Withholding assent from the "patently false" should be extended to "things which are not plainly certain and indubitable." ("Reason now persuades" him of this.)
He will attack principles "which supported everything" which he once believed.
The senses have sometimes deceived him, "and it is a mark of prudence never to trust wholly in those things which have once deceived us."
But deception seems confined to "very small and distant things." Who could doubt that his body exists? Madmen, but they should not be taken as the model.
My sleeping experiences are of "the very same things" as the waking experiences of madmen.
Although it seems that my present experiences confirm that I am awake, I have been deceived by similar thoughts in dreams, and on consideration of the cases "I see ... plainly that there are no definite signs to distinguish being awake from being asleep."
Suppose we are sleeping, and we have no bodies. But "the things seen in sleep" are such that they could only have been produced by something existing, perhaps "even more simple and uinversal" than bodily parts, "from which ... images of things are constructed."
If there is a God, who could be a party to deception in the same way as dreams, "how do I know that I am not deceived every time I add two and three or count the sides of a square or perform an even simpler operation, if that could be imagined?"
We are permitted to be deceived occasionally, so it is at least possible that I be created so that I am deceived all the time. If we came about due to a less perfect being, the possiblity of deception becomes greater.
A solution to the urge to believe what is highly probable: suspend judgment.
He supposes "an evil genius, as clever and deceitful as he is powerful, who has directed his entire effort to misleading me."
Thus he regards all external things "as nothing but the deceptive games of my dreams, with which [the genius] lays snares for my credulity."
Archimedean analogy. Why be so sanguine: "surely great things are to be hoped if I am lucky enough to find at least one thing that is certain and indubitable"?
The separation of mind from body begins:
I have persuaded myself of something even under the hypothesis that I have no body.
If I were to persuade myself of something, then I would exist.
So, I exist.
I am thinking that I am something.
Necessarily, at any time I think I am something, I am something.
Query: why can I not be deceived about the truth of the conditionals? As someone has said, the reasoning process as a whole is thrown into doubt and cannot be saved by reasoning. Thus the claim is made that I have an intuition of my own existence.
But what is the I which "necessarily exists"?
Rejection of Aristotelian solution: I am a rational animal.
A. Physical Description
C. Poorly-conceived soul: a subtle material between the coarser parts.
Some activities require a body:
There is an ambiguity here, however: the justification of my claims may not depend on a reference to my body, but the subject which makes the claim still might depend on the existence of a body.
I am a thing that thinks, and as such I am rational without being a rational animal. As a thinking thing, I am a thing which :
Aspects of the wax reached by means of the senses [and what happens to them when the wax is heated]
The same wax as perceived by the senses is perceived by the mind only. There is an analogy between sensory perception of the wax versus the use of thinking alone, and the appearance of a figuer in a coat. The mind alone judges whether it is a person or a robot. The issue is how we perceived "what the wax is" and "how it is known." An animal could perceive what we perceive by the senses (and presumably would not know what the wax is).
More reasons for my existence:
First, he enunciates a general principle connecting what is clearly and distinctly perceived with what is certain. What is clearly and distinctly perceived would have to be incapable of being false if it is to show us which of our ideas are certain.
"Yet this [clear and distinct perception of what I affirm] would hardly be sufficient to render me certain of the truth of a thing, if it could ever happen that something that I perceive so clearly and distinctly were false."
Next, he notes that his own existence is known through a clear and distinct perception, and it is certain. So he takes it that this self-knowledge should be taken as a model : whatever he perceives very clearly and very distinctly is true.
In the case of beliefs about sensible things ("the earth, the heavens, the stars, and all the other things that I perceived by means of my senses") he mistakenly thought (by virtue of habit) that he clearly perceived that
To remove the doubt, he should inquire:
Next Descartes considers truth and falsity.
Ideas are "like images of things"
Volitions and judgments are made by a subject + "something that is more than the mere likeness of a thing" Ideas considered in their own right are not false, nor does falsehood reside in the will or emotions themselves. Only judgments can be the source of error. The principal source of error is the assumption that ideas are "similar to, or in conformity with, certain things outside me."
Of ideas, some
The second category is paramount here. "Just what reason is there that moves me so that I believe that these ideas are similar to those arguments?"
The light of nature shows me "for example, that from the fact that I doubt, it follows that I am." It is the most trustworthy faculty, while natural impulse is unreliable.
And there may be a secret faculty in me that produces these ideas, e.g. what forms ideas in me when I sleep.
Nor does it follow that they are similar. The idea of the small sun derived from the senses differs from the computational idea (probably innate) of the large sun.
There is another path open to knowledge of external objects. This one goes through God.
All ideas "seem to proceed from me in the same way" and thus are equal. But they are different in what they represent.
Ideas of substances contain more objective reality than of modes or accidents. Idea of an infinite substance contains more than that of a finite substance.
Highest God = eternal, infinite, omniscient, omnipotent, creator of all other things.
The light of nature makes it evident that:
"At the very least there must be as much in the total efficient cause as there is in the effect of the same cause." This is a version of the "Principle of Sufficient Reason."
The formal reality of the efficient cause of an idea must be at least as great as the objective reality in its effect. "That this idea contains this or that objective reality rather than some other one results from the fact that the idea gets its objective reality from a cause in which there is at least as much formal reality as there is objective reality contained in the idea." The objective reality of the idea, though imperfect, is not nothing, and so "it cannot get its existence from nothing."
There is no infinite regress of ideas, so even if one idea can get its objective reality from another: "at length some first idea must be reached whose cause is a sort of archetype that formally contains all the reality that is in the idea only objectively."
By the Light of Reason I know that my ideas are like images which cannot contain anything better than their origins.
If I am not sufficiently perfect to be the cause of one of my ideas, then something else distinct from me must be.
I am only a finite substance, and I cannot attain to the infinite by negating the finite. I could not know that I am imperfect "if there were no idea in me of a more perfect being by comparison with which I might acknowledge my defects."
The idea of God is not materially false because it contains so much objective reality.
The idea of God is "the most true, the most clear, and the most distinct," "for, whatever I clearly and distinctly perceive that is real and true and that contains some perfection is wholly contained in that idea."
But maybe I am too hasty in denying of myself the needed perfections.
There is the question of my origin.
If I came from myself, I would give myself all the perfections (I don't have) and would be God.
I have not always been, because existence must be conserved.
It is obvious by the light of nature from the "nature of time" that "the same forece and action is needed to preserve anything at all during the individual moments as is needed to create that same thing anew--if it should happen not yet to exist." The distinction between creation and conservation is only a distinction of reason.
But I do not observe in myself any power to conserve myself. So I depend on some other being.
If the being on whom I depend is not God, then it too will be a thing that thinks and has an idea of God, and the argument repeats itself: either it is God or it depends on God.
Nor could a plurality of beings, each with some perfections, have conspired to produce me. I have the idea of the unity of these perfections, and this could not have come from a being in which they are not unified.
My parents do not preserve my being, nor did they produce me as a thing that thinks. They only "placed certain dispositions in the matter in which I judged that I- -that is, a mind that is all that I now accept for myself--am contained."
"Most evidently," God exists.
The idea of God did not come from the senses or from me, so it is innate in me "just as the idea of myself is innate in me." Like the sign of an artist, the idea of God in us is left as a kind of signature.
From all this it is obvious that God is not a deceiver, "for it is manifest by the light of nature that fraud and deception depend on some defect."