The Wax Example

Descartes argues that he is a res cogitans, a thinking thing. He is a thing that "doubts, perceives, affirms, denies, wills, does not will, that imagines also, and which feels". Some of these attributes seem to link mental states to physical states, for example to our sense organs. Surely, to perceive something is to experience it through our senses? But Descartes insists that the essential features of perception are intellectual rather than sensual.

One purpose of the wax example is to demonstrate this point. Wax makes an excellent example because it connects with all the senses.

The wax has a certain colour, smell, taste. It is hard to the touch and makes a sound when tapped. But when it melts all these sensory properties change. The appearance, smell, taste, sound, and texture all change - and yet, Descartes says, he perceives it to be the same wax. This shows that the wax is not its sensory properties, for if it were its colour, taste, smell, etc. could not change without it being different wax. So when he thinks of the wax he is thinking of something that is extended (takes up space) and changeable.

It is not through imagination that he knows what it is, for he knows that it can go through more changes than he can imagine. If it's not through the senses, nor through imagination, that he perceives the wax, how does he do it? The answer is: through his understanding - ie intellectually. When he says he "sees" the wax (visually), what he is really doing is making an intellectual judgement.

He backs this up with the example of looking out of his window and seeing a man in the street below. What he actually sees from above is a hat and cloak moving along. But he makes a judgement that there is a man underneath (rather than a machine). He does not see the man visually; he makes an intellectual judgement that it is a man.

Notice that these examples are about how we know things. Although the wax example is sometimes seen as reinforcing the cogito argument, and the distinction between mind and matter, it is mainly about how we know things about the physical world. It makes a point about the nature of matter too, of course. The wax is not essentially its sensory properties; it is essentially those properties that are perceived intellectually.

This is not such an extraordinary idea - after all, nowadays we don't think that physical objects are really as we perceive then with our senses; we don't see protons and electrons, do we? But, on the other hand, we don't generally think of our recognition of objects as being an intellectual activity: we tend to think that we just see things, hear things, touch things, etc - in other words, that we know things through our senses. But surely Descartes is right. When we see things as something - eg a black shape as a cat - that is surely at least partly an intellectual judgement. Cats, of course, don't normally change all their sensory properties as we look at them, as the wax does. That's why the wax example is so well chosen, and why we wouldn't normally accept what Descartes says about true perception" (by which he means something close to recognition or identification) is an intellectual judgement. But if it true in the case of wax, it is perhaps true in the case of all perception. We intellectually judge or infer the presence of physical objects from their sensory properties, but the only physical properties we can judge objects really to have are extension and changeability.

So the first purpose of the wax example is to make a point about how we have knowledge of physical objects. The second purpose is to say something about what the essential properties of physical objects are.

Clear and Distinct Ideas. The Cartesian Circle.

Descartes is a rationalist. The cogito argument rests on an acceptance of an idea that is immediately present to his mind - not on experience or deduction (although this could be disputed). The thought that if he is thinking then he must exist is the first "clear and distinct idea". He intuits it directly, by pure thought. By "clear" Descartes means that the idea is open and present to the attending mind. By "distinct" he means that it is a precise, separated, sharply defined idea, not mixed up with other ideas or concepts.

The point is that at the time we rationally "perceive" the idea, its truth cannot be doubted. It is self-evident.

But what about when we are not attending to the idea, when we are not "perceiving" it directly? Does it cease to be true? What could make it true when we aren't thinking about it? Does its truth come and go?

One obvious response would be to say that memory makes it true. We remember that it is an idea we have previously perceived to be self-evidently true. But memories themselves can be confused, vague and inaccurate; and they are not demon-proof. So far there is only one demon-proof idea, for even if the demon is tricking Descartes about every other idea (and every memory), he cannot be tricking him about his existence.

So Descartes needs something other than memory that can establish enduring truths, truths that remain certain even when not be directly attended to. But having established that clear and distinct ideas are self-evidently true in the case of the cogito, he can now use them to establish the existence of God. Once he has established the existence of an omnibenevolent God he can be sure that God would not permit him to be systematically deceived. Some of his sense perceptions may be illusions, but his clear and distinct ideas, which are purely intellectual and not linked to the body, can surely be trusted. This means he can trust them to be true enduringly, even when not attended to.

The Cartesian Circle

This is a famous objection to Descartes' use of clear and distinct ideas. It is claimed that he argues in a circle, as follows:

1) I am certain that God exists because I am certain of whatever I clearly and distinctly perceive.
2) I am certain of what I clearly and distinctly perceive because I am certain God exists.

This would obviously be an unacceptable form of argument. But Descartes denied that he was arguing circularly. He said we can trust clear and distinct ideas without relying on God, but only at the time of the "perception". Once we have proved the existence of God (who by definition must endure when we are not perceiving his existence by pure thought), we can claim that we have enduring knowledge of him and his goodness, and that therefore we can trust our clear and distinct ideas not to be only temporarily true. Once we have proved even fleetingly the existence of God, we can be sure that we are not being systematically deceived by the demon - and therefore that what we clearly and distinctly perceive to be true is true enduringly, even when we are not attending directly to the idea.

Not everyone is satisfied by this response. You must decide whether you think Descartes'clear and distinct ideas theory, on which his whole philosophy depends, really does avoid the Cartesian Circle objection.