Notes on Descartes
Descartes’ methodology is that he would doubt anything that had the possibility of being doubted. Doubting everything that has the possibility of being doubted would take forever, as you would have to go singular by singular, ad infinitum. Due to this, Descartes groups things and doubts them. For instance, he doubts his senses — as they can make mistakes. The senses also have another problem, that of which is the problem of dreams: how can you know whether you are in a dream or not?
As I think about this more carefully, I see plainly that there are never any sure signs by means of which being awake can be distinguished from being asleep.
After going through and doubting empirical senses, etc… Descartes states that at this point, with what we have doubted, the only things we have yet doubted are: colours existing (colour in its existence, not differentiation), all bodies having extension, and arithmetic/geometric truths (as arithmetic/geometric truths do not require sense-perception). Descartes here points out that there could be an omnipotent creature which tricks Descartes into thinking that colours exist, all bodies have extension, and that mathematics has truths. Thus, Descartes doubts them.
I will suppose therefore that not God, who is supremely good and the source of truth, but rather some malicious demon of the utmost power and cunning has employed all his energies in order to deceive me. I shall think that the sky, the air, the earth, colours, shapes, sounds and all external things are merely the delusions of dreams which he has devised to ensnare my judgement. I shall consider myself as not having hands or eyes, or flesh, or blood or senses, but as falsely believing that I have all these things. I shall stubbornly and firmly persists in this meditation; and, even if it is not in my power to know any truth, I shall at least do what is in my power, that is, resolutely guard against assenting to any falsehoods, so that the deceiver, however powerful and cunning he may be, will be unable to impose on me in the slightest degree.
Descartes realizes that all these thoughts must necessarily be derived from himself. There might be an omnipotent being deceiving Descartes, sure, but that still presupposes that it is deceiving him, it presupposes his very being; doubting presupposes his own existence.
I must finally conclude that this proposition, I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind.
If Descartes is to assert he is, then he must ask himself, who is he?
At last I have discovered it — thought; this alone is inseparable from me. I am, I exist — that is certain. But for how long? For as long as I am thinking. For it could be that were I totally to cease from thinking, I should totally cease to exist. At present I am not admitting anything except what is necessarily true. I am, then, in the strict sense only a thing that thinks; that is, I am a mind, or intelligence, or intellect, or reason — words whose meaning I have been ignorant of until now. But for all that I am a thing which is real and which truly exists. But what kind of a thing? As I have just said — a thinking thing.
If Descartes is to assert he is a thinking thing, then he must ask himself, what is thinking?
… even if, as I have supposed, none of the objects of imagination are real, the power of imagination is something which really exists and is part of my thinking. Lastly, it is also the same ‘I’ who has sensory perceptions, or is aware of bodily things as it were through the senses. For example, I am now seeing light, hearing a noise, feeling heat. But I am asleep, so all this is false. Yet I certainly seem to see, to hear, and to be warmed. This cannot be false; what is called ‘having a sensory perception’ is strictly just this, and in this restricted sense of the term it is simply thinking.
Descartes later uses what is called the wax example to affirm rationalism:
Let us begin by considering the commonest matters, those which we believe to be the most distinctly comprehended, to wit, the bodies which we touch and see; not indeed bodies in general, for these general ideas are usually a little more confused, but let us consider one body in particular. Let us take, for example, this piece of wax: it has been taken quite freshly from the hive, and it has not yet lost the sweetness of the honey which it contains; it still retains somewhat of the odour of the flowers from which it has been culled; its colour, its figure, its size are apparent; it is hard, cold, easily handled, and if you strike it with the finger, it will emit a sound. Finally all the things which are requisite to cause us distinctly to recognise a body, are met with in it. But notice that while I speak and approach the fire what remained of the taste is exhaled, the smell evaporates, the colour alters, the figure is destroyed, the size increases, it becomes liquid, it heats, scarcely can one handle it, and when one strikes it, no sound is emitted. Does the same wax remain after this change? We must confess that it remains; none would judge otherwise. What then did I know so distinctly in this piece of wax? It could certainly be nothing of all that the senses brought to my notice, since all these things which fall under taste, smell, sight, touch, and hearing, are found to be changed, and yet the same wax remains.
Perhaps it was what I now think, viz. that this wax was not that sweetness of honey, nor that agreeable scent of flowers, nor that particular whiteness, nor that figure, nor that sound, but simply a body which a little while before appeared to me as perceptible under these forms, and which is now perceptible under others. But what, precisely, is it that I imagine when I form such conceptions? Let us attentively consider this, and, abstracting from all that does not belong to the wax, let us see what remains. Certainly nothing remains excepting a certain extended thing which is flexible and movable.
Following up with,
These properties are however not directly perceived through the senses or imagination (the wax can be extended and moved in more ways than can be imagined). Instead to grasp the essence of the wax, it must be done through pure reason: We must then grant that I could not even understand through the imagination what this piece of wax is, and that it is my mind alone which perceives it.
Now that Descartes has proven himself (i.e. a thinking thing) to exist, he now attempts to expand out to proving Gods existence.
Descartes’ cosmological argument can be formulated as such:
P1: I have the idea of a most perfect (infinite, eternal, omnipotent, benevolent) being (God).
P2: A cause must be at least as great (real) as its effect.
Conclusion: This idea of God can’t come from (imperfect) me. Its cause must be God (or, impossibly, greater). God exists. (Link to where I got this syllogism from)