ds descartes lecture

8/13/2019 DS Descartes Lecture

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DS PhilosophyDescartesMeditations

Raul Saucedo

January 15 2014


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Mini Bio

Born in central France to a family of lawyers in 1596early in the Enlightment and Scientific Revolution, almostthree centuries after Aquinas death and four decadesyounger than Spinoza, Lebniz, and Newton.

Studied at La Flche following the standard Jesuitcurriculum:

Greek, Latin, and classic literatureMath (Euclid)Physics and philosophy (Aristotle, scholasticism)


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Mini Bio

Major works: The World(1633), Geometry(1637),Discourse on Method (1637),Meditations (1641),Principles ofPhilosophy(1644), The Passions of the Soul(1644).

Died of pneumonia in1650 (age 54) while serving Queen

Christina of Sweden as a tutor.


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Short CV

Massive intellectual badass, jack of all trades:One of the greatest mathematiciansof all timeof the caliber

of Archimedes, Pythagoras, Fermat, Gauss, Newton, and Euler.

One of the greatest physicistsof all timeof the caliber ofAristotle, Galileo, and Newton.One of the greatest philosophersof all timeof the caliber ofPlato, Aristotle, Hume, and Kant.


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Not particularly humble about itShort CV


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Math

Developed an analyticapproach to geometry, bringingtogether algebraandgeometrytwo central but untilthen seemingly disconnected branches of math.

Heard of the Cartesian coordinate system? Linear andquadratic equations? Formulas for slope and distance? Yup, thats the D.


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Math

This was the first alternative to Euclids syntheticapproach ina span of ~2000 years. Has remained dominant since.

With the development of analysis in the 18th century, itprovided the basis for substantive new results not only ingeometry and math generally but also in physics.

Petty tiff with Fermat over this, a la Newton vs Leibniz overcalculus.


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Physics

Major contributions to optics, including the derivation ofthe sine law of refraction. (Also tiff with Fermat over this.)

Influential theory of planetary origin and motion.


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Physics

Most importantly: first distinctly modern system ofphysical laws, after which Newtons is explicitlymodeled.

General principles of motion (including the law ofinertia), in terms of which allphysical reality could beexplained.


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Physics

A bit more generally, hes one of the first theorists topropose a mechanisticalternative to Aristotelianteleological hylomorphismgenerally.

Recall: in the Aristotelian framework, bodies are

compounds of matterand form; in virtue of their forms,they are characterized and governed by distinctive ends.


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Physics

So different kinds of bodies are distinguished in terms oftheir matter and form.

Differences in their motions and changes are explained interms of corresponding ends.

So we have very different explanations for thecharacteristics and behaviors of different bodies.


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Physics

Not so according to the mechanistic approach.

There are no forms or endstheres only one kind ofmatter, with uniform quantifiable features throughout.

Different bodies are simply different arrangements of theonly matter there is.

Their motions and changes have a uniform explanationtheyre all governed by the same very same general laws.


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Philosophy

In fact, Descartes conceives of is task in theMeditationsasproviding the philosophical foundations for thismechanistic physics:

I may tell you, between ourselves, that these six Meditationscontain all the foundations of my Physics. But please do nottell people, for that might make it harder for supporters ofAristotle to approve them. I hope that readers will gradually

get used to my principles, and recognize their truth, beforethey notice that they destroy the principles of AristotleLetter to Mersenne, 1/28/1641


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Meditations

Accordingly, the main claims he aims to establish are:Both mental and material entities exist [2, 6]The essence of mental entities (i.e. minds) is mentality [2]The essence of material entities is extension [2]Mental and material entities are distinct and independent:mentality and extension dont constrain each other [6]Persons are mental entities (not mental-material compounds) [2]

Bodies are material entities (ditto) [2, 6]

Other claims and arguments are just as innovative butauxiliary to these conclusions.


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Doubt

Given the stakes, he wants to ground this body ofknowledge in an unshakeable foundationhis conclusionsmust rest on completely secure footing.

He thinks that in order to do that he must convince eventhe most radical skeptic.

In particular, he wants to find an indubitableArchimedeanpointa belief no skeptic could in principle call into

questionfrom which he can build up. He searches for such a point via the method of doubt,

posing increasingly radical skeptical scenarios.

Skeptical doubt as tool in search epistemic foundations.


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Doubt

The question is: is there a belief even the most radicalskeptic couldnt in principle doubt? A belief theres in principle no reason to call into

question? First, Descartes argues that no such belief could be

grounded in sense perception. Similarly with mostconceptual beliefs grounded solely in reason, e.g. math and

logic. All such beliefs could in principle be called intoquestion.

Second, he argues that theres one such beliefthe non-perceptual, non-conceptual belief that I am thinking.


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Doubt

Three stages of doubt undermining all perceptual andconceptual beliefs:1. Illusion: undermines all specific perceptual beliefs about the

world, but not the belief that theres such a world.

2. Dream/hallucination: undermines the belief theres anexternal world altogether and so all empirical beliefs, butnot purely conceptual beliefs about it.

Ifxis a triangle,xhas three sidesIf there are at least nthings, there are at least n-1things

3. Evil demon: undermines all beliefs of reason.


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Doubt

One might quibble about these skeptical scenarios. Butfor dialectical reasons, Descartes wants to granteverything to the skeptiche wants to beat her at herown game, and thinks he can.

Descartes claims that one belief survives all the aboveskeptical scenarios: the belief that I am thinking.

The idea: I couldnt in principle call into question that I amthinking, for in doing so I would be thinking.

Lax understanding of thinking: having a mental life ingeneral, encompassing being hungry, imagining, hoping, etc.


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Cogito

From this we get the infamous Cogito, an argumentpurportedly further establishing that at the vey least heexists:1. I think 2. If I think, I exist3. Therefore, I exist

Descartes thinks that (1) cant be called into question. Heseems to assume that so is (2), and that so the move from(1) and (2) to (3).

Is that right?


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Cogito

Lichtenberg (and many others after him) famously arguesthat (I) could be indeed called into question. Perhaps we cant doubt that there is thinking going on, but

from its a big leap from that to the claim that *I*am

thinking (or that anyoneis, for that matter).

Compare: that its requiring doesnt require that anythingbe raining. The skeptic might insist thought is like that.


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Cogito

Russell: I think is his ultimate premise. Here

the word I is really illegitimate; he ought to statehis ultimate premise in the form there arethoughts. He nowhere proves that thoughtsneed a thinker, nor is there reason to believe

this


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Cogito

Perhaps Descartes can respond that thought, unlike rain,requires an agent.

Maybe so. But good luck convincing the skeptic!

Consider:If theres thought, theres a thinker

Perhaps something like this is a conceptual truth. Butthose were undermined by the evil demon scenario The very same problem afflicts (2) and the inference from

(1) and (2) to (3).


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Cogito


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Cogito

It seems that either he needs to look for a differentstarting point for his project (Kant), get the existence of athinker in a different way (Kant), undermine the evildemon scenario (prove that god exists before attempting

to establish anything else), or grant he cant but needntbeat the skeptic (Spinoza, Leibniz).

In any case, notice that, according to Descartes, hisArchimedean point is not an empirical belief grounded in

sense perception. Rather, it is meant to be self evident bya simple intuition of the mind.

Hence Cartesian rationalismthe foundations ofknowledge are not the senses.


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Essence

Granting hes established that he exists, he goes on toinquire what he iswhats his essence or nature. Essence: that in virtue of which an entity is what it is. For

shortfeatures it couldnt exist without. He argues that he is a thinking thinga mental entity or

mind, whose essence or nature is to think. [He moreasserts this than give any arguments for it.]

He contrast this with the essence of bodies,should therebe any (since hes not yet entitled to any claims aboutthem), which is extensiontheir nature is to occupyspace.


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Essence

Wax argument:1. In all cases of in which a body changes, a single entity

persists through the loss or gain of properties.

2. In some such cases no qualitative properties are preserved.

3. In no cases extension fails to be preserved.


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Essence

Notably, Descartes insists that (1)-(3) are beliefsgrounded on reason alone, not experience. Even if so, howcome they survive the skeptical scenarios?

Moreover, is extension really privileged over, say, shape,mass, or even color or texture? Worse: from (1)-(3) it at best follows that there exist

material entities whose essence is extension, not thatbodies (rocks, trees, cats, etc) are such entities.

For all hes said, that material entities could simply becomponents of bodies qua mind-matter compounds.


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Essence

Note that at this point Descartes is not trying to arguethat minds are distinct from bodies. For all hes said upuntil now, mindsmental entities with thought as their

essencemay be embodied, and be also essentiallyextended.

Its simply that this all he can say at this point of theskeptical argumentthat thought is the nature of mind.

His case for dualism doesnt come until later in the 6thMeditation, after hes secured the existence the externalworld.


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Path to the External World

In between that Descartes goes to great lengths in tryingto establish the existence of the external world.He defends clarity and distinctnessthe mark of hisArchimedean pointas a general criterion for knowledge [3]For which he needs to rule out the evil demon scenario[3-4]For which he tries to prove (without appealing to clarity anddistinctnesshence the infamous Cartesian circle!) that god

exists and wouldnt let us be systematically deceived [3-4 ]but also let us err sometimes [5]On the basis of which we can generally trust our senses afterall, their imperfections notwithstanding [6]


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Dualism

Descartes offers two arguments for the distinctness ofmind and body.

The most influential onethe Conceivability Argument:1. I can clearly and distinctly conceive of a situation where I (a

mental entity) exist without a body2. If I can clearly and distinctly conceive a situation, that

situation is possible3. Thus, a situation where I exist without a body is possible

4. Hence, I am not a body


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Dualism

The conclusion follows from the premises given LeibnizsLaw, aka the Indiscernibility of Identicalsanuncontroversial truth of reason if there are any:

If aXhas a property that Ydoes not, thenXis not identicalto Y

For given the premises my mind has a property that nobody couldpossibly existing without a body.

So the action is in the premises.


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Dualism

Descartes supports the second premise by appeal to thenature of clarity and distinctness and the nature of Godshe doesnt deceive us about clear and distinctperceptions and could create any situation.

In support of the first premise, Descartes could appeal tothe process of doubt leading to the Cogito, where hepictured himself as existing even if there were no bodies.

But certainly not everything he pictured in process ofdoubt was clear and distinctfor he pictured things thatwere clear and distinct perceptions failing (e.g. math andlogic, that theres an external world), so those couldnt

have been clear and distinct perceptions themselves.


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Dualism

A tougher problem: Clark Kent and Superman areidenticaltheyre one entity (even it exhibits verydifferent behavior in different circumstances). So onecouldnt exist without the other.

Nonetheless, Lois believes that Clark Kent and Supermanare two distinct entities. Does she clearly conceive asituation where one exists without the other?

If so, the second premise failswe could clearly anddistinctly conceive an impossible situation. Otherwise, its unclear exactly what clarity and

distinctness are supposed to amount to


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Dualism

Princess Elizabeth raised a powerful objection not to theargument per se, but to Cartesian dualism generally.

Mind and body arguably causally interact.

One case: sense perceptiontheres an apple in front ofme, I see red.

Another case: actionI have an itch, I scratch; I scratch, itno longer itches.


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Dualism

Elizabeths interactionist objection:1. Only material entities can interact with bodies.2. Bodies interact with minds.

3. Thus, minds are material entities, contra Cartesiandualism.

Descartes wants to hold on to (2). So he responds bydenying (1) and trying to explain how mind-bodyinteractions are possible assuming Dualism.


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Dualism

He claims that such interactions happenvia the pineal gland.

But as Elizabeth points out, thats a terrible response: thepineal gland is a body. The question is precisely howbodies can interact with immaterial minds. Pointing to abody doesnt help!

Descartes admits he has nothing to add to his response(of course, not before saying that these are complexmatters that can confuse non-experts!)


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Summing up: Philosophy CV

As with his math and his physics: sets a new agenda formodern times and beyond.

Mechanistic alternative to Aristotelian metaphysics.

Modern formulation of the skeptical challenge and othercentral questions in epistemology.Modern formulation of the mind-body problem and

other central questions in the philosophy of mind. Great, massively influential big-picture ideas (less

impressive execution!)

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