Recommended Reading

B. Williams (1978) Descartes, pp. 102-129, 278-304. Penguin Books.

Text of Descartes

Anscombe, E. and P. T. Geach (eds.) (1954) Descartes: Philosophical Writings London: Nelson’s University Paperbacks

Descartes

Born 1596, la-haye-Descartes. Minor noble family. Died 1650, Stockholm.

The Real Distinction Argument

The Argument from Clear and Distinct Ideas

Since I know that everything that I clearly and distinctly conceive can be produced by God just as I conceive it, it is enough that I can clearly and distinctly conceive one thing without another for me to be certain that the one is distinct or different from the other, since they can come into existence separately, at least by God’s omnipotence; and it makes no difference by what power this should come about, for one to considerthe things as different. Now, from the mere fact that I know for certain that I exist and that I cannot see anything else that belongs necessarily to my nature or esence except that I am a thinking thing, I rightly conclude that my essence consists in this alone, that I am a thinking thing, a substance whose whole nature or essence is to think. While it is possible (or rather, it is certain, as I shall show further on) that I have a body, which is very closely joined to me; nevertheless, since on the one hand I have a clear and distinct idea of myself, as purely a thing that thinks and is not extended, and, on the other hand, I have a distinct idea of the body as a thing that is extended and does not think, it is certain that this I, that is to say my soul, which makes me what I am, is entirely and truly distinct from my body, and can be or exist without it. (Med. 6, 114)

P1.       Whatever can be clearly and distinctly conceived apart can exist apart.

P2.       Whatever can exist apart are necessarily distinct from one another.

P3.       I can clearly and distinctly conceive my mind apart from my body.

P4.       Therefore, my mind can exist apart from my body.

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C.         Therefore, my mind is necessarily distinct from my body.

Commentary:

P1 relies upon the idea that whatever can be conceived apart can be separated by God. It is a way of talking about the possibility of separation even where there is no such actual separation. Note that this can’t be a part of the argument towards a real distinction until Descartes has proved that there is a God who is not a deceiver, because a malevolent demon could fool us into believing that we could make a conceptual distinction when we really couldn’t. (That’s why this ‘proof’ is in the 6^th meditation rather than the 2^nd. Incidentally, he uses the notion of clear and distinct ideas to prove God, giving rise to accusations of circularity – the Cartesian Circle.)

What is it to have a clear and distinct idea? Clarity has to do with being present to mind (only the mind is really clear in this sense) and distinctness has to do with having enough information in the idea to distinguish the thing from other things. To have a clear and distinct idea is to have a complete idea.

P2 is a consequence of the necessity of the non-separability of identical things. If two things are identical (‘morning star’ and ‘evening star’ for example) then one can’t exist without the other. If one can exist without the other then they must be distinct.

P3 is a conclusion that Descartes reached in Meditations 1 and 2. He reaches this conclusion by stages:

1.         He can’t be certain that bodies exist because the evidence for them is merely sensory, and the senses can be deceived. He may be mistaken, or hallucinating, or dreaming, or being deceived by a malevolent demon. (Med. 1)

2.         The same possibility of error does not exist for the claim that his mind exists. If he tries to doubt that he is thinking he realises that doubting is actually thinking, and so refutes itself. (Med. 2 pp. 68-71) So he can conclude ‘I think, I am.’ (aka ‘Cogito ergo sum’.)

3.         This only justifies thinking that I exist as a thinking thing; it does not justify thinking that I am only a thinking thing, or that mind and body are distinct. In order to show that they are distinct Descartes considers the essences of the two things.

a.         The arguments of the second meditation show that the essences of mind and body are different. The example of the wax (pp. 72 f.) shows that the nature of the body is not as presented to the senses. In fact our sensory ideas of the the wax are so variable and contrary that they could not possibly serve as the ideas of the nature of wax. (This is important, because if the essence of body were defined relative to the senses that could create a conceptual link between bodies and minds.) Descartes concludes that the esence of the wax is extension (occupying space) and is known not through the senses but through ‘a purely mental contemplation’ (inspectio)

b.         So much for the essence of Body. Moreover, Descartes has considered all his preconceived notions that mind might be some kind of body, and rejects them as inessential: they are not attributes he has if the Malevolent Demon is active. He concludes that the essence of Mind is thinking. (pp. 68-70).

4.         The conceptual independence of the ideas of the essences of mind and body guarantees their metaphysical distinctness. The fact that the idea of thinking does not entail the idea of extension or vice versa shows that the one cannot be a mode of the other.

P4 follows from P1 and P3.

C follows from P4 and P2.

Objections:

1.         To refute Descartes on his own terms you would need to show that he has not shown that he has a clear and distinct idea of the mind apart from the body.

            Descartes supposes that his concept of the mind as a thinking non-extended thing is complete. Here he is assuming that unless there is an internal relation between the concepts of mind and body – ie. unless the concept of body is a part of the definition of ‘mind’ – a complete concept of the mind is possible apart from that of the body.

But there might be necessary external relations between things that rules out having a complete concept of the one without the other. Eg. correlative terms like ‘parent’ and ‘child’ can’t be defined in terms of one another on pain of circularity, but neither can they be understood apart from each other.

Could something like that be true of the mind? Some philosophers argue that mind can’t be completely understood apart from behaviour – in particular, verbal behaviour – which involves the body. Others argue that thinking can’t be understood unless there is thinking about things in the world. If these philosophers are right then the concepts of mind and body are not conceptually distinct.

2.         Arnauld objects that excluding Body from my essence is just an intellectual abstraction. It doesn’t entail a metaphysical distinction between things. Compare thinking of something as being right angled triangle but doubting whether the square of its hypotenuse was the sum of he squares of the other two sides. I could know that A is F and doubt that A is G, and yet it could still be true that A is both F and G.

Descartes’s reply is that his doubt should be resistant to the most thorough considerations, which could not be the case in Arnauld’s or any other such examples.

3.         As Descartes presents the argument some have seen it as having the form:

            p1.        I can conceive of my mind as unextended.

            p2.        I can not conceive of my body as unextended.

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            c.         Therefore my body and my mind are distinct.

But this is an obviously fallacious argument. Compare it to this:

            p1.        I can conceive of the evening star as being different from Venus.

            p2.        I can not conceive of Venus as being different from Venus.

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            c.         Therefore the evening star and Venus are distinct.

On this interpretation he makes the mistake of substituting into ‘referentially opaque’ contexts, where co-referential terms are not substitutable salva veritate.

A non-fallacious interpretation of Descartes’s argument is possible (and it is the one that I have given already) in which the focus is on the essential attributes of the mind and the body which those objects necessarily have no matter how the objects are referenced.

The Argument from Divisibility

(Med. 6, p. 121)

P1.       The mind is indivisible.

P2.       The body is divisible.

P3.       If A is identical with B, then any property that A has will also be had by B.

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C.         Therefore, the mind is distinct from the body.

Commentary:

P1 is true for Descartes because he cannot conceive of any of the functions of the soul – sensation, understanding, willing – apart from each other.

P2 seems obvious, since the parts of the body can exist apart from each other.

P3 is a statement of Leibnitz’s law again. 

Objections:

1.         There are those who believe it makes very good sense to talk about the parts of a mind or even of divided minds.

2.         Certain cognitive functions depend upon the body, such as perception, memory.

3.         Descartes equivocates upon the word ‘division’ – ie. he admits that there’s a sense in which the body is indivisible after all – its parts cannot function apart from each other. (A leg cannot be a leg if it isn’t attached to anything for which it can perform the function of legging.)

Mind/Body Dualism

The idea that Mind and Body or the mind and the world are two quite different things is probably the most popular naïve theory of mind. This popular dualism probably envisages the mind as being like a less solid form of matter complete with extrension and colour and all sorts of other ‘material’ attributes. This imagines the soull as being a type of ‘ghost in the machine’, that drives the body like a man in a tank. The mind is located inside the body, usually in the head. The popular dualism also supports and is supported by the doctrines of various religions concerning the immortal soul. It is not surprising that the first philosophical theories of Mind, such as Plato’s, should have been much influenced by the popular view. Descartes version of dualism is just about the most sophisticated version of dualism attempted.

Substance Dualism

Descartes views the world as consisting of at least two types of thing, two substances, one of which is material and is essentially extended, and the other of which is mental and is essentially thinking. What is material does not think and what is mental is unextended.

Commentary:

Descartes describes how Mind and Body are related. Mind does not give life to the body as Plato sometimes seemed to think. The soul leaves the body at death, but death is not identical with the soul’s departure. The soul leaves because the body dies (Descartes Passionsof the Soul i 6, 5).

The soul does not dwell in the body like a pilot in a ship (Med. 6, 117), it must have a much closer relationship. Otherwise, though it might be able to direct the motions of the body, it would not be able to experience the things that affect the body. Sometimes Descartes says that the soul is ‘substantially united’ to the body, or ‘mixed up in it’, but no one is quite sure what this is supposed to mean. More often he says something to the effect that the soul is joined to all the parts of the body but more particularly to one part of the body where it exercises its powers (Passions of the Soul i 30-31); that is the brain, of course, but more particularly the pineal gland.

[What does it mean for an unextended entity to be ‘throughout’ an extended thing? It can have a position, but can it have more than one position at a time?]

The theory is that a subtle fluid – the animal spirit – flows through the nerves and is the medium of comunication between mind and body. The mind agitates the pineal gland, and this agitation is transmitted by the animal spirit to the limbs which are willed to move; and, conversely, the sense organs agitate the nerve fibres and the animal spirits convey that agitation to the pineal gland where the information may be accessed by the mind.

The pineal gland was chosen as the gateway by Descartes because it is the only part of the brain that is not duplicated, which he may have taken to reflect the unity of the mind.

Objections:

1.         The most common objection to substance dualism is that it is inconceivable that the two substances should be able to affect each other at all. So the mental would be unable to receive any sense information from the body and the body could not be moved by the mind. There could be no causal connection between the mental and the material.

Princess Elizabeth to Descartes (June 10, 1643):

I admit it would be easier for me to concede matter and extension to the soul than the capacity of moving a body and of being moved, to an immaterial being.

Descartes to Princess Elizabeth (June 28, 1643):

I beg [Your Highness] to feel free to attribute this matter and extension to the soul because that is simply to conceive of it as united to the body.

Descartes, in his reply to Elizabeth just cited (June 28, 1643), indicated that the difficulty that we have in conceiving of this connection is due to the educated person’s failure to recognise a primitive concept. He proposes that we should think not of two primitive notions – of soul and of body – but of three – those two and the union of soul and body. If we recognise this as a primitive notion then we can certainly conceive of the interaction between the two. Descartes, in an earlier letter to Elizabeth (May 21, 1643), had suggested that it was this primitive notion that was the pattern for our notion of the ability of heaviness to move a body towards the centre of the earth. We misapply the template of notions appropriate to the effect of bodies upon each other when we try to conceive the effects of mind and body upon each other.

Many found this answer to be unappealing. There were attempts to explain the connection between the histories of mental and material events.

a.                   Occasionalism. God steps in at every moment to ensure that a change in one is appropriately relected in a change in the other. (Malebranche)

b.                   Pre-established Harmony. Things are so ordered that the natural unfolding of mental events and the natural unfolding of material events – each according to their own causal laws – makes it seem as if they are really connected, but they’re not. Consider two clocks, one which indicates the time but does not chime the hour, and another which does not indicate the time but does sound its chimes at the correct time. (Guelincx and Leibniz)

c.                   Double-Aspect. Mind and Body are two aspects of a single substance that is neither mental nor material. The correlation of mental and physical events is due to their both being the result of a single cause acting in the real substrate and its effects manifesting themselves in distinct fashions in the mental and material aspects. (Spinoza)

2.                   There are objections to Dualism on the grounds of various conservation laws. Descartes was one of the first to propose such laws, in fact he had proposed a law of conservation of the quantity of motion that he claimed would govern his intersubstantial interactions. He did not elaborate on this.

3.                   Ockam’s Razor. [Entia non multiplicanda propter naecessitas] There is no increase in explanatory power provided by this new substance. It is just an ad hoc postulate. On the contrary the materialist is able to explain many cognitive deficits in terms of specific brain traumas, and the study of the growth, development, structure, operation of the brain has led to a knowledge of several mechanisms that are associated with really ‘mental’ functions, like learning, language, etc. Compare this with what the dualist can offer in the way of explanation. What can he tell us about the structure of the mind? What laws does it obey? How are pathologies to be explained?

4.                   Scientific Psychology speaks against dualism. If higher order cognitive functions like reasoning and consciousness are independent of the brain except for sensory input, then they could not be affected by anything that happens to the brain. But this is not the case.

Property Dualism

A different, less extreme, form of dualism is sometimes proposed in which there is only one –material – substance to be dealt with but where the brain has a special set of properties that no other physical object possesses. Properties like having pains, being in love, thinking that X, and so on.

These properties are not reducible to physical properties. They require a separate science of mentality to understand them.

There are various forms of property dualism:

a.                   Epiphenomenalism. The mental properties are properties that appear when the brain has a given complexity. They are characterised by the fact that there are no causal links from them down to the physical properties – causal links only go one way, upward. (Thus what I think or feel does not cause me to act in any way.)

b.                   Interactionist emergentism (my name) is just like epiphenomenalism except that while the mental properties are emergent properties they are also causally linked in both directionsto the lower level from which they have emerged.