Rene Descartes
Meditation One
Many people find it strange that Descartes begins his Meditations on First Philosophy by doubting. But given his goal this is understandable. He is searching for a foundation for all knowledge that is certain. As we mentioned before Descartes' world was turned upside down by the discovery of Copernicus. For obvious reasons, many people are beginning to question their knowledge. After all, if Aristotle could be that wrong about something as fundamental as whether the Earth goes around the sun or not what else might he have gotten wrong? This is what Descartes means when he says in the opening sentence of Meditation One "several years have now elapsed since I first became aware that I had accepted, even from my youth, many false opinions for true." In other words, he has good reason to doubt. The foundation for knowledge, if it exists, will be indubitable. So anything that can be doubted must be thrown out.
It is important to recognize that Descartes is very methodic about his doubting. He does not, as many believe, doubt everything. He proceeds slowly and systematically. However, Descartes’ standard for doubting is much different from ours. You may have, in a court of law context, heard the phrase "reasonable doubt." This is not the standard Descartes is using; many of the things he calls into question will not seem like things that it is reasonable to doubt. The standard Descartes is using is whether something can be logically doubted. That is, can we doubt the truth of such and without contradicting ourselves? This is a much broader notion of doubting and because of this, we will see that Descartes doubts many things that we would hardly think of as being doubtful. But as Descartes points out in paragraph 2, it will not be necessary to demonstrate something is false to call it into question. It will only be necessary to show that something can be doubted. After all that we are searching for is something that cannot, even logically, be doubted.
In paragraph 3 Descartes points out that everything he has learned before now he learned through sense experience. So we should begin by asking whether we can doubt the knowledge that comes from sense experience. Descartes offers us three reasons for doubting sense experience. First, the senses do sometimes deceive us. For example, if you've ever placed a stick into a body of water, it appears to be bent. We know the stick is not bent but our senses tell us it is. We could easily think of other cases of deception but the point is that if the senses deceive us sometimes who's to say they're not deceiving us all the time.
However, not wanting to go too quickly Descartes says that perhaps we need other reasons for doubting the senses. After all, just because they deceive us sometimes it does not necessarily mean they are deceiving us in all cases. Says Descartes, it seems unlikely that my senses are deceiving me about something as fundamental as being awake sitting here typing at my computer (this is my example which is a contemporary version of the Cartesian example in paragraph 4). However, we've all had vivid dreams that seemed so real we were surprised to awake from them. How can we be sure that this is not one of those dreams? Or to offer a more recent example, how can we be sure our life is not the product of some computer simulation like in The Matrix? Clearly, says Descartes, we cannot be certain and so must doubt the truth of sense experience.
Then, sense experience can be doubted and so we should not regard it as the certain foundation of our knowledge. Perhaps there is something else to base our knowledge on. After all, even when I dream, 2+3=5 and there seems little reason to doubt similar truths of mathematics. As he points out in paragraph 8 it may be that the physical sciences which depend on sense experience are uncertain but sciences like mathematics and geometry are where we have certainty unless we can think of any possible reason to doubt mathematics.
This is where things get a little strange. Descartes is looking for any reason to logically doubt. So, he reasons, we believe in a God who is very powerful and good but what if God is deceiving me? This seems contrary to God's nature and so Descartes offers another, even stranger, possibility in paragraph 12. What if some malignant demon "who is at once exceedingly potent and deceitful, has employed all his artifice to deceive me?" This would certainly cause me to doubt the truths of mathematics and also give me a third reason for doubting sense experience. After all, any being capable of deceiving me about mathematics could also cause me to be deceived about my senses. Maybe we are in the matrix!
So Descartes concludes the first meditation by doubting "the sky, the air, the earth, colors, figures, sounds, and all external things." Also, he says "I will consider myself as without hands, eyes, flesh, blood, or any of the senses." And he resolves to continue in this doubt until something certain can be found. But before we continue our search for this certainty let's consider something interesting. Descartes seems to doubt among other things that he has a body. This is what he means after all by saying "I will consider myself as without hands..." How is this possible? Does this accord with Descartes’ standard of doubt? Can we logically doubt the body? Well, certainly if I were the same thing as my body this would seem to be impossible (more on this below). The only way that I can doubt the existence of my body is if I am different from my body. This is very significant because we have here already a hint of Cartesian dualism. I can doubt my body which must mean I am different from my body. Whatever "I" am is not entirely, if at all, connected to my body. As it turns out this gives Descartes the clue not only to his metaphysics but also, the certainty he is searching for.
Meditation Two
He begins Meditation Two in despair of ever finding the certainty he seeks. But he resolves to continue looking for it or at least discover there is no such certainty. So he continues to think remembering that yesterday (when he first meditated) he doubted all that could be doubted and was postulating that he was being deceived. So he thinks to himself "I doubt," "I am being deceived." But wait! Don't I have to exist for these things to be possible? How could I be deceived if I didn't exist? Could I doubt my existence? No! No matter how much someone is deceiving me I cannot be made to doubt my existence. "Doubtless, then, I exist, since I am being deceived." So this is the certainty we have been searching for: I exist. How do I know this? I merely have to think. My thinking tells me with certainty that I exist, giving rise to Descartes' most famous insight. Perhaps the most famous sound bite in philosophy: Cogito ergo sum. I think, therefore I am.
So where do we go from here? The next question we should address is the nature of this "I." What am I Descartes asks in paragraph 5 of the second meditation? After some reflection, he arrives at the simplest definition he can think of in paragraph 8. I am "a thinking thing." And what is a thinking thing? Easy, it’s a thing that thinks! But what is this precisely? Descartes enumerates: "It is a thing that doubts, understands, conceives, affirms, denies, wills, refuses; that imagines also, and perceives."
One aspect of this definition will no doubt seem strange to you given what we have doubted. That is the last part; perceiving. How can thinking be connected with perceiving since we doubted our senses and, even more, the body that gives us these perceptions through the senses? The answer turns out to be a key element in Descartes' notion of the mind. He calls this the faculty of judgment.
To illustrate what he means by the faculty of judgment Descartes offers us an example in paragraph 11. Let's examine a piece of wax. We perceive its attributes through the senses: it has a certain shape, smell, taste, texture, etc. If we hold it close to the fire all these attributes change. The shape changes, the smell, the texture, etc. Now, is it the same piece of wax? We would surely say that it is but how can we say this? We are not making this claim based on sense experience since all the sensory experiences we get from the wax have changed. We must be making this claim based on a mental inspection of the wax. That is, we must be judging that it is the same piece of wax.
Still, this example may not suffice so Descartes offers us a second, and if this doesn't help I will offer a third example. In paragraph 13 Descartes asks us to consider the people we see "passing on in the street below, as observed from a window." We say that we see people passing by when in fact all we see are "hats and cloaks that might cover artificial machines." How do we know they are people? We judge that they are. Or better, if you don't like supposing that the people you see maybe robots consider this example. Have you ever been to the mall or some other public place walking behind someone and you think you recognize who it is? So you call out to them "hey Jim!" But when the person turns around it’s not whom you thought it was. You made a judgment (based on limited sense experience) that it was your friend. The point of all of these examples is that perception is governed by an important mental component. The sense experiences are meaningless unless they are processed by this act of thinking, this faculty of judgment.
So at the end of the second meditation what do we know? We know one thing for certain: I exist. And we know by deduction what this "I" is a thinking thing. From here we might like to make inferences about the objects of sense experience; that is the world around us. But we must not go too fast. Remember, we are still maintaining that we are being deceived by some evil demon. So what we need to do is prove the existence of God and show that He is not a deceiver. This will, at least to Descartes' satisfaction, eliminate the problem of deception and allow us to investigate the external world. We will examine Descartes' proof for the existence of God in the third meditation.
Third Meditation
It may sound strange to you that we will be attempting to prove the existence of God. As we will see in the philosophy of religion section of the class, this is a very important issue and one that has occupied many philosophers. Like many who attempt to prove God's existence, Descartes already believes in God. Given this you may wonder, what's the point in the exercise of proof? For Descartes the point is twofold. First, it is helpful to provide a philosophical justification for the things we believe. This gives us good reasons for our beliefs and, other things being equal, it seems better to have justified beliefs than unjustified ones. Secondly, for Descartes' project to work, we’ll need to establish not only that God exists but is not a deceiver. Otherwise, we will be unable to make any judgments about the external world without being susceptible to doubt.
It is important, to begin with, a word about the kind of evidence Descartes will be offering to prove God's existence. Since we currently doubt the truth of sense experience we cannot use this evidence. We must use only the evidence at our disposal based on what we know for certain. I exist as a thinking thing. So we must begin with thoughts.
In paragraph 5 Descartes enumerates three types of thoughts. First, there are ideas, which are, strictly speaking, pictures in the mind. We can picture things to ourselves and these are ideas. Second, our emotions, or what Descartes calls volitions or affections. And third, Judgments which we have already discussed concerning perception. One important example of a judgment that we will investigate later is the judgment that our ideas of physical objects come from the objects themselves. As Descartes points out judgments are the only thoughts that can be either true or false. Ideas are simply pictures and so cannot be true or false. If we say that one of these ideas corresponds to a particular object then we are making a judgment which is, of course, either true or false. We are either correct or incorrect about the judgment that such an idea represents such an object.
The next question is what are the possible sources of our ideas? There are three: the ideas could come from external objects in which case they are called "adventitious," the ideas could be invented by me in which case they are called "fictitious," and finally they could be inborn in which case they are called "innate." For all, we know all the ideas that we have could be invented. As of now, we have no justification for making judgments about the source of ideas. What we need is a method for making such a judgment and then we will need to make a judgment about the source of one idea in particular; namely the idea of God. This will constitute our proof for God's existence.
We'll begin with a self-evident proposition which Descartes describes in paragraph 14 where he says "it is manifest by the natural light that there must be at least as much reality in the efficient and total cause as in its effect." Simply put this means that an effect cannot have more reality than its cause. An effect cannot arise out of something which cannot be its cause. Perhaps an example will help. Consider a piece of wood. If we want to heat the piece of wood we have three choices to use: a piece of ice, another piece of wood, or fire. We can't use ice it; doesn't have nearly as much heat as the piece of wood. We can't use another piece of wood either. What we need is something with more heat than a piece of wood; we need fire. Another way of thinking about this is that fire possesses the reality of heat in greater quantity than the piece of wood and so it can be the cause of the piece of wood heating up.
OK if that's clear let's address how Descartes describes this. In paragraph 13 he refers to two kinds of reality: formal and objective. He's using a type of vocabulary familiar to his audience. The scholastic philosophers of the middle ages talked this way as well. Strangely enough, when he refers to "objective reality" he's talking about the reality of ideas. When Descartes refers to "formal reality" he's talking about the reality of objects.
The proof for God's existence depends on the nature of the idea of God. Descartes defines this idea in paragraph 22 where he says "by the name God, I understand a substance infinite, eternal, immutable, independent, all-knowing, all-powerful, and by which I, and every other thing that exists, if any such there be, were created." This idea, says Descartes, has more objective reality than we do formal reality. Why does he say this? In particular the attribute of God being infinite concerns him. We are finite but our idea of God is of an infinite substance. The finite is less real than the infinite so our idea of God has greater reality (as an idea) than we have. We cannot be the cause of our idea of God. There is only one possible cause for the idea of God and that is God himself. Therefore, God exists.
Here is a summary of the proof.
1. There must be at least as much reality in the efficient and total cause as in its effect.
2. The idea of God is a substance infinite, eternal, immutable, independent, all-knowing, all-powerful, and by which I, and every other thing that exists, if any such there be, were created.
3. This idea contains more objective reality than we contain formal reality.
4. The cause of my idea of God cannot be me.
5. The cause of the idea of God must contain as much (or more) formal reality as the idea itself.
THEREFORE: God exists.
In paragraph 37 Descartes considers "how I received this idea from God." The idea cannot be gained from sense experience (remember we are still doubting it) and we could not invent the idea ourselves (because of the proof we have just considered. An important implication of this is that the idea cannot come from any human mind. Human beings, including our parents or others, could not have given us the idea of God. Even if they did, we would still need to answer where they got the idea from. The only option left, as Descartes points out, is that the idea of God is innate, implanted in me "that it might serve, as it were, for the mark of the workman on his work."
Having proved that God exists as a being with all perfections we turn briefly to consider whether God could be a deceiver. It seems that this is impossible given the fact, as Descartes points out in paragraph 2 of the fourth meditation. Since deception is itself an imperfection and God has no imperfections, God could not be a deceiver. This of course raises a question that we need to address which is quite simple if God is not responsible for our errors what is. This will be addressed in Meditation Four.
Meditation Four
To discover the source of error we need to consider two faculties of thought. The first Descartes variously refers to as the faculty of understanding or the faculty of cognition. The second we have encountered before is the faculty of judgment which he sometimes refers to as the faculty of will or the "power of free choice." In paragraph 8 of the fourth meditation, Descartes offers us an explanation of these faculties and how they generate an error.
The faculty of cognition simply refers to our capacity to have ideas in our minds. As Descartes puts it this faculty "neither affirms nor denies anything but merely apprehend[s] the ideas regarding which I may form a judgment." You can think of this faculty as the ability to picture ideas in our mind, be they ideas of objects or concepts. This faculty is limited since we do not apprehend every idea that can be thought. However, it is not its limit that causes our errors. After all, there is no reason to think that God should have given us an infinite faculty of cognition. So this limit is not due to a lack of something we should have. In Descartes’ words, we do not lack knowledge as a privation but merely a negation. Again he is speaking to an audience familiar with scholastic terminology. To lack something as privation is to lack something one is supposed to have whereas to lack something as a negation is simply to not have something. For example, the lack of the ability to see is shared by both a stone and a blind man. But they cannot see in different ways. After all, the blind man is supposed to be able to see (people are supposed to be able to see after all!) but the stone was never meant to see. So we say that the blind man lacks sight as a privation but the stone lacks it as a negation. Applied to our faculty of cognition its finite nature is merely a negation.
On the other hand, our faculty of will is infinite. Descartes says that if we examine it carefully we will find it to be "so great that I am unable to conceive the idea of another that shall be more and extended." Of course, God's faculty of will is "incomparably greater" than ours but this is due, in large part, to God's infinite knowledge. So as an infinite faculty our power of free choice cannot be the source of our error.
The source of our error can be found in the difference between the two faculties. Our faculty of cognition is finite but our faculty of will is infinite. Think of it this way. The faculty of cognition allows me to hold ideas in my mind. The faculty of will allows me to decide, or in Descartes' words to affirm or deny, whether those ideas are true or false. It goes without saying that if I know the ideas I apprehend in my mind I will be in a much better position to affirm or deny their truth. However, if I affirm or deny an idea without such knowledge my chances for error increase greatly. The thing is my affirming or denying (that is my power of free choice) is not constrained by my knowledge of an idea. That's what it means for the faculty of will to be infinite. So I can affirm or deny the truth of an idea without actually knowing whether it’s true or false. And that is the source of error. If you find this strange just think about this. I will give you a statement that you will understand (i.e. it will be in your faculty of cognition) though you may not know whether it’s true or false. Never mind that though I will then ask you to affirm or deny it. You will be able to do so without any trouble at all but since you don't know whether it’s true or false you will likely as not be in error about your judgment.
OK here goes. Soren Kierkegaard was an 18th-century Austrian philosopher. Now you should understand what that sentence says even if you're not quite sure whether it’s true or false. So it’s in your faculty of cognition; you apprehend it as an idea. Now make a judgment about it: true or false? If you don't know who Kierkegaard is you have a fifty-fifty chance of being correct. Those are not good odds and just prove the point Descartes is making. Our chance for error goes up if we make judgments that go beyond what we know of.
The moral of the story is that there are two ways to decrease our chance of making judgments in error. The first is to restrict our judgments to things we have a certain knowledge of. If we're not sure we should suspend judgment. The second is to increase our knowledge. The more we know the better our judgments will be. It must be true what Bacon said: "knowledge is power." Oh by the way Kierkegaard, was from Denmark and lived in the 19th century.
Meditation Five
Having discovered the source of error we can proceed to investigate the rest of the world; the existence of material things. But first, we need to make one small philosophical detour in Meditation Five. We need to consider the essence of material things. The reason for this is quite simple. As of now, we are still in doubt about the source of our ideas of material objects; they may be adventitious or they may be fictitious (remember what those words mean?). In any case, we are still contemplating the ideas. Now, if it turns out that the very concept of a material object is inherently contradictory then we need not wonder whether any such things exist because it will be impossible for them to exist. So if their essence is impossible so too their existence will be impossible.
By essence, Descartes means those attributes which you cannot help but think about when conceiving of any given object. Take a triangle, for instance. When you think of a triangle you quite naturally think of three sides and 180 degrees of angles. You can't help but think of these attributes. We have, in Descartes' words, a clear and distinct idea of these attributes being attached to the object "triangle." As he points out in paragraph 7 of the fifth meditation "whatever is clearly and distinctly known is true."
The interesting turn in Meditation Five occurs in paragraph 8 where Descartes says "if because I can draw from my thought the idea of an object, it follows that all I clearly and distinctly apprehend to pertain to this object, does in truth belong to it, may I not from this derive an argument for the existence of God?" That's right Descartes is going to give us another proof for the existence of God. Why? Many scholars have speculated on this and since Descartes does not tell us we may never know for sure. However, in a series of replies to objections that Descartes wrote he does give us a clue. While the first proof deals with the cause of the idea of God, this second proof allows us to focus more on the attributes of God. So it’s not that this proof provides stronger evidence or that this proof is meant to succeed where the other proof failed. They are simply providing different perspectives on the existence of God.
This proof also turns out to be simpler to relate to as well. We can state it as a three-stage argument (in logic these are called syllogisms). Premise one: God is a being who contains all perfections. Premise two: Existence is perfection. Conclusion: God must exist.
Many people find this proof very elegant in its simplicity but perhaps just as many find it deeply flawed. Since it is not our purpose here to deal with the philosophy of religion questions I will not go into too much detail but I will share one particular objection offered by Immanuel Kant.
The proof seems to hinge on the second premise that existence is perfection. But this can only be true (says Kant) if existence is some kind of attribute. This, however, seems to be untrue. Of course, existence appears to be an attribute. Consider the following sentences:
That table is red.
That table is.
They both appear grammatically similar and clearly, the first one is attributing red to the table. So "red" is an attribute. It seems as if the second one is doing the same thing but with existence. However, this is not what is going on. As Kant points out in his Critique of Pure Reason "being is not a real predicate." That is his way of saying existence is not an attribute. As Kant puts it "it is merely the positing of a thing, or certain determinations, as existing in themselves." It is simply a logical fallacy to go from the "logical possibility of concepts to the real possibility of objects." This is what Descartes seems to be doing.
To see the force of this objection consider the following example. Suppose I say "I hope to have a son someday." You certainly understand what this means and it’s not strange at all. Also if I were to say "I hope my future son likes to play golf" nothing strange seems to be going on there (unless you happen not to like golf!). But suppose I were to say "I hope my future son exists." What could this possibly mean? It seems very strange to say precisely because existence is not a real attribute. Of course, my future son will exist. That is if I have a son in the future his existence is implied. That's what Kant means by saying that being is "merely the positing of a thing."
Alas for us this is where we will have to leave things with God and essence and existence. Descartes' consideration of essence has been to establish that the essence of material things is comprehensible. And based on what we've said so far and, with a few additions in the sixth meditation, it will turn out to be perfectly comprehensible, thus opening the door for us to infer, actually deduce, the existence of material things. It is to this task that we will turn next.
Meditation Six
We can now proceed to the deduction of material things. As Descartes says in the first paragraph of the sixth meditation "I at least know with certainty that such things may exist." We know this because we have examined their essence and in the example of the triangle have discovered that there is nothing contradictory to lead us to suppose that these things cannot exist. But since essence is different from existence (except as in the case of God whose essence is to exist) we need to consider their existence separately.
Descartes begins by making a distinction between the imagination and what he calls pure intellect. In many cases, these faculties are used together but to show their difference he suggests that we conceive of a chiliogon which is a thousand-sided figure. While it is possible to conceive it, we cannot imagine it by which Descartes means to view it "with the eyes of my mind." Imagination requires a special separate faculty from thinking and this faculty is what gives us the clue to the deduction of material substance. The way he puts it is that "a special effort of mind is necessary to the act of imagination, which is not required to conceiving or understanding." This special faculty he refers to, in paragraph 10 as the "passive faculty of perception." Before getting to this Descartes provides us with a summary of the previous meditations in paragraphs 5 through 9.
In paragraph 10 Descartes clarifies what he means by the passive faculty of perception. There are many perceptions that we have that we are not choosing to have. The vast majority of our sense experiences are not of our choosing. For example, if you look out your window you have no choice but to see what is there. It’s not like you can make up your scene to view. So what could explain this fact? There are, in Descartes' view two possible explanations. 1. God is causing these scenes. That is, the scenes (the perceptions) are not really there but just put into our minds by God. 2. The external objects themselves are causing our perceptions of them. You may believe that there is a third option namely that we are creating the perceptions but remember they are passive; involuntary. If we were causing them you'd think we would have control over them. So of the two options above, we need to figure out which is the correct one. The first is a problem because it makes God a deceiver which we have established is impossible. So there is only one option left. It must be that the external objects themselves are causing our perceptions. Therefore, material things exist. This, then, is the deduction of material things.
So Descartes has deduced the existence of the self, God, and material things; in that order. And to come full circle we conclude with some considerations of the self more informed than when we began our investigation. In paragraph 12 Descartes says that "there is nothing which that nature teaches me more expressly or more sensibly than that I have a body." We alluded to this earlier that in Descartes' view we are not the same as our body. What we are can be described as a thinking thing; a thinking thing that has a body not a thinking thing that is a body. This is an important distinction and is a distinct element in Cartesian metaphysics. Descartes is a dualist which means he believes that there are two distinct substances in the world: mental substance (the mind) and physical substance (the body). They have fundamentally different attributes. The mind is characterized by the attribute of thought. The body is characterized by the attribute of extension; which is taking up space.
The next step is taken in paragraph 13 where Descartes says "nature likewise teaches me by these sensations of pain, hunger, thirst, etc., that I am not only lodged in my body as a pilot in a vessel, but that I am besides so intimately conjoined, and as it was intermixed with it, that my mind and body compose a certain unity.” Herein is perhaps Descartes' greatest contribution to modern philosophy; a problem! If mind and body are so radically different how can they compose a unity? Another way of thinking about this is as follows. Descartes claims that there is an interaction between mind and body. But, given their differences, how is this interaction possible? This is the mind-body problem. It has occupied philosophers ever since Descartes' time.
Mind-Body Problem
Descartes himself provides an answer that is nothing short of shocking in its inadequacy. This has led many scholars to speculate that Descartes never saw this for the problem it is. We will address his attempted solution and then consider some solutions offered by contemporaries of Descartes. Descartes points out, in paragraph 20, that the mind and body do not interact at every point in the body. The locus of interaction is in the brain. It is very important to remember that for Descartes the mind is NOT the brain. The mind is a non-physical substance whereas the brain is part of the body. So the mind and body interact in the brain. To be specific Descartes says that the location of this interaction is the pineal gland. There were two reasons for postulating this as the location. First, it is centrally located in the brain and the only part not divided into halves; like the two hemispheres of the brain. Second, it was anybody's guess what the pineal gland did at the time and so this is as good a job as any for it.
The problem with this answer, of course, is that it doesn't address the question of how the mind and body interact, but rather, where they interact. We are still left wondering how to explain interaction and this is where Descartes leaves it.
There are two ways to deal with the mind-body problem; that is, the problem of interaction. We can try to explain the interaction or we can simply deny that there is any interaction. Surprisingly enough, the latter has been the more common approach. The reason for this is understandable. Explaining exactly how mind and body interact turns out to be very difficult. It is much easier to simply deny interaction entirely since on this approach there is nothing left to explain. Well, nothing except why there appears to be interaction. Three of Descartes' contemporaries attempted to do this while still preserving dualism.
The first was a philosopher named Nicolas Malebranche. He agreed with Descartes' dualism of mind and matter. However, he denied that the two substances interacted. Granted, mind and body appear to interact but this appearance is misleading. The real story is much different; and much stranger. The mind and body operate according to two separate causal series. We are in control of our mental faculties and so have some control over the causes and effects of the mental. But when the mental "causes" the physical it is nothing more than an "occasional" cause. That is to say, it is not the direct cause of what happens in the body. Rather, it is the signal if you will for the cause to take effect. In this case, the ultimate cause is God. So on the occasion when I will act in a certain way God causes my body to so behave. I told you it was weird. But believe it or not Malebranche's philosophy was "a considerable success." So says the historian Frederich Coppleston in his definitive nine-volume history of philosophy. This success was due in large part to what occasionalism stood against; materialism and empiricism both of which were regarded as damaging to God and religious faith. Sometimes you have to pick the lesser of two evils!
Given our probable reluctance to accept occasionalism we can consider other options. A second attempt to deny interaction was proposed by the German philosopher Gottfried Leibniz. Like Malebranche and Descartes, Leibniz is a dualist so he believes in the fundamental difference between mind and matter. However, he denies the interaction. Again we are left with the task of explaining the apparent interaction of mind and body. To do so Leibniz suggests a metaphor. Consider two clocks exactly alike in every way. We wind them up and set them to the same time. Then we let them work. Do you imagine that they will keep the same time? Within reason of course let's not get too carried away. But yes, they will keep pretty much the same time. Is that because one clock is causing the other to keep the same time? Is there any interaction between the two clocks at all? Of course not. The only reason they seem to interact (i.e. keep the same time) is because they were started at the same time. It’s the same with the mind and body. Through what Leibniz terms a "pre-established harmony" the mind and body were set (as it were) to run in sync and do so. Not because of any interaction mind you, but because God set them up at the same time.
This idea also enjoyed quite a wide popularity, especially among the scientists of the day who were interested in mechanistic explanations but wanted to preserve a place for God in the grand scheme of things. In particular, Sir Isaac Newton used the clock analogy to explain the universe with God as the one who starts the clock and lets it go. This clock analogy was to appear again in 1804 when William Paley used it to prove the existence of God (more on this anon).
A third attempt to solve the problem of interaction was offered by the Dutch philosopher Baruch Spinoza. He is somewhat different from the previous philosophers in that he immediately disagrees with the Cartesian notion that they are two fundamentally different substances. Wrong says, Spinoza. Given the definition of substance as "that which is in itself and is conceived through itself" neither mind nor body is substance. There can be only one substance. However, this one substance has many attributes, two of which are thought (which characterizes mind) and extension (which characterizes body). Depending on which perspective you take you can perceive the one substance as having either one attribute or the other or some other attribute entirely. So this one substance can be seen from dual aspects. And this is what we refer to his theory as the dual-aspect theory. This can also be referred to as "property dualism" as opposed to "substance dualism." We say property dualism because Spinoza refers to the dual attributes (or properties) of thought and extension. Descartes, of course, is a substance dualist because he refers to two substances: mind and body. By now you've probably guessed what the one substance is in Spinoza's theory: God.
Aside from these three theories, each of which had strong advocates, there are two other possibilities for dealing with the problem of interaction. These may be termed even more radical than the previous three if you can believe that. What each of the previous theories has in common is their acceptance, in some form, of the basic principle of dualism. But we can also deal with the problem of interaction by denying dualism altogether. What we then end up with is an entirely new metaphysical theory: monism.
Monism is the view that everything is composed of one substance and has two versions. The first version of monism, which we will consider in more detail later in the book, is materialism. This view postulates that everything in the universe is composed solely of physical substance. So when we refer to the mind or soul we are NOT referring to a non-physical entity. The mind, if it exists at all, must be something physical (like the brain). A contemporary of Descartes named Thomas Hobbes advocated this idea. It is very popular in some scientific quarters even to this day.
The second version of monism postulates that everything in the universe is the product of mental substance. On this view, there is no physical substance at all, only minds and the ideas in them. This theory is called idealism and gained some popularity in the 18th century through the work of the Irish philosopher George Berkeley. One of the implications of this view is that for something to exist it must be perceived. In this respect, it bears quite a striking similarity to modern quantum physics and it was Werner Heisenberg who recognized this connection and ran with it. Given the applicability of both types of monism to contemporary science, it’s no small wonder that we're trying to find a way to unify disparate theories today! We'll deal with these issues later as well. Our next task (after taking an exam of course!) will be to look at more recent attempts to deal with the problem of dualism and the nature of the mind.
Many people find it strange that Descartes begins his Meditations on First Philosophy by doubting. But given his goal this is understandable. He is searching for a foundation for all knowledge that is certain. As we mentioned before Descartes' world was turned upside down by the discovery of Copernicus. For obvious reasons, many people are beginning to question their knowledge. After all, if Aristotle could be that wrong about something as fundamental as whether the Earth goes around the sun or not what else might he have gotten wrong? This is what Descartes means when he says in the opening sentence of Meditation One "several years have now elapsed since I first became aware that I had accepted, even from my youth, many false opinions for true." In other words, he has good reason to doubt. The foundation for knowledge, if it exists, will be indubitable. So anything that can be doubted must be thrown out.
It is important to recognize that Descartes is very methodic about his doubting. He does not, as many believe, doubt everything. He proceeds slowly and systematically. However, Descartes’ standard for doubting is much different from ours. You may have, in a court of law context, heard the phrase "reasonable doubt." This is not the standard Descartes is using; many of the things he calls into question will not seem like things that it is reasonable to doubt. The standard Descartes is using is whether something can be logically doubted. That is, can we doubt the truth of such and without contradicting ourselves? This is a much broader notion of doubting and because of this, we will see that Descartes doubts many things that we would hardly think of as being doubtful. But as Descartes points out in paragraph 2, it will not be necessary to demonstrate something is false to call it into question. It will only be necessary to show that something can be doubted. After all that we are searching for is something that cannot, even logically, be doubted.
In paragraph 3 Descartes points out that everything he has learned before now he learned through sense experience. So we should begin by asking whether we can doubt the knowledge that comes from sense experience. Descartes offers us three reasons for doubting sense experience. First, the senses do sometimes deceive us. For example, if you've ever placed a stick into a body of water, it appears to be bent. We know the stick is not bent but our senses tell us it is. We could easily think of other cases of deception but the point is that if the senses deceive us sometimes who's to say they're not deceiving us all the time.
However, not wanting to go too quickly Descartes says that perhaps we need other reasons for doubting the senses. After all, just because they deceive us sometimes it does not necessarily mean they are deceiving us in all cases. Says Descartes, it seems unlikely that my senses are deceiving me about something as fundamental as being awake sitting here typing at my computer (this is my example which is a contemporary version of the Cartesian example in paragraph 4). However, we've all had vivid dreams that seemed so real we were surprised to awake from them. How can we be sure that this is not one of those dreams? Or to offer a more recent example, how can we be sure our life is not the product of some computer simulation like in The Matrix? Clearly, says Descartes, we cannot be certain and so must doubt the truth of sense experience.
Then, sense experience can be doubted and so we should not regard it as the certain foundation of our knowledge. Perhaps there is something else to base our knowledge on. After all, even when I dream, 2+3=5 and there seems little reason to doubt similar truths of mathematics. As he points out in paragraph 8 it may be that the physical sciences which depend on sense experience are uncertain but sciences like mathematics and geometry are where we have certainty unless we can think of any possible reason to doubt mathematics.
This is where things get a little strange. Descartes is looking for any reason to logically doubt. So, he reasons, we believe in a God who is very powerful and good but what if God is deceiving me? This seems contrary to God's nature and so Descartes offers another, even stranger, possibility in paragraph 12. What if some malignant demon "who is at once exceedingly potent and deceitful, has employed all his artifice to deceive me?" This would certainly cause me to doubt the truths of mathematics and also give me a third reason for doubting sense experience. After all, any being capable of deceiving me about mathematics could also cause me to be deceived about my senses. Maybe we are in the matrix!
So Descartes concludes the first meditation by doubting "the sky, the air, the earth, colors, figures, sounds, and all external things." Also, he says "I will consider myself as without hands, eyes, flesh, blood, or any of the senses." And he resolves to continue in this doubt until something certain can be found. But before we continue our search for this certainty let's consider something interesting. Descartes seems to doubt among other things that he has a body. This is what he means after all by saying "I will consider myself as without hands..." How is this possible? Does this accord with Descartes’ standard of doubt? Can we logically doubt the body? Well, certainly if I were the same thing as my body this would seem to be impossible (more on this below). The only way that I can doubt the existence of my body is if I am different from my body. This is very significant because we have here already a hint of Cartesian dualism. I can doubt my body which must mean I am different from my body. Whatever "I" am is not entirely, if at all, connected to my body. As it turns out this gives Descartes the clue not only to his metaphysics but also, the certainty he is searching for.
Meditation Two
He begins Meditation Two in despair of ever finding the certainty he seeks. But he resolves to continue looking for it or at least discover there is no such certainty. So he continues to think remembering that yesterday (when he first meditated) he doubted all that could be doubted and was postulating that he was being deceived. So he thinks to himself "I doubt," "I am being deceived." But wait! Don't I have to exist for these things to be possible? How could I be deceived if I didn't exist? Could I doubt my existence? No! No matter how much someone is deceiving me I cannot be made to doubt my existence. "Doubtless, then, I exist, since I am being deceived." So this is the certainty we have been searching for: I exist. How do I know this? I merely have to think. My thinking tells me with certainty that I exist, giving rise to Descartes' most famous insight. Perhaps the most famous sound bite in philosophy: Cogito ergo sum. I think, therefore I am.
So where do we go from here? The next question we should address is the nature of this "I." What am I Descartes asks in paragraph 5 of the second meditation? After some reflection, he arrives at the simplest definition he can think of in paragraph 8. I am "a thinking thing." And what is a thinking thing? Easy, it’s a thing that thinks! But what is this precisely? Descartes enumerates: "It is a thing that doubts, understands, conceives, affirms, denies, wills, refuses; that imagines also, and perceives."
One aspect of this definition will no doubt seem strange to you given what we have doubted. That is the last part; perceiving. How can thinking be connected with perceiving since we doubted our senses and, even more, the body that gives us these perceptions through the senses? The answer turns out to be a key element in Descartes' notion of the mind. He calls this the faculty of judgment.
To illustrate what he means by the faculty of judgment Descartes offers us an example in paragraph 11. Let's examine a piece of wax. We perceive its attributes through the senses: it has a certain shape, smell, taste, texture, etc. If we hold it close to the fire all these attributes change. The shape changes, the smell, the texture, etc. Now, is it the same piece of wax? We would surely say that it is but how can we say this? We are not making this claim based on sense experience since all the sensory experiences we get from the wax have changed. We must be making this claim based on a mental inspection of the wax. That is, we must be judging that it is the same piece of wax.
Still, this example may not suffice so Descartes offers us a second, and if this doesn't help I will offer a third example. In paragraph 13 Descartes asks us to consider the people we see "passing on in the street below, as observed from a window." We say that we see people passing by when in fact all we see are "hats and cloaks that might cover artificial machines." How do we know they are people? We judge that they are. Or better, if you don't like supposing that the people you see maybe robots consider this example. Have you ever been to the mall or some other public place walking behind someone and you think you recognize who it is? So you call out to them "hey Jim!" But when the person turns around it’s not whom you thought it was. You made a judgment (based on limited sense experience) that it was your friend. The point of all of these examples is that perception is governed by an important mental component. The sense experiences are meaningless unless they are processed by this act of thinking, this faculty of judgment.
So at the end of the second meditation what do we know? We know one thing for certain: I exist. And we know by deduction what this "I" is a thinking thing. From here we might like to make inferences about the objects of sense experience; that is the world around us. But we must not go too fast. Remember, we are still maintaining that we are being deceived by some evil demon. So what we need to do is prove the existence of God and show that He is not a deceiver. This will, at least to Descartes' satisfaction, eliminate the problem of deception and allow us to investigate the external world. We will examine Descartes' proof for the existence of God in the third meditation.
Third Meditation
It may sound strange to you that we will be attempting to prove the existence of God. As we will see in the philosophy of religion section of the class, this is a very important issue and one that has occupied many philosophers. Like many who attempt to prove God's existence, Descartes already believes in God. Given this you may wonder, what's the point in the exercise of proof? For Descartes the point is twofold. First, it is helpful to provide a philosophical justification for the things we believe. This gives us good reasons for our beliefs and, other things being equal, it seems better to have justified beliefs than unjustified ones. Secondly, for Descartes' project to work, we’ll need to establish not only that God exists but is not a deceiver. Otherwise, we will be unable to make any judgments about the external world without being susceptible to doubt.
It is important, to begin with, a word about the kind of evidence Descartes will be offering to prove God's existence. Since we currently doubt the truth of sense experience we cannot use this evidence. We must use only the evidence at our disposal based on what we know for certain. I exist as a thinking thing. So we must begin with thoughts.
In paragraph 5 Descartes enumerates three types of thoughts. First, there are ideas, which are, strictly speaking, pictures in the mind. We can picture things to ourselves and these are ideas. Second, our emotions, or what Descartes calls volitions or affections. And third, Judgments which we have already discussed concerning perception. One important example of a judgment that we will investigate later is the judgment that our ideas of physical objects come from the objects themselves. As Descartes points out judgments are the only thoughts that can be either true or false. Ideas are simply pictures and so cannot be true or false. If we say that one of these ideas corresponds to a particular object then we are making a judgment which is, of course, either true or false. We are either correct or incorrect about the judgment that such an idea represents such an object.
The next question is what are the possible sources of our ideas? There are three: the ideas could come from external objects in which case they are called "adventitious," the ideas could be invented by me in which case they are called "fictitious," and finally they could be inborn in which case they are called "innate." For all, we know all the ideas that we have could be invented. As of now, we have no justification for making judgments about the source of ideas. What we need is a method for making such a judgment and then we will need to make a judgment about the source of one idea in particular; namely the idea of God. This will constitute our proof for God's existence.
We'll begin with a self-evident proposition which Descartes describes in paragraph 14 where he says "it is manifest by the natural light that there must be at least as much reality in the efficient and total cause as in its effect." Simply put this means that an effect cannot have more reality than its cause. An effect cannot arise out of something which cannot be its cause. Perhaps an example will help. Consider a piece of wood. If we want to heat the piece of wood we have three choices to use: a piece of ice, another piece of wood, or fire. We can't use ice it; doesn't have nearly as much heat as the piece of wood. We can't use another piece of wood either. What we need is something with more heat than a piece of wood; we need fire. Another way of thinking about this is that fire possesses the reality of heat in greater quantity than the piece of wood and so it can be the cause of the piece of wood heating up.
OK if that's clear let's address how Descartes describes this. In paragraph 13 he refers to two kinds of reality: formal and objective. He's using a type of vocabulary familiar to his audience. The scholastic philosophers of the middle ages talked this way as well. Strangely enough, when he refers to "objective reality" he's talking about the reality of ideas. When Descartes refers to "formal reality" he's talking about the reality of objects.
The proof for God's existence depends on the nature of the idea of God. Descartes defines this idea in paragraph 22 where he says "by the name God, I understand a substance infinite, eternal, immutable, independent, all-knowing, all-powerful, and by which I, and every other thing that exists, if any such there be, were created." This idea, says Descartes, has more objective reality than we do formal reality. Why does he say this? In particular the attribute of God being infinite concerns him. We are finite but our idea of God is of an infinite substance. The finite is less real than the infinite so our idea of God has greater reality (as an idea) than we have. We cannot be the cause of our idea of God. There is only one possible cause for the idea of God and that is God himself. Therefore, God exists.
Here is a summary of the proof.
1. There must be at least as much reality in the efficient and total cause as in its effect.
2. The idea of God is a substance infinite, eternal, immutable, independent, all-knowing, all-powerful, and by which I, and every other thing that exists, if any such there be, were created.
3. This idea contains more objective reality than we contain formal reality.
4. The cause of my idea of God cannot be me.
5. The cause of the idea of God must contain as much (or more) formal reality as the idea itself.
THEREFORE: God exists.
In paragraph 37 Descartes considers "how I received this idea from God." The idea cannot be gained from sense experience (remember we are still doubting it) and we could not invent the idea ourselves (because of the proof we have just considered. An important implication of this is that the idea cannot come from any human mind. Human beings, including our parents or others, could not have given us the idea of God. Even if they did, we would still need to answer where they got the idea from. The only option left, as Descartes points out, is that the idea of God is innate, implanted in me "that it might serve, as it were, for the mark of the workman on his work."
Having proved that God exists as a being with all perfections we turn briefly to consider whether God could be a deceiver. It seems that this is impossible given the fact, as Descartes points out in paragraph 2 of the fourth meditation. Since deception is itself an imperfection and God has no imperfections, God could not be a deceiver. This of course raises a question that we need to address which is quite simple if God is not responsible for our errors what is. This will be addressed in Meditation Four.
Meditation Four
To discover the source of error we need to consider two faculties of thought. The first Descartes variously refers to as the faculty of understanding or the faculty of cognition. The second we have encountered before is the faculty of judgment which he sometimes refers to as the faculty of will or the "power of free choice." In paragraph 8 of the fourth meditation, Descartes offers us an explanation of these faculties and how they generate an error.
The faculty of cognition simply refers to our capacity to have ideas in our minds. As Descartes puts it this faculty "neither affirms nor denies anything but merely apprehend[s] the ideas regarding which I may form a judgment." You can think of this faculty as the ability to picture ideas in our mind, be they ideas of objects or concepts. This faculty is limited since we do not apprehend every idea that can be thought. However, it is not its limit that causes our errors. After all, there is no reason to think that God should have given us an infinite faculty of cognition. So this limit is not due to a lack of something we should have. In Descartes’ words, we do not lack knowledge as a privation but merely a negation. Again he is speaking to an audience familiar with scholastic terminology. To lack something as privation is to lack something one is supposed to have whereas to lack something as a negation is simply to not have something. For example, the lack of the ability to see is shared by both a stone and a blind man. But they cannot see in different ways. After all, the blind man is supposed to be able to see (people are supposed to be able to see after all!) but the stone was never meant to see. So we say that the blind man lacks sight as a privation but the stone lacks it as a negation. Applied to our faculty of cognition its finite nature is merely a negation.
On the other hand, our faculty of will is infinite. Descartes says that if we examine it carefully we will find it to be "so great that I am unable to conceive the idea of another that shall be more and extended." Of course, God's faculty of will is "incomparably greater" than ours but this is due, in large part, to God's infinite knowledge. So as an infinite faculty our power of free choice cannot be the source of our error.
The source of our error can be found in the difference between the two faculties. Our faculty of cognition is finite but our faculty of will is infinite. Think of it this way. The faculty of cognition allows me to hold ideas in my mind. The faculty of will allows me to decide, or in Descartes' words to affirm or deny, whether those ideas are true or false. It goes without saying that if I know the ideas I apprehend in my mind I will be in a much better position to affirm or deny their truth. However, if I affirm or deny an idea without such knowledge my chances for error increase greatly. The thing is my affirming or denying (that is my power of free choice) is not constrained by my knowledge of an idea. That's what it means for the faculty of will to be infinite. So I can affirm or deny the truth of an idea without actually knowing whether it’s true or false. And that is the source of error. If you find this strange just think about this. I will give you a statement that you will understand (i.e. it will be in your faculty of cognition) though you may not know whether it’s true or false. Never mind that though I will then ask you to affirm or deny it. You will be able to do so without any trouble at all but since you don't know whether it’s true or false you will likely as not be in error about your judgment.
OK here goes. Soren Kierkegaard was an 18th-century Austrian philosopher. Now you should understand what that sentence says even if you're not quite sure whether it’s true or false. So it’s in your faculty of cognition; you apprehend it as an idea. Now make a judgment about it: true or false? If you don't know who Kierkegaard is you have a fifty-fifty chance of being correct. Those are not good odds and just prove the point Descartes is making. Our chance for error goes up if we make judgments that go beyond what we know of.
The moral of the story is that there are two ways to decrease our chance of making judgments in error. The first is to restrict our judgments to things we have a certain knowledge of. If we're not sure we should suspend judgment. The second is to increase our knowledge. The more we know the better our judgments will be. It must be true what Bacon said: "knowledge is power." Oh by the way Kierkegaard, was from Denmark and lived in the 19th century.
Meditation Five
Having discovered the source of error we can proceed to investigate the rest of the world; the existence of material things. But first, we need to make one small philosophical detour in Meditation Five. We need to consider the essence of material things. The reason for this is quite simple. As of now, we are still in doubt about the source of our ideas of material objects; they may be adventitious or they may be fictitious (remember what those words mean?). In any case, we are still contemplating the ideas. Now, if it turns out that the very concept of a material object is inherently contradictory then we need not wonder whether any such things exist because it will be impossible for them to exist. So if their essence is impossible so too their existence will be impossible.
By essence, Descartes means those attributes which you cannot help but think about when conceiving of any given object. Take a triangle, for instance. When you think of a triangle you quite naturally think of three sides and 180 degrees of angles. You can't help but think of these attributes. We have, in Descartes' words, a clear and distinct idea of these attributes being attached to the object "triangle." As he points out in paragraph 7 of the fifth meditation "whatever is clearly and distinctly known is true."
The interesting turn in Meditation Five occurs in paragraph 8 where Descartes says "if because I can draw from my thought the idea of an object, it follows that all I clearly and distinctly apprehend to pertain to this object, does in truth belong to it, may I not from this derive an argument for the existence of God?" That's right Descartes is going to give us another proof for the existence of God. Why? Many scholars have speculated on this and since Descartes does not tell us we may never know for sure. However, in a series of replies to objections that Descartes wrote he does give us a clue. While the first proof deals with the cause of the idea of God, this second proof allows us to focus more on the attributes of God. So it’s not that this proof provides stronger evidence or that this proof is meant to succeed where the other proof failed. They are simply providing different perspectives on the existence of God.
This proof also turns out to be simpler to relate to as well. We can state it as a three-stage argument (in logic these are called syllogisms). Premise one: God is a being who contains all perfections. Premise two: Existence is perfection. Conclusion: God must exist.
Many people find this proof very elegant in its simplicity but perhaps just as many find it deeply flawed. Since it is not our purpose here to deal with the philosophy of religion questions I will not go into too much detail but I will share one particular objection offered by Immanuel Kant.
The proof seems to hinge on the second premise that existence is perfection. But this can only be true (says Kant) if existence is some kind of attribute. This, however, seems to be untrue. Of course, existence appears to be an attribute. Consider the following sentences:
That table is red.
That table is.
They both appear grammatically similar and clearly, the first one is attributing red to the table. So "red" is an attribute. It seems as if the second one is doing the same thing but with existence. However, this is not what is going on. As Kant points out in his Critique of Pure Reason "being is not a real predicate." That is his way of saying existence is not an attribute. As Kant puts it "it is merely the positing of a thing, or certain determinations, as existing in themselves." It is simply a logical fallacy to go from the "logical possibility of concepts to the real possibility of objects." This is what Descartes seems to be doing.
To see the force of this objection consider the following example. Suppose I say "I hope to have a son someday." You certainly understand what this means and it’s not strange at all. Also if I were to say "I hope my future son likes to play golf" nothing strange seems to be going on there (unless you happen not to like golf!). But suppose I were to say "I hope my future son exists." What could this possibly mean? It seems very strange to say precisely because existence is not a real attribute. Of course, my future son will exist. That is if I have a son in the future his existence is implied. That's what Kant means by saying that being is "merely the positing of a thing."
Alas for us this is where we will have to leave things with God and essence and existence. Descartes' consideration of essence has been to establish that the essence of material things is comprehensible. And based on what we've said so far and, with a few additions in the sixth meditation, it will turn out to be perfectly comprehensible, thus opening the door for us to infer, actually deduce, the existence of material things. It is to this task that we will turn next.
Meditation Six
We can now proceed to the deduction of material things. As Descartes says in the first paragraph of the sixth meditation "I at least know with certainty that such things may exist." We know this because we have examined their essence and in the example of the triangle have discovered that there is nothing contradictory to lead us to suppose that these things cannot exist. But since essence is different from existence (except as in the case of God whose essence is to exist) we need to consider their existence separately.
Descartes begins by making a distinction between the imagination and what he calls pure intellect. In many cases, these faculties are used together but to show their difference he suggests that we conceive of a chiliogon which is a thousand-sided figure. While it is possible to conceive it, we cannot imagine it by which Descartes means to view it "with the eyes of my mind." Imagination requires a special separate faculty from thinking and this faculty is what gives us the clue to the deduction of material substance. The way he puts it is that "a special effort of mind is necessary to the act of imagination, which is not required to conceiving or understanding." This special faculty he refers to, in paragraph 10 as the "passive faculty of perception." Before getting to this Descartes provides us with a summary of the previous meditations in paragraphs 5 through 9.
In paragraph 10 Descartes clarifies what he means by the passive faculty of perception. There are many perceptions that we have that we are not choosing to have. The vast majority of our sense experiences are not of our choosing. For example, if you look out your window you have no choice but to see what is there. It’s not like you can make up your scene to view. So what could explain this fact? There are, in Descartes' view two possible explanations. 1. God is causing these scenes. That is, the scenes (the perceptions) are not really there but just put into our minds by God. 2. The external objects themselves are causing our perceptions of them. You may believe that there is a third option namely that we are creating the perceptions but remember they are passive; involuntary. If we were causing them you'd think we would have control over them. So of the two options above, we need to figure out which is the correct one. The first is a problem because it makes God a deceiver which we have established is impossible. So there is only one option left. It must be that the external objects themselves are causing our perceptions. Therefore, material things exist. This, then, is the deduction of material things.
So Descartes has deduced the existence of the self, God, and material things; in that order. And to come full circle we conclude with some considerations of the self more informed than when we began our investigation. In paragraph 12 Descartes says that "there is nothing which that nature teaches me more expressly or more sensibly than that I have a body." We alluded to this earlier that in Descartes' view we are not the same as our body. What we are can be described as a thinking thing; a thinking thing that has a body not a thinking thing that is a body. This is an important distinction and is a distinct element in Cartesian metaphysics. Descartes is a dualist which means he believes that there are two distinct substances in the world: mental substance (the mind) and physical substance (the body). They have fundamentally different attributes. The mind is characterized by the attribute of thought. The body is characterized by the attribute of extension; which is taking up space.
The next step is taken in paragraph 13 where Descartes says "nature likewise teaches me by these sensations of pain, hunger, thirst, etc., that I am not only lodged in my body as a pilot in a vessel, but that I am besides so intimately conjoined, and as it was intermixed with it, that my mind and body compose a certain unity.” Herein is perhaps Descartes' greatest contribution to modern philosophy; a problem! If mind and body are so radically different how can they compose a unity? Another way of thinking about this is as follows. Descartes claims that there is an interaction between mind and body. But, given their differences, how is this interaction possible? This is the mind-body problem. It has occupied philosophers ever since Descartes' time.
Mind-Body Problem
Descartes himself provides an answer that is nothing short of shocking in its inadequacy. This has led many scholars to speculate that Descartes never saw this for the problem it is. We will address his attempted solution and then consider some solutions offered by contemporaries of Descartes. Descartes points out, in paragraph 20, that the mind and body do not interact at every point in the body. The locus of interaction is in the brain. It is very important to remember that for Descartes the mind is NOT the brain. The mind is a non-physical substance whereas the brain is part of the body. So the mind and body interact in the brain. To be specific Descartes says that the location of this interaction is the pineal gland. There were two reasons for postulating this as the location. First, it is centrally located in the brain and the only part not divided into halves; like the two hemispheres of the brain. Second, it was anybody's guess what the pineal gland did at the time and so this is as good a job as any for it.
The problem with this answer, of course, is that it doesn't address the question of how the mind and body interact, but rather, where they interact. We are still left wondering how to explain interaction and this is where Descartes leaves it.
There are two ways to deal with the mind-body problem; that is, the problem of interaction. We can try to explain the interaction or we can simply deny that there is any interaction. Surprisingly enough, the latter has been the more common approach. The reason for this is understandable. Explaining exactly how mind and body interact turns out to be very difficult. It is much easier to simply deny interaction entirely since on this approach there is nothing left to explain. Well, nothing except why there appears to be interaction. Three of Descartes' contemporaries attempted to do this while still preserving dualism.
The first was a philosopher named Nicolas Malebranche. He agreed with Descartes' dualism of mind and matter. However, he denied that the two substances interacted. Granted, mind and body appear to interact but this appearance is misleading. The real story is much different; and much stranger. The mind and body operate according to two separate causal series. We are in control of our mental faculties and so have some control over the causes and effects of the mental. But when the mental "causes" the physical it is nothing more than an "occasional" cause. That is to say, it is not the direct cause of what happens in the body. Rather, it is the signal if you will for the cause to take effect. In this case, the ultimate cause is God. So on the occasion when I will act in a certain way God causes my body to so behave. I told you it was weird. But believe it or not Malebranche's philosophy was "a considerable success." So says the historian Frederich Coppleston in his definitive nine-volume history of philosophy. This success was due in large part to what occasionalism stood against; materialism and empiricism both of which were regarded as damaging to God and religious faith. Sometimes you have to pick the lesser of two evils!
Given our probable reluctance to accept occasionalism we can consider other options. A second attempt to deny interaction was proposed by the German philosopher Gottfried Leibniz. Like Malebranche and Descartes, Leibniz is a dualist so he believes in the fundamental difference between mind and matter. However, he denies the interaction. Again we are left with the task of explaining the apparent interaction of mind and body. To do so Leibniz suggests a metaphor. Consider two clocks exactly alike in every way. We wind them up and set them to the same time. Then we let them work. Do you imagine that they will keep the same time? Within reason of course let's not get too carried away. But yes, they will keep pretty much the same time. Is that because one clock is causing the other to keep the same time? Is there any interaction between the two clocks at all? Of course not. The only reason they seem to interact (i.e. keep the same time) is because they were started at the same time. It’s the same with the mind and body. Through what Leibniz terms a "pre-established harmony" the mind and body were set (as it were) to run in sync and do so. Not because of any interaction mind you, but because God set them up at the same time.
This idea also enjoyed quite a wide popularity, especially among the scientists of the day who were interested in mechanistic explanations but wanted to preserve a place for God in the grand scheme of things. In particular, Sir Isaac Newton used the clock analogy to explain the universe with God as the one who starts the clock and lets it go. This clock analogy was to appear again in 1804 when William Paley used it to prove the existence of God (more on this anon).
A third attempt to solve the problem of interaction was offered by the Dutch philosopher Baruch Spinoza. He is somewhat different from the previous philosophers in that he immediately disagrees with the Cartesian notion that they are two fundamentally different substances. Wrong says, Spinoza. Given the definition of substance as "that which is in itself and is conceived through itself" neither mind nor body is substance. There can be only one substance. However, this one substance has many attributes, two of which are thought (which characterizes mind) and extension (which characterizes body). Depending on which perspective you take you can perceive the one substance as having either one attribute or the other or some other attribute entirely. So this one substance can be seen from dual aspects. And this is what we refer to his theory as the dual-aspect theory. This can also be referred to as "property dualism" as opposed to "substance dualism." We say property dualism because Spinoza refers to the dual attributes (or properties) of thought and extension. Descartes, of course, is a substance dualist because he refers to two substances: mind and body. By now you've probably guessed what the one substance is in Spinoza's theory: God.
Aside from these three theories, each of which had strong advocates, there are two other possibilities for dealing with the problem of interaction. These may be termed even more radical than the previous three if you can believe that. What each of the previous theories has in common is their acceptance, in some form, of the basic principle of dualism. But we can also deal with the problem of interaction by denying dualism altogether. What we then end up with is an entirely new metaphysical theory: monism.
Monism is the view that everything is composed of one substance and has two versions. The first version of monism, which we will consider in more detail later in the book, is materialism. This view postulates that everything in the universe is composed solely of physical substance. So when we refer to the mind or soul we are NOT referring to a non-physical entity. The mind, if it exists at all, must be something physical (like the brain). A contemporary of Descartes named Thomas Hobbes advocated this idea. It is very popular in some scientific quarters even to this day.
The second version of monism postulates that everything in the universe is the product of mental substance. On this view, there is no physical substance at all, only minds and the ideas in them. This theory is called idealism and gained some popularity in the 18th century through the work of the Irish philosopher George Berkeley. One of the implications of this view is that for something to exist it must be perceived. In this respect, it bears quite a striking similarity to modern quantum physics and it was Werner Heisenberg who recognized this connection and ran with it. Given the applicability of both types of monism to contemporary science, it’s no small wonder that we're trying to find a way to unify disparate theories today! We'll deal with these issues later as well. Our next task (after taking an exam of course!) will be to look at more recent attempts to deal with the problem of dualism and the nature of the mind.