Ren Descartes(1596-1650 AD)Meditations on First Philosophy (1641)(Text, pp. 283-306)Revised, 1/7/07
Descartes ProblemThe problem of skepticism (D concentrates on 2 types of skepticism)
General skepticism: There are NO indubitable beliefs or propositions.
Skepticism concerning the existence & nature of the external world: The existence and nature of the external world cannot be known.Background
The overall structure of Ds Meditations(next slide)
GeneralCogito (existence of the I)(Med. I) (Med. II)Mind-Body DualismSkepticism God (no deceiver)External 1. My idea of God (III)World 2. My contingent(Meds. III-VI) existence (III) 3. The ontological argument (again) (V)
(That piece of wax)
Meditation IRadical (General) Skepticism
Epistemological Foundations & SuperstructureFalse Foundational BeliefFalse Foundational BeliefIf the underlying foundations of our beliefs are false, then it is possible that all of our beliefs are false too!Superstructural Beliefs(also false?)False Foundational Belief
Ds program of radical doubt Treat any belief that is to the slightest extent uncertain & subject to doubt just as though it is obviously false.Accept only those beliefs that are completely certain and indubitable.Work on the foundations of my beliefs.What are the underlying foundations of my beliefs?
Foundational Beliefs(common assumptions we make)Nave Empiricism: True beliefs are acquired through sense experience.
My beliefs are not products of insanity.
My beliefs are not products of my dreams.
Foundational Beliefs, contdPhysical objects: Even if we fail to perceive physical objects accurately, the primary [measurable] qualities of such objects (matter, extension, shape, quantity, size, location, time, etc.) are really real (i.e., physical objects do really exist).
Even if empirical beliefs are subject to doubt, mathematical propositions are indubitable (e.g., 3 + 2 = 5, a square has neither more nor less than four sides).
How does Descartes challenge each of the foregoing foundational beliefs?
How does he use the ideas of God and the Devil in building his case in support of radical skepticism?
Meditation IIDescartes Refutation of Radical Skepticism
Descartes refutation ofradical skepticismCogito ergo sum!What does this mean?
The most famous statement in the history of philosophy:I think; therefore I am.Discourse on Method (1637)
If I am deceived,
then I must exist!I cannot doubt the truth of the statement, I exist.I can't think that I am not thinking because then I am thinking; and if I am thinking, then I must exist. To doubt my own existence, I must exist!
Thus,Radical (general) skepticism is refuted.
Meditation II, contdThe Mind-Body Problem &Descartes Psycho-Somatic Dualism
Three metaphysical perspectives relevant to the mind-body problem
Metaphysical Dualism: Reality is two-dimensional, partly material and partly non-material (minds, ideas, souls, spirits, consciousness, etc.).
Metaphysical Materialism: Reality is nothing but matter-in-motion-in-space-and-in-time. There are no non-material realities.
Metaphysical Idealism: Reality is nothing but Mind, Idea, Soul, Spirit, Consciousness, etc. Matter does not exist (its an illusion?).
Application to the mind-body problemMetaphysical Materialism: A person is nothing but a physical organism (body only). "Mind" (consciousness) a feature (function, epiphenomenon) of the body.
Metaphysical Idealism: A person is consciousness only (mind, soul, spirit); not at all a material being.
Metaphysical Dualism: A person is a composite of (1) mind (consciousness, intellect, soul, spirit) and (2) body.
Cartesian Dualism I know with certainty THAT I exist (Cogito ergo sum), butWHAT am I?Am I my body? No, because I can doubt the existence of my body, whereas I cannot doubt the existence of myself (the I).I am a thinking thing, a thing that doubts, understands, affirms, denies, wills, refuses, imagines, and has sensations.
Is Descartes right?Can you doubt the existence of your body (as well as other physical things)?Why or why not?
I can conceive of myself as existing without a body, but I cannot conceive of myself as existing without conscious awareness.Bryan Magee, The Great Philosophers (Oxford 1987)
DetourDescartes' piece of wax(What is this about?)D' piece of wax is a physical object.How is it known? Through the senses? Through the power of imagination? Through the intellect (judgment, intuition)?
That piece of wax.A major dispute running through the entire history of philosophy has to do with the source(s) of human knowledge. There are two major schools: rationalism and empiricism. The empiricists hold that knowledge is derived from sense perception and experience. The rationalists (such as Descartes) hold that knowledge is derived from clear logical thinking, from the intellect (i.e., from "reason").
In the "wax" section, which is a kind of detour from his main argument, Descartes is showing his support of rationalism. He argues that we know - through the intellect - that the wax is and remains what it is as it passes through time and change. Sense perception does not show the "substance" of the wax but only its various appearances. If we relied on sense experience rather than on "reason," then we would "know" that the wax is all of the following: cold and hard, warm and soft, hot and liquid. However, "reason" (not the senses) tells us that the substance (reality) of the wax is something more fundamental than its sensual appearances.
Soin Descartes view,my body exists (if it exists at all) outside of my consciousness and is therefore part of the external world.Thus,Back to the mind-body problem.
Descartes mind-body dualism leads to . . . .
Meditation III,which deals with(1) skepticism concerning the existence & nature of the external world&(2) the existence of God
I must, as soon as possible, try to determine (1) whether or not God exists and (2) whether or not He can be a deceiver. Until I know these two things, I will never be certain of anything else (Text, 289).Why does Descartes say this?
And why does Descartes think it necessary to prove the existence of God?It's because he's looking for a guarantee that the "external world" (the world outside of his mind) is really real and not just an illusion. How does a proof of the existence of God help him with that problem?The point is that God (who is no deceiver) guarantees that the world I perceive through my senses is really there. God authenticates my sensory experiences, thus making sensation generally reliable, not in and of itself, but because God (being perfectly good) will not allow me to be systematically deluded and deceived.By the way, if Descartes trusted his senses, this "external world" issue would not be a problem for him. But Descartes, a "Rationalist" rather than an "Empiricist," does not trust sense experience. He needs something more than sense experience to convince him that the "external world" is real. He needs God.
Descartes standard of certaintyWhat does it take for a belief to be certainly (indubitably) true?The belief must be clear and distinct. (But what does this mean?)Descartes general rule: Everything that I can clearly and distinctly grasp is true.
Are the following beliefsclear & distinct(indubitable)?That there are things outside myself (such as physical objects).That these external things cause my ideas of those things in my mind.That my ideas of external things perfectly resemble the things themselves.That 3 + 2 = 5 ?
Reasons for believing (1) that there are things outside myself, (2) that these external things cause my ideas of those things in my mind, and (3) that my ideas of external things resemble (accurately represent) the things themselves*:
*The epistemology represented by (1), (2), & (3) is known as Representationalism.
I have a strong natural inclination to believe the preceding three propositions.
My ideas of external things arise in my mind independently of my will.
It seems obvious that external objects impress their own likenesses upon my senses.(Do these reasons clearly & distinctly prove that Representational Realism is true?) (See 289-90)
Ideas & their causes
When I think of an entity, I can distinguish between . . . .Substance (i.e., the entity itself, e.g., an automobile tire),Modes (i.e., the ways in which the entity exists, e.g., the tire may be flat ), and Accidents (i.e., the properties, qualities, or attributes of the entity, e.g., the color of the tire [blackness?] ).And isnt it obvious that substance is more real than mode or accident?
Ideas of things (substances, modes, accidents)must be caused to be in the mind, andthe cause of any effect must be sufficient to produce its effect, i.e., there must be at least as much reality in a cause as is represented in its effect.
Descartes thinks of ideas assubjective representations of the realities that cause them to be in the mind.He also believes that ideas cannot represent more reality (anything greater or more perfect) than is in the things the ideas represent.But is this last point true? Suppose I perceive an automobile with a dented fender &, from my perception, an idea of the car arises in my mind. Why cant I think of the car as NOT having a dented fender?How might Descartes respond to this criticism?
If one of my ideashas something in it that is not within myself, thenI could not be the cause of that idea; whereasif I could be the cause of all of my ideas, thenI will have no foolproof reason to believe that anything exists other than myself.
Ideas in my mind:of myself (could be caused by myself)of Godof lifeless physical objectsof angelsof animalsof other peopleCould be composed from my ideas of myself, physical objects, and God (how?)What about physical objects?
The qualities of physical objects:Primary qualities: size, length, breadth, depth, shape, position, motion, substance, duration, number, etc.Secondary qualities: light, color, sound, odor, taste, heat, cold, etc.
Since my ideas of the secondary qualities of physical objectsare not clear and distinct,and since such qualities are almost indistinguishable from nothing (i.e, they seem to represent very little reality),I myself [a substance] could be the author of such ideas.
I could also be the cause of my ideas of primary qualities.I am a substance.I have duration in that I exist now and have existed for some time.I can count my several thoughts and thus the idea of number may be grounded in my thought process.But what about my ideas of extension, shape, position, and motion?
Although extension, shape, position, or motion do not exist in me (since I am not a physical being), these are only modes of existence, and, as a substance, I have more reality than these modes and I am therefore sufficient to cause my ideas of them.
Thus,I could be the cause of my ideas of both the primary and secondary qualitiesof physical objects.However,
I do not have what it takesto produce the idea of God (an infinite substance)from within myself (a finite substance).
Descartes first argumentfor the existence of God . . . .
By God, I meanan infinite and independent SUBSTANCE, all-knowing and all-powerful, who created me and everything else . . . . (Text, 291)This idea represents more reality than there is in myself (since I am finite, limited in knowledge & power, etc.). Thus, the idea of God must be caused to be in my mind by something other than myself. And . . . .
since there must be at least as much reality in a cause as there is in its effect(s),it follows necessarily that my idea of God must be caused by God Himself; and if God is the cause of my idea of God, thenGod must exist!
Descartes main point here isthat I could not be the cause of the idea of God that I find in my mindsince God is a being more perfect than myself.How could I, merely from within myself, form the idea of a being more perfect than myself?In that case, my idea would represent more reality than there is in its cause.Only God is a sufficient cause of the idea of God in my mind.
"Step 3" Presentation of D's 1st Argument for the Existence of God(not sure about this)1. All events are caused.2. A cause must be sufficient to produce its effects.3. My idea of a perfect being is a mental event.4. Only a perfect being is a sufficient cause of my idea of a Perfect being.5. If a perfect being is the cause of my idea of a perfect being, then a perfect being exists.----------------------------------------------------------------------------6. A perfect being (God) exists.
Descartes second argument
for the existence of God . . . .
I exist as a thinking thingwith the idea of God (an infinitely perfect being) in my mind,but my existence is not necessary -- it is contingent (i.e., my non-existence is conceivable, logically possible) -- which meansthat I must be caused to exist (at every moment of my existence) by something other than myself (292-3).
If the cause of my existenceis itself a contingent being or a set of contingent beings (e.g., my parents or something else less perfect than God), thenit must also be caused to exist by something other than itself. But . . . .this cause-and-effect process cannot go on to infinity since in that caseI could never begin to exist (the infinite regress problem again).So . . . .
there must be a First Causewhose existence is necessary (rather than contingent).Furthermore . . . ,
this necessarily existing First Cause,which is the ultimate cause of my existence,must have the idea of God in it, andsince it is a First Cause, its idea of God must be caused by itself and nothing else, which meansthat this First Cause must be God (since only God can be the original cause of the idea of God in any mind).
"Step 3" Presentation of D's 2d Argument for the Existence of God(not sure about this)1. All contingent beings must be caused to exist.2. I exist as a contingent and thinking being, with the idea of a perfect being in my mind [and as contingent, I must be caused to exist--premise 1].3. If something causes existence only if it is itself caused to exist, then its causal series is infinitely long.4. An infinite (or infinitely regressing) series of causes leading up to my present existence is logically impossible, since, in that case, I could never begin to exist [i.e., I would have no existence at all].5. A cause must be sufficient to produce its effects.6. To be a sufficient cause of my existence, the "first cause" of my existence must be a necessarily existing [premises 4 and 5] and thinking being possessing the idea of perfection [premise 2].7. The "first cause" of my existence is the cause of its own idea of perfection and is therefore, itself, a perfect being [otherwise it would not be "first"].----------------------------------------------------------------------------------------------------------8. A perfect being (God) exists.
Why does Descartes reject the claim thathis existence as a contingent being with the idea of God in its mind might be the effect of several natural causes, each representing a different kind of perfection? (see 293)
Conclusion of the 3rd Meditation
"From the simple fact that I exist and that I have in my mind the idea of a supremely perfect being, that is, God, it necessarily follows that God exists . . . . The whole argument rests on my realization that it would be impossible for me to exist as I do -- namely, with the idea of God in my mind -- if God didnt exist. It also follows that [since God is perfect] God cannot be a deceiver [because fraud and deception are caused by defects] . . . ."
The idea that God cannot be a deceiver leads toSlides on Meditation IV under construction but see next slide for a brief summary.
The Basic Thrust of Meditation IV:If God is no deceiver, how is human error with respect to truth and falsity possible, and how is that error to be explained?Human nature is equipped with an intellect (faculty of knowing) and a free will (faculty of choosing), which interact in the pursuit of truth. The intellect is capable of forming beliefs that can't be doubted and therefore are certainly true. However, the intellect can also consider claims that are subject to doubt and that therefore may be false. The human will is free to affirm or deny propositions proposed to it by the intellect. Error results when the will (1) denies the truth, or (2) affirms claims that are false, or (3) asserts knowledge where there is doubt.Error is avoidable where a person limits her his affirmations and denials to "those matters that are clearly and distinctly [indubitably] shown to . . . [the will] by the intellect . . . . " and remains (more or less) neutral with respect to all claims that are subject to doubt.Why does God permit human error? If human nature were created both free and incapable of error, it would be more perfect than it now is; but it may be that the apparent imperfection of human nature in this respect is necessary to "a greater perfection of the universe as a whole."
God & the removal of doubt as tothe existence of the external world
The content of Meditation VMathematical thinking & its (physical & non-physical) objects: clarity & distinctness again -- what is clear & distinct must be true
Ds ontological argument for the existence of God
God & certainty
Descartes third argumentfor the existence of God(the ontological argument again)
1. If the nonexistence of God (an infinitely perfect being) were possible, then existence would not be part of Gods essence (that is, existence would not be a property of the divine nature).2. If existence were not part of Gods essence (that is, a property of the divine nature), then God would be a contingent (rather than necessary) being.3. The idea of God as a contingent being (that is, the idea of an infinitely perfect being with contingent rather than necessary existence) is self-contradictory.4. It is impossible to think of God as not existing.
5. The nonexistence of God is impossible.
Certainty about Godis the basis of certainty about everything else.
Meditation VIRemoval of doubt as to the existence of the external worldSince God exists& is no deceiver,it follows necessarilythat the external world can be known to exist.
To be continued.(There's a lot more in the 6th Meditation than is covered in this presentationso far.)