ways be compelled to remain in doubt whether God could not be "veracious and not veracious," "deceiving and not deceiving," unless the principle of contradiction were taken as granted before he begins to prove God's existence. Unwittingly Descartes does accept this principle of contradiction throughout his demonstrations, but that is an inexcusable inconsistency.So, too, Descartes conducts his inquiry under the supposition that he has doubted the principle of sufficient and the principle of causality. But he does not hesitate to use these principles before he has established their validity. Consider his a posteriori argument for the existence and infinite perfection of God.He contends that the idea of God as an all-perfect Being could not have originated in our mind, because such an idea would exceed the causality of the human mind, the latter being less perfect than the contents of the idea itself; consequently, this idea had to be produced in us by God Himself (and this proves that God exists as an infinitely perfect Being), otherwise there would be no sufficient reason for the presence of such an idea in our mind.This line of reasoning shows plainly that Descartes uses the principles of sufficient reason and causality in demonstrating God's existence, although he doubts their validity.Now, if he lets these principles stand as doubtful, his entire demonstration is vitiated and nullified by doubt; and if he accepts them as valid prior to establishing their validity, he acts contrary to his fundamental doubt and is inconsistent: in either case he makes the demonstration of God's existence impossible.His actual procedure in all the arguments he makes is such, however, that he presupposes the validity of the laws of thought; and that is for him a glaring inconsistency, since his universal methodic doubt will not permit him to accept their validity before he has proved the existence and veracity of God.Finally, Descartes' universal methodi...
