfied” (Bueno 2011, 284, our translation). This idea that

the awareness of the satisfaction of the relevant counterfactual conditionals can be

merely intuitive or implicit does not seem to be correctly captured by the classic

definition of knowledge as justified true belief and this makes explicit the fact that the

latter is not being used here, but only evoked because of a possible ‘structural’ analogy

with the proposed ‘definition’ for the act of observation. This also explains the use of

the locution ‘knowing that’, which might seem inappropriate, particularly to the eyes of

the endorsers of the ‘JTB definition of knowledge’. Therefore, the definition of

observation here proposed does not seem to inherit the ‘Gettier-like’ problems afflicting

the classic definition of knowledge.

Van Fraassen is one, among others, who clearly said that the classic tripartite

definition of knowledge should be abandoned, as it is a far more extensive concept than

the one ‘captured’ by that definition. Bueno, in turn, considers that the tripartite

conception of knowledge is inadequate and, for this reason, does not assume it in the

characterization of perception (including when this is instrument-aided). Moreover, with

regard to the internalistic requirement, the fact that the subject knows that the relevant

counterfactual conditionals are satisfied merely means that she is aware (is conscious)

of this - at times not even explicitly, as has been said. It is therefore a kind of

knowledge that does not seem possible to actually capture by the classic definition and

that can even be ascribed to animals and babies. It is an instance of non-propositional

knowledge, although, in the case of adults, it can result in the aquisition of beliefs and,

therefore, it makes sense to discuss about the justification of these beliefs that are the

result of a perception. Buekens and Muller (2012), inspired by Dretske and by

Buekens’s previous work, identify various levels in the process of observation, the

lowest being observation conceived as a mere record (something that can be performed

even by photographic devices) and observation as a record, but ‘with conscience’ of the

event (achievable by human beings and other animals) and the highest being ‘doxastic-

oriented’ observation and ‘doxastic’ observation (the same as Dretske’s observing that).

The second level they identify is worth noting, as the capacity of becoming conscious of

a certain object, because of seeing it, pressuposes the possession of a mind and can

therefore be only partaken by (some) living beings (see Buekens & Muller 2012, 94-

98). It seems possible to say that, for van Fraassen, to observe coincides (or starts) with

this second level of seeing Buekens and Muller identify (observation as a record, but

‘with conscience’ of the event), but that, unlike them, he considers that this can only be

achieved by a human being – because “observers are potential believers”, as William

Seager wrote (Seager 1988, 181). Nevertheless, what is worth stressing here is the fact

that if by ‘knowing that’ (something is the case) we just mean ‘being aware’ (that

something is the case), then there are authors who consider that this kind of knowledge

can definitely be ascribed even to non-linguistic animals.

Moreover, from this characterization of observation it follows both that “S

perceives e (veridically)” and that “e (is the case)”, because both the verb to know and

the verb to perceive are success ones. Thus the analogy with the classic (tripartite)

definition of knowledge is established.

The condition “e (is the case)” has to do with how things are: I can perceive

(see, touch, smell, lick) the ice cream before me only if there actually is an ice cream in

front of me; were this not the case (if it is a hallucination) I could not.

The condition “S perceives e (veridically)” has to do with the satisfaction of the

relevant counterfactual conditionals. If the ice cream before me keeps the same, the

representational content in my mind will keep the same; if anything changes (the ice

cream started melting, Pablo dislocated it because wanted to make a picture, Salvador

ate the guava flavour ball or I moved), then the representational content in my mind will

consequently change.

The ‘definition-condition’ in bold type, which contains the other two, has to do

with the fact that the subject S has to know that the relevant counterfactual conditionals

are met (this is the condition Bueno calls ‘internalistic requirement’). If, because of the

intervention of an angel, I veridically perceive that there is an ice cream before me and

am aware of the fact that any change in my relation with the ice cream results in a

change of my representational content, but have no idea that what ensures this reliable

correlation between the state of affairs and my representation of it is the intervention of

an angel, it then seems correct to say that I think I know that the relevant counterfactual

conditionals are met, but that it is actually not the case. In other words, in this case my

belief that I perceive (an ice cream) is not justified, as explained before.

If there still exists an identity between observation and knowledge, then

questions directly related to the latter, like the debate between internalism and

externalism and, more in general, the problem of the justification of our beliefs, can

affect a discussion about the former. We will not deal with it here, as this would mean

to deviate from the aim of this work and because a single study would probably not be

sufficient, but it seems clear that, when we talk of internalistic requirement (the subject

must know that she is perceiving veridically), this does not mean that internalism alone

can succeed in justifying our beliefs. A bit of externalism is necessary, in order to avoid

solipsism. Another subject, different from the perceiver, can for example warn the latter

that things are not the way she thinks they are. Or, on the contrary, can confirm the

truthfulness or the genuine nature of a perception. If no one told me that, in the Ishihara

Test, there is a number 8 written on the card, I would think that what I see is a coloured

picture with nothing on it. But even after having been informed that someone drawed

the number 8 there, I still cannot see it and, to me, the relevant counterfactual

conditionals are satisfied (as a matter of fact, I discovered that I suffered from a mild

form of daltonism only when I was 18). So, I still think that I am perceiving a coloured

card on which no one wrote anything. Nonetheless, what I am perceiving is a coloured

card on which there is a picture of the number 8. Moreover, I know that I cannnot

justifiably say that on the card there is only an abstract coloured drawing and nothing

else, because I am aware that I suffer from a mild form of daltonism. Thus Salvador, if

his friend Pablo informs him that it is because of the intervention of a benevolent angel

that he can hear Edith Piaf singing, but that, as a matter of fact, he is now deaf following

the slug in the face he received from his muse Gala some time ago, will realize that he

thinks that he is hearing the famous French singer, but that actually he is not. Finally, as

a last example, let’s recall the recent case, that happened in the interior of the state of

São Paulo, of a wake during which the person who was (supposedly) deceased entered

the room (there had been an error in the identification of a dead body that was found, of

course). As it can be imagined, the relatives were astonished, when they saw ‘the

deceased’ entering the room where the body was waked. Now, in all probability, the

first person to see that individual must have doubted what he was seeing and drawn the

attention of the others, so that they looked to the same direction. Despite having a

veridical perception, the subject had reasons not to trust it and needed to compare it

with someone else’s, in order to corroborate it. Once confirmed that the other people in

the room were seeing the same as he did, the subject knew that he was actually looking

at the relative everybody thought was dead (and that he was not dreaming or

hallucinating).

Now, the problem of a characterization by means of a ‘definition’ is that, in

principle, there is the risk that the analogy with the famous tripartite definition of

knowledge is such that someone might find, even for observation, Gettier-like

situations, that is, cases of ‘justified true perception’ that are actually not instances of

observation. The analogy cannot be complete, though, because the ‘definition’ of

observation that was given (assuming that it can legitimately be called a definition) is

definitely descriptive, as it only tries to capture the characteristics or the properties of

this action, making explicit (and conforming to) what is commonplace and familiar,

while the ‘classic’ definition of knowledge 'has the look of' a stipulative definition.

Moreover, the internalistic requirement we talked about should prevent Gettier-like

situations from arising even for observation.

It is our conviction that this characterization of observation – as

(internalistically) ‘justified true perception’ – could, among other things, help

supporting constructive empiricism. As a matter of fact, several authors pointed out that,

despite the question of observability performing a crucial role for this anti-realist

position, it is not clear what it means, according to van Fraassen, ‘to observe’.

As claimed by Elliott Sober, for example, since the distinction between

observables and unobservables is central to the empiricism of the Dutch philosopher,

one might expect him to have provided an account of what is involved in observing an

object. In The Scientific Image, instead, he made it clear that it is an empirical question,

to be answered by science, and not a matter for philosophical analysis. But if it is an

empirical question to find out what the observational capacities are that human beings

have, this does not relieve empiricists of the obligation to say what is involved in the

action described as ‘observing something’ (see Sober 2008, 130-131).

The aim of this work was to put forward a characterization of observation that

enables ‘to fulfill this obligation’. It certainly is parasitic of a satisfactory

characterization of perception, but we believe that the one here proposed is enough to

support the Fraassenian distinction between observable and unobservable.

Moreover, even if it can be used as an argument to defend that entities which

van Fraassen notoriously considers unobservable, like paramecia, are actually

observable, it would be wrong to think that there does not exist a distinction between

observable and unobservable or that any entity postulated by science is, after all,

observable. The internalistic requirement, that the subject must know that the

information generation process is indeed reliable, blocks this possibility (see Bueno

2011, 289) and this guarantees that, thanks to the above definition, the foundation of

Constructive Empiricism is solid enough to sustain the philosophical construction of the

author of The Scientific Image.

Acknowledgments: The present work benefited from valuable conversations with Prof. Otávio Bueno, of

the University of Miami (EUA). I would also like to thank the anonymous referees of this Journal for their

useful comments on the first draft of this article.

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ALESSIO GAVA

Department of Philosophy

Universidade Federal de Minas Gerais

Belo Horizonte, MG – Brazil

alessiogava@yahoo.it