desy approached in one of two ways. First, it can be read as setting the ground for the meditations that follow, where doubt is employed as a powerful tool against Aristotelian philosophy. Second, it can, and often is, read standing on its own as the foundation of modern skepticism. We will briefly discuss these complementary readings in turn. Descartes saw his Meditations as providing the metaphysical foundation of his new physics. He wanted to reverse thousands of years of prejudices introduced into the Western tradition by Aristotle.
Reading the First Meditation allows us to read different interpretations into the different stages of doubt. For example, there is some debate as to whether Descartes intended his famous “Dream Argument” to suggest the universal possibility of dreaming, “that though there is waking experience, I can never know which moments are dreams and which are waking” or the possibility of a universal dream, “that my whole life is a dream and that there is no waking world”. If we read Descartes as suggesting the universal possibility of dreaming, we can explain an important distinction between the Dream Argument and the later “Evil Demon Argument.” The latter suggests that everything we know is false and that we cannot trust our senses. The Dream Argument, if meant to suggest the universal possibility of dreaming, suggests only that the senses are not always reliable. The Dream Argument questions Aristotelian thoughts, while the Evil Demon Argument does away with it altogether. The “Painter’s Analogy,” which draws on the Dream Argument, decides that mathematics and other purely intellectual studies are far more certain than astronomy or physics.
We should note that Descartes’ doubt is a practical and rational doubt. That is, the Meditator does not just doubt everything at random, but is providing solid reasons for his doubt at each stage. For instance, he rejects the possibility that he might be mad, since that would undercut the rationality that motivates his doubt. Descartes is trying to set up this doubt within a rational framework, and needs to maintain a claim to rationality for his arguments to proceed.
The Second Meditation is subtitled “The nature of the human mind, and how it is better known than the body” and takes place the day after the First Meditation. The Meditator decisively continues his search for certainty and to classify as false anything that is pointed in the directions of slightest doubt. Recalling the previous meditation, he supposes that what he sees does not exist, that his memory is faulty, that he has no senses and no body, that extension, movement and place are mistaken notions. Perhaps, he remarks, the only certain thing remaining is that there is no certainty.
The cogito argument, “I think, therefore I am”, is possibly the most famous single line in all of philosophy, and is considered the starting point for modern Western philosophy. In it, the Meditator finds his first hold on certainty after the radical skepticism he posited in the First Meditation. The cogito presents a picture of the world and of knowledge in which the mind is something that can know itself better than it can know anything else. In this conception, the mind ceases to be something that helps us know about the world and becomes something inside which we are locked.
After the cogito, the Meditator moves forward with the claim that he is a thing that thinks, an argument called the sum res cogitans. Regarding the claim “I am…in the strict sense only a thing that thinks,” the questions, what is meant by “thing,” and what “thinking” means have to be answered.
By “thing,” Descartes could simply be using the word as we do today, as an vague casual word when we do not want to be more specific. More likely, though, he is using it to mean substance, the fundamental and indivisible elements of Cartesian ontology. In this ontology, there are extended things (bodies) and thinking things (minds), and Descartes is here asserting that we are minds rather than bodies; “thinking” is also highly questionable. At the beginning of the Second Meditation, the Meditator has spreads sensory perception and into doubt, but by the end of the Second Meditation, sensing, imagining, willing, are incorporated as characteristics of the mind.
The rest of the Second Meditation concentrates on the “Wax Argument” with which Descartes hopes to show that we come to know things through the intellect rather than through the senses and that we know the mind better than anything else. His argument focuses on the process of change by which solid wax melts into a liquid puddle. The senses seem to tell us things about the world, and Descartes admits that what we know about the solid piece of wax we know through the senses. The senses can similarly inform us about the melted wax, but they cannot tell us that the melted wax and the solid wax are one and the same. The intellect can organize and make sense of what we perceive. The senses only perceive a incoherent clutter of information: the intellect is what helps us to understand it.
The Third Meditation, subtitled “The existence of God,” opens with the Meditator reviewing what he has ascertained to date. He is still doubtful of the existence of bodily things, but is certain that he exists and that he is a thinking thing that doubts, understands, wills, imagines, and senses. Having determined that he exists and that he is a thinking thing, the Meditator tries to determine how he can know these things, and whether he might come to know other things by similar means. He concludes that his knowledge of the cogito and the sum res cogitans are clear and distinct perceptions. Thus, he concludes, all clear and distinct perceptions, which he refers to as “the natural light”, must be certain.
The reasoning of this topic has two sides. On one hand, the cogito is certain because it is clearly and distinctly perceived. On the other hand, clear and distinct perceptions must be certain because they are the means by which the certainty of the cogito is achieved. There is also the difficulty raised with the case of geometry and arithmetic. These truths seem clear and distinct to us as well, but there is still the possibility that we are deceived with respect to them. And if God can deceive us of our clear and distinct perceptions, perhaps even the cogito can be cast back into doubt.
Descartes seems to want to escape the problems involved in clear and distinct perceptions by relying on God’s existence to make them true. However, Descartes also seems to want to prove God’s existence by claiming it as a clear and distinct perception.
The Meditator reasons that all ideas are mere forms of thought, and as a result, they are all equal. By this he means that they all have the same amount of formal reality.