Having established his method for identifying and discarding dubitable beliefs, Descartes now begins the process of finding out what, if anything, he can know. What follows is one of the most famous philosophical arguments.
The following is a slightly simplified version of the actual argument as it appears in Descartes’ Meditations:
‘I suppose, then, that all the things that I see are false; I persuade myself that nothing that I can remember has ever happened. I consider that I possess no senses; I imagine that body, figure, extension, movement and place are fictions of my mind. What, then, is true? Perhaps nothing except the fact that nothing in the world that is certain.
What about me? Am I not something?
But I have already denied that I had senses and body.
But am I so dependent on body and senses that I cannot exist without these?
But I was persuaded that there was nothing in all the world, that there was no heaven, no earth, that there were no minds, nor any bodies: was I not also persuaded that I did not exist?
Not at all; I persuaded myself of something, or at least I thought of something. - I am doubting.
But what about the evil demon? Isn’t this just another of his deceptions?
But if the evil demon is deceiving me, then he must be deceiving something – so I am not a nothing.
So that after having reflected well and carefully examined all things, we must come to the definite conclusion that this proposition: I am, I exist, is necessarily true each time that I pronounce it, or that I mentally conceive it.’
–Meditation IIEither I am being deceived, or I am not.
If I am not being deceived, then I exist
If I am being deceived then there must be something that exists that is being deceived – I exist.
If I doubt I exist, then there must be something that doubts: My doubting presupposes my existence
∴ The possibility that I exist, cannot be doubted
The cogito is known through intuition: It is direct and non-inferential knowledge – you do not infer your existence from something else, rather you just know it immediately without needing to argue for it; all you have to do is consider it and it becomes clear and distinct in your mind that it is true.
The cogito gives him a standard of truth/certainty – anything he can see as clearly and distinctly as this, he knows to be certain.
Some (like Hume and Lichtenberg) have argued that the conclusion does not follow from the premises: Descartes should have said: ‘thinking is occurring.’ The reference of the ‘I,’ is more than the cogito can justify. There may be nothing more than a continually changing array of thoughts and feelings. Yes, they may be similar, but not identical - i.e. we are confusing similarity with identity.
However, a Cartesian might respond that it's impossible to make sense of ‘thinking is occurring’ without there being a thinking thing.
However, could this thinking thing not be a succession of things rather than one persisting thing?
Bernard Williams made a further objection.
The difficulty is in being able to distinguish between an ‘I’ and anything else through pure consciousness. To say ‘I am thinking’ is something that is only true in the light of a 3rd-person perspective - something that Descartes does not have. (The concept of ‘I’ can only be understood in contrast to ‘not-I’ - a notion that Descartes doesn’t have at that point.)
Descartes then continues to demonstrate that his experience (or understanding) of the external world is very limited. He describes himself trying to establish what he can know of the wax-itself from his senses alone. His problem is this: all that is perceived of the wax are its various properties – its shape, colour, smell, - but as the wax melts, these properties appear to be continually changing; none of them appear to be essential. And so, what then can we learn about wax from observation if none of its properties are essential to it? The essence of wax remains unknown.
The essence of a substance is its unchanging properties.
All of the properties that I can sense are changing.
∴ The essence of a substance cannot be known through my senses.
Explain the Cogito argument in your own words.
Explain an objection to the cogito
What is your response to the cogito argument? Do you find it convincing? Does he prove that there is something?
Explain what Descartes thought about substance and essence
Do you agree with him about substance and essence?