(The views in this article are those of Descartes and should not be misconstrued as those of the author.)
Because Descartes has a good reason why he cannot write another defense of his argument, I have assumed his mantle. The skeptics have given Descartes quite a whacking, and I aim to explain and defend Descartes’ arguments. The skeptics claim that there is no way to establish with certainty a correspondence between idea and its object. Beating them on their own turf, I will demonstrate how Descartes proves that one can know something, know something outside the self, and know the physical world.
Four skeptical arguments particularly bring into question the indubitably of my most basic beliefs. First, that my senses may be deceiving me. Secondly, I may be dreaming and do not know it. Thirdly, I may be insane. Fourthly and most dastardly, an evil god may be systematically deceiving me. The last of these, if true, would mean that I could not know that two plus three equaled five because the god could have caused me to think that instead of realizing that two plus three actually equal fish.
The god being the worst of my problems, I should demonstrate first of which an evil god could not deceive me. I can doubt my house exists. I can doubt god exists. I can even doubt I exist, but in every act of doubt there is an actor. It is immediately evident that doubting is occurring. Doubting clearly and distinctly entails that the doubter (or I) exist. For precedence of such an argument, the reasoning here is much like Socrates defense against the accusation of atheism. Since it is claimed that Socrates believes in supernatural activities, this entails that Socrates must also believe in supernatural actors, for every action has an actor. In other words, he cannot be an atheist. Likewise, for every instance of doubt there must be a doubter. I cannot rationally doubt my existence without contradiction. Having proven that something is true, I now have reached my Archimedes’ point and may start my ascent back into the world of fine college dining.
I know at this point that I am a thing which “doubts, understands, [conceives], affirms, denies, wills, refuses, which also imagines and feels” (94). I also know that something cannot come from nothing, for that is inconceivable. There are also ideas that I have which clearly do not come from my being, for these ideas present something of greater formal reality than I. Since every cause must have a greater or equal formal reality, the idea of an absolutely perfect being with infinite formal reality must have a cause outside of my being. The only entity capable of having creating such an idea is this perfect being, for any lesser one would have to receive it from something still greater.
Assuming correspondence, Big Bang theorists, Evolutionists, and mothers may claim that things start off at humbler origins, thus contradicting the principle of greater-or-equal-to causation. I know this principle a priori. The principle is demonstrated by the fact that it is impossible to get ten coins from a set that contains only five but possible to take up to ten from a set containing ten. This is basic mathematics. Having this principle in mind, the universe, the evolution of species, and my maturation are explained by the guiding hand of a higher being.
This higher being is “eternal, infinite, [immutable], omniscient and a Creator of all beings outside of itself” (99). The deity is not lacking in any way, which means it could not deceive me. In order to deceive, one must have some kind of lack. For instance, I might lie because I find telling the truth embarrassing, self-incriminating, or generally displeasing. Since having a fault would contradict its being infinite, the deity must not be deceptive. Since the deity is not deceptive, it must have given me—its creation—the capacity to determine correspondence.
If I have the capacity for determining truth, why do I err? Though I cannot know why the deity created me, I can know that I have all the tools necessary to defeat the skeptics’ arguments. I know that part of my nature allows me to affirm and deny things and another distinct part allows me to know something clearly and distinctly. The former I call the will. It allows me to doubt my existence even though I know that I must exist. The latter is my understanding, the tool which god has given me.
To say I know something is to say I understand it clearly and distinctly. It is important to distinguish this from imagination, for while I may understand what a thousand-sided polygon is, I cannot imagine it. The same goes for god. To understand something is to know its essence. The res cogitans must have the capacity to think and god must exist, for those are their essences. No sooner do I remove those qualities then do I eliminate them. If god does not exist, for instance, he would be limited; thus, he would not be the infinite god.
Now that I know that an evil god is impossible, I can tackle the skeptic’s other arguments. I cannot be insane, for I already established that I can have clear and distinct ideas, while an insane person by definition could not think properly. If cannot be dreaming, for I can tell if I am in a waking state or a dreaming state. For example, while things within a dream are nonsensical, the real world is consistently logical. I can know that my senses are not deceiving me because god would not give me my senses in order to deceive me. If I happen to see a mirage, it is not the failure of my sense but of my will.
I know that god cements my connection with formal reality. Knowing that, I can start to explore the world outside of my mind. First, I establish that the essence of objects in the world is that they are extended. Second, I can derive from their dimensions a formal language which conveys knowledge about those extended objects to others. Thirdly, that language is mathematics. From my personal experience through the understanding, I derive corresponding conceptions for the res extensa.
The relationship between mind and body is interactive. While there are impulses originating in the body, there are intentional actions from the brain. The god, being so kind, has provided me with bodily warnings so I may maintain my body. A hunger to tell me to eat in order to maintain the material conditions of my body. Some may point out that when I have a foul itch, I look for anything that will scratch. They misunderstand what an itch is. The god would never create me with such a flaw. It must exist for my benefit; I just have to determine how to act upon it. As I should never eat anything poisonous regardless of my hunger, I should be conscious of the best way to relieve my itch—preferably with a cream.
I have responded to skeptics’ arguments and demonstrate that knowledge is indeed possible about my being, god, and the world. I made god the bridge between my mind and the world. The existence of god is indubitable, for it is the source of all existence. The god has infinite formal reality, so my idea of god maps onto it. I have divided the universe into three substances: the mind, the physical, and god. These all have distinct qualities. A god and res cogitans cannot be a res extensa because the res extensa is divisible and the others are not. The god does not have limits on its understanding which I do. These substances interact in such a way that I have an idea of god, perceive the world, understand physical objects, and control my body within certain limitations. Now I have return back to my life in college.