In A Discourse of a Method, Descartes defines reason as “the faculty of right-judging and distinguishing truth from falsehood.” He goes on to reflect that all traditional learning he received from a college education did nothing more than to increase his confusion about what is true. This isn’t to say he spent his time partying and not paying attention, but rather after learning different subjects he realized much of it contradicted each other or had shortcomings in establishing certainty.
The problem with philosophy is that many philosophers throughout history disagree with each other and which philosopher is accepted as true changes over time, only to be overthrown later with the advent of some new philosopher, repeating the cycle ad infinitum. Math, a subject near and dear to Descartes’ heart, while providing certainty, tends to be too abstract on the whole to be useful in establishing practical truths about the everyday world. Logic, while a useful tool, has the weakness in that it cannot establish any new truth or discovery on its own, but merely confirms what is already known. Meanwhile, the study of history tends to lead people to become obsessed with the past and become a stranger to the unique problems of their own time. In response to these problems, he develops a four step method to correct his errors of knowledge:
1) doubt everything except what is so obviously true that a person cannot possibly deny it
2) break down the problem to its simplest forms and parts
3) answer the simplest parts first and follow a natural order so that propositions that have been determined to be certain can be employed to establish the next part (new certainties).
4) finally double check each part for any errors of thinking that might have been overlooked.
In his more mature work, Meditations on First Philosophy, Descartes explores this method further, hoping to “make a clean sweep . . . of all my opinions.” He espouses a viewpoint that can be described as a type of skepticism: “To this end I shall not have to show they are all false, which very likely I could never manage; but reason already convinces me that I must withhold assent no less carefully from what is not plainly certain and indubitable.” According to his reason, we should not only reject what is obviously false, but also to withhold agreement or belief when something cannot be shown to be true. However, he is not doing this for its own sake, but rather because he wants to discern what can be established as true.
Most of what he holds true he gained through his senses, but also recognizes that his senses have deceived him in the past, and “a wise man never entirely trusts those who have once cheated him.” So to test out this method, Descartes will start with an extreme form of skepticism.
Descartes decides to assume that there is an evil spirit who is supremely powerful and is trying to deceive him. All external objects (sky, earth, his physical body, etc.) are just illusions created by this evil spirit to trick Descartes. If we assume this extreme scenario is there anything we can possibly know to be true?
There is a temptation to fall into the miasma of extreme skepticism in which a possible answer to the question is that the only thing we can know for sure is that everything is uncertain. However, Descartes rebuts this point by identifying another possibility: we can know that we think, and have perceptions, and therefore that we must exist. This is often summarized as, “I think, therefore I am.”Now it may be true that the evil spirit is tricking our perceptions to perceive things that aren’t there or don’t exist in an external world; however, for deception of the sense to even be a possibility, we ourselves must exist and must be capable of having thoughts. This is prerequisite for deception to occur. It’s impossible to be deceived and have incorrect ideas about the external world if you you don’t exist or are incapable of thoughts that can process deceiving stimuli. So he can at least establish that he is a conscious being capable of having thoughts and perceptions.
After the first two meditations, Descartes recognizes there is still room for doubt. In the past, before this exercise in doubt, he accepted the common belief that if we have ideas of things, it must be the case that the ideas come from an external reality. However, he has not proven this to himself yet and there is still reason to doubt it. The best way to reject the possibility that his perceptions may be deceiving him about the existence of an external reality or that ideas in his mind have a correlation to an external world is to find a way to disprove that a hypothetical evil spirit could possibly be deceiving him and prove that a G-d exists. His first proof for G-d is a gargantuan task.
To begin he must explore the nature of ideas by creating a “classification of all [his] experiences.” He defines ideas as “picture of objects.” He notes that some ideas have additional properties. We don’t just have a mental picture of a concept or object, but we can react to them in our mind, such as be afraid of them, assert or deny them, wish they existed, etc. We have emotional reactions and judgments about those ideas.
Descartes then claims that considered on their own terms ideas cannot be false. This needs to be unpacked a little. If I imagine a mythical creature like a hydra, then it is true that such an idea exists at least within my mind. It might not exist in an external world, but the idea of a hydra exists. The existence of my mental picture of a hydra is no less real than the existence of my mental picture of a she-goat. So there is no point in questioning the existence of a mental picture. Next, he suggests that falsehood in our emotions shouldn’t bother us either since a person may desire evil or what does not exist, but it still remains true that this is a genuine desire. Instead Descartes will focus his attention on the additional properties of ideas that he calls, “judgments.” To believe that an idea may correspond to an external reality is a type of judgment that transcends the initial idea that exists in the mind.
He then goes on to recognize three possibilities for the origin of ideas: innate, external, or imagination (invented by himself). His primary concern is “ideas that [he] regard[s] as taken from external objects.” Two possible pieces of evidence Descartes uses to show that ideas might stem from the external world is Nature (which I assume he means something like common sense, which he calls impulse, along with habit or repetition of experience) and that many ideas appear independent of his will, such as the fact that he will get hot by sitting near a fire whether he wills it or not and get cold out in the snow even if he desires it otherwise, therefore these things cannot depend on his consciousness. However, Descartes accepts that at best these are weak arguments.
The next part of his argument can get very confusing as it relies heavily on difficult philosophical terms originating in Medieval Scholasticism. Descartes notes that one idea as it exists in his mind is just valid and true as any other idea. So his imaginary picture of a she-goat is no less real as a thought than his imaginary conception of hippogriff. By which he means he is capable of having an idea about these things and that they are ideas is true whether they actually exist in the real world or not. However, it is important to remember that ideas at least on the surface seem to represent things found in reality and when we recognize this fact then a difference can be found. Certain ideas manifest substances and therefore have a greater reality than ideas that merely represent states or accidents. Another way of looking at this is substances are essential characteristics that define a thing, while states or accidents are temporary or non-essential characteristics.
Suppose we have a rock, which contains substance, accidents, and different states as part of its existence in the world. Substance is an essential quality of an object or thing of which without that substance the thing wouldn’t be what it is. So all rocks, not just an individual rocks, must possess the substance of rockiness. If an object, such as a rock, doesn’t possess this substance then it is no longer a rock. However, a rock also has accidents and states as part of its existence and characteristics too. An accident might be the color of the rock, a quality which is not inherent in all rocks, but just this particular rock (i.e. some rocks might be red, some purple, some silver, etc.). A state is a non-permanent part of its existence that can change about an object, such as if I throw a rock and it is now flying through the air, but will soon return to the ground, which will then make the rock be in a different state. A state is only temporary, while an accident is a non-defining characteristic. Substances have more ‘formal’ reality than state and accidents. Infinite substances have more reality than finite ones since it has more substance (an infinite amount). Since a substance is the defining characteristic or quality of an object, then an infinite object would have more substance and therefore more reality since its substance by definition of being infinite means it can never cease to be and must have more of it.
“Now it is already clear by the light of nature that the complete efficient cause must contain at least as much as the effect of that cause. For where, pray, could the effect get its reality if not from the cause? And how could the cause supply it, without possessing it itself? So it follows both that something cannot be made by nothing, and that what is more perfect, or contains in itself a greater amount of reality, cannot be made by what is, or has, less.”
If something causes a stone to exist it must have been produced by something containing all that is inherent in the stone and the thing that caused it must have more of the substance that makes and defines the stone. Something cannot be derived from nothing. We cannot have something superior or that possesses a greater amount of reality (or greater amount of substance) from something with less. He then takes this observation to note that even the idea of an object, such as the idea of heat, cannot be put into himself by “a cause in which there is in fact as much reality as I conceive to exist in the heat or stone.” In other words, even the idea of a stone must be caused by something that has more substance, and therefore reality, than the idea in order to produce the idea. No idea can come from nothing since an idea is something and he has proposed that something cannot come from nothing. One idea can cause another, but an infinite regress is impossible, and therefore there must be a first cause for all ideas. He tells us to “suppose some one of my ideas has so high a degree of representative reality that I am sure the perfection so represented does not inhere in myself . . . that therefore I myself cannot be the cause of that idea.” Using the arguments he has already developed he notices that if he has an idea of perfection it cannot have come from him since he is not a perfect being and therefore cannot be its cause or origin. If no such idea can be found in him, then he won’t have an argument to prove the existence of something other than himself.
He explores various ideas that he possesses: G-d, inanimate corporeal objects, angels, animals, and other men. Ideas like angels and men and animals could come from himself, even if there weren’t really angels, animals, and other men in the world. He notes that the reason he has an idea of substance is because he himself is a substance, but he could have no idea of an infinite substance because he is finite (so something with less cannot create something with more, even in our ideas). So the idea of the infinite must itself stem from something that is infinite. He argues it would be impossible from him to recognize his own imperfection—his doubting and desire—without the idea of a more perfect being as a standard to recognize his own defects.
“From the mere fact that I exist, and have in me some idea of a most perfect being, that is, G-d, it is clearly demonstrated that G-d also exists.”
The idea of G-d cannot derive from the sense, and “it is not my own invention, for I can neither add anything to it nor subtract anything from it. So it can only be innate in me, just as the idea of myself is. . . “And certainly it is not surprising that G-d, when he created me, should have implanted this idea in me, to be as it were an artist’s mark impressed on his work.” So Descartes argument for G-d’s existence looks something like this:
Premise 1: If I have a conception a perfect being as an imperfect one, then a perfect being must exist to give me that conception.
Premise 2: I have a conception of a perfect being as an imperfect one.
Therefore: A perfect being must exist.
Some might wonder how Descartes justifies his premises. All the proceeding argument that I outlined earlier serves as a justification for this line of reasoning. An imperfect being isn’t capable of conceiving a perfect being because finite must proceed from infinite due to more substance and reality, etc. The basic argument, however, is fairly simple once all that groundwork is laid down. Is this really a convincing line of reasoning? I’ll let others decide for themselves.
He offers a second proof for the existence of G-d in the Fifth Meditation. From his inability to think of G-d as non-existent, he suggests that existence is inseparable from G-d, and therefore G-d really does exist.
He opens this chapter by reasoning that even if a triangle doesn’t correspond to anything in the external world, nevertheless, he can conceive genuine mathematical truths and properties of the triangle that he can conceive and even prove. Due to the fact that he has the idea of G-d and he cannot conceive of G-d (a supreme perfect being) who lacks existence anymore than a hill without a valley, suggesting that existence is an integral characteristic of a supreme perfect being, therefore he can defend and support premise the idea that it is impossible for him to conceive of the idea of G-d with the characteristic of non-existence.
Anyway, this allows Descartes to make some further assumptions to get him out of the quagmire of his own doubts. Since G-d is a perfect being it is obvious that he would never be deceitful and try to trick our senses since this would be a defect and a defect would make Him imperfect. Likewise, since G-d is a benevolent and all-powerful being He would never allow an evil spirit to take hold of our senses. So our senses can be trusted to inform us that an external world exists. However, we clearly still make errors in our understanding. So this is the next problem Descartes must address. Did G-d put a flawed faculty of reasoning inside of us?
Descartes holds that a perfect being, by which he means benevolent, omnipotent, omniscient, etc. would not give us a flawed system of understanding. Instead he says, “I happen to go wrong because the faculty of right judgment that He has given me does not exist in me in an infinite degree.” He seems to be saying that reason can never wrong in itself, but rather that we have a limited amount so there are things beyond our understanding, but if we just had a little bit more of reason we would then understand it. Our ability to reason is fine and unflawed. Then he suggests G-d has designed us with two capacities: intellect (or reason) and free will. He sees our errors arising from the tension between the two. “Whence then do my errors originate? Surely, just from this: my will extends more widely than my understanding, and yet I do not restrain it within the same bounds, but apply it to what I do not understand.” This argument suggests there are things in the universe that the human intellect was not meant to know. When we apply our reason to things beyond our understanding because our free will makes us want to understand them then we will end up in error. This has resonance with the ancient world: gnothi seauton (know thyself), which isn’t meant in the self-help way of getting to know your innermost desires and feelings, but rather really means know your limitations. For this reason one might be tempted to read this as an anti-science, keep in your place, type of statement. So what would Descartes have made of all the modern scientific discoveries that would’ve seemed impossible or beyond our reason? Well, I suspect he would’ve adopted the argument to them; if we were able to learn about evolution or the Big Bang with our reason, or the products of our reason (the technological equipment needed to make some of those discoveries), then it wasn’t beyond our capacity to understand it in the first place. So he concludes the source of our errors stem not from our understanding, but from our own will, specifically our free will, when it goes beyond the limits of our understanding.
The final chapter (meditation 6) outlines the so-called mind-body problem. Descartes concludes that “it is certain that I am really distinct from my body, and could exist without it.” He believes that he is a being that primarily consciousness that interacts with a physical body, but otherwise the two are separate substances. By suggesting that the mind is separate from the body, this means it doesn’t have its origin in the physical brain. Neuroscience has essentially disproven this philosophical speculation and it really isn’t all that interesting to me as a philosophical issue.