Descartes' efforts to find new foundations for human knowledge led him to make sharp distinctions between reason and revelation, philosophy and theology. For many, this makes Descartes the first truly modem philosopher. In his Meditations, Descartes proceeded by a method of radical doubt, putting into question all the beliefs he had previously considered true in search of a point at which he would find an idea he could not doubt. Famously, this point was the cogito, the "I think," which in turn, led Descartes to assert "I am, I exist." With this "clear and distinct idea" as a foundation, a starting point for all knowledge, Descartes then argued that we can know that God and the world exist.
Outline
I. Descartes is considered one of the first philosophers of the modern period, in large part because of his efforts to conceptualize new foundations for human knowledge.
A. He was writing in a context in which the question of authority had become sharper and sharper as the reliability of traditional forms of authority was eroded by religious conflict and skeptical questioning.
B. But even as he doubts everything, Descartes immediately notices that he is still thinking; thus, the method brings him to the conclusion "I think, therefore I am."
II. With this claim about his existence, Descartes makes not only a philosophical claim about knowledge—an epistemological claim—but also a crucial claim about himself as a human being, namely, that he is "nothing but a thinking thing."
A. Descartes sharply separates his clear and distinct idea of his own existence from his knowledge of everything else in the world, from all material reality, even the reality of the body,
B. Descartes thus develops an ideal of knowledge that is found only in the self-consciousness of oneself, not in conversation with others, nor in relations forged with others in community, nor in the authorities of tradition.
III. But Descartes does have a way of getting from this self-consciousness to God and the world.
A. He begins by arguing for the existence of God, picking up on a tradition of arguments for God's existence that goes back at least to St. Anselm in the 11* century.
B. Having ascertained that God exists, Descartes argues as follows: Given that God is supremely good, God, as creator, would not have created a being, like Descartes, with the faculty for judgment that, when used properly, could be in error about such matters as the existence of things outside himself.
C. At issue here is not whether Descartes' argument for the existence of God is persuasive—most philosophers have found it unpersuasive—but the kind of God Descartes is trying to prove.
D. Also at issue here is whether, in the end, his appeal to God does not undermine his claim that the "I am" is the starting point for knowledge because in order to argue for God's perfection and infinity, he acknowledges that "my perception of God is prior to my perception of myself."
Suggested Reading:
Descartes and Moriarty, Meditations on First Philosophy. Stout, The Flight from Authority.
Questions to Consider:
How does Descartes' "I think, therefore I am" reflect his basic epistemological viewpoint?
How does Descartes get from the knowledge that he exists to the knowledge that the world exists?
Lecture Five—Transcript
Descartes and Modern Philosophy
In the last lecture, I introduced Descartes and his project of using natural reason to prove the existence of God and the immortal soul. With Descartes—and in particular with the sharp distinction he makes between faith and reason—we come to the real starting-point of our exploration of faith and suspicion in the modem period. Although we'll see that Descartes is defending religion by means of reason, when he turns to the authority of reason, and so to philosophy in the modem sense, he creates a new framework— and later thinkers will use this framework to criticize religion using reason.
In this lecture, I want to continue the discussion of Descartes, exploring in some more detail his epistemology—that is, his theory of knowledge—and I want to explain how it helped to establish modern philosophy and modern discussions of God. So, recall Descartes is writing in the middle of the 17th century, in the midst of the Scientific Revolution and during the period of the religious wars and the social upheaval and conflict that followed the Reformation. Both the religious and social upheaval, the increasing success of the scientific methodologies and techniques, both of these raised difficult questions about the intellectual authorities that had dominated Western thinking for centuries.
The conflict between Protestants and Catholics, in particular, led people to wonder whether any of their doctrines or values could be held with real confidence—and so whether the authorities of scripture, or Church, or tradition could continue to serve as the basis for Western culture. Descartes is grappling with mis problem of authority and grappling with the problem of knowledge—and in doing so, he plays a crucial role in the founding of modem philosophy in at least two respects. He makes a sharp distinction, as we've seen, between philosophy and theology—between reasoning based in a universal natural reason—philosophy, and reasoning based in revelation from scripture or tradition—theology. This places him at the beginning of a process that over the next century will see philosophers embracing reason, as opposed to revelation or tradition, as the primary intellectual and cultural authority. But if mis distinction between reason and revelation is to be made, and if a new conception of a universal human reason is to function in this authoritative way, then thinkers such as Descartes had to consider carefully just what this reason is. How does it work? What kind of knowledge does it make possible? These kinds of questions— epistemological questions—will preoccupy philosophers for at least the next couple of centuries, and do so even today.
So, let's turn now to see how Descartes addresses these questions— keeping in mind, of course, that his solutions will not go unchallenged by the philosophers that follow him. I have already mentioned Descartes' important 1641 treatise entitled Meditations. I will return to this book shortly, but I want to begin with an earlier text, his Discourse on Method, which he published in 1637. Early in this book Descartes establishes the context for his project by reflecting on his education. He notes first that at an early age he had been introduced to the world of philosophy and theology and had been possessed of a tremendous desire to learn from previous thinkers. But he then says:
as soon as I completed this entire course of study, at the end of which one is ordinarily received into the ranks of the learned, I changed my mind entirely. For I was embarrassed by so many doubts and errors, which appeared in no way to profit me in my attempt at learning, except that more and more I discovered my ignorance.
So, from the start of his Discourse on Method, Descartes casts doubt on the intellectual authorities of the past. He separates himself from "the ranks of the learned" in a way not unlike the original figure of Western philosophy, Socrates, by suggesting that the more he tried to learn, the more he discovered his own ignorance. A few paragraphs after this passage, Descartes considers another type of knowledge, and in so doing employs a metaphor that will have a major impact on his epistemological project. Still reflecting on his past, he writes:
[He had taken] especially great pleasure in mathematics because of the certainty and the evidence of its arguments. But I did not yet notice its true usefulness and, thinking that it seemed useful only to the mechanical arts, I was astonished that, because its foundations were so solid and so firm, no one had built anything more noble upon them. On the other hand, I compared the writings of the ancient pagans who discuss morals to very proud and magnificent palaces that are built on nothing but sand and mud.
Again, Descartes is critical of the authorities of the past—which, in comparison with the solid foundations of mathematics, are creating structures of thought bound to collapse because they have been built on unstable ground. The implicit question, of course, is whether the kind of firm foundation that supports mathematics can be found for what he calls "more noble forms of knowledge." This is the project he sets for himself in the Discourse on Method and that he repeats and refines in the Meditations. In the Discourse, these reflections set the stage for one of the most famous scenes in modem philosophical literature:
I was in Germany then, where the wars—which are still continuing there—called me; and while I was returning to the army from the coronation of the emperor, the onset of winter held me up in quarters where, finding no conversation with which to be diverted and, fortunately, otherwise having no worries or passions which troubled me, I remained for a whole day by myself in a small stove-heated room, where I had complete leisure for communing with my thoughts.
With this, Descartes I think captures clearly and succinctly a perfect image of his time and his philosophy. When he talks about "the wars" he is talking about the Thirty Years War that would not be settled, as we have seen, until the Peace of Westphalia in 1648—one of the numerous wars of the time being fought over visions of God, salvation, and truth, among many other things. So, the scene opens with a dramatic contrast: Outside the religious wars are raging, while inside Descartes sits, a solitary figure without passion or anxiety, by the fire. This solitude is important, for having already told us about how he rejected the past learning of his youth, he goes on here to express the view that the products of human endeavor—whether building cities or constructing philosophical systems—are almost always better when they are the product of a single mind with a plan rather than the haphazard product of people building on the efforts of the past. To invoke again the image of foundations, Descartes is suggesting that if one is to build something solid, one has to raze the edifices of the past and start on new foundations, with a good plan.
As he proceeds along these lines, however, we see that not only does this razing of existing edifices lead him to reject his past learning, but—even more radically—it leads him to question all of his own beliefs. As he puts it, he needs to "reject as absolutely false everything in which I could imagine the least doubt, so as to see whether, after this process, anything in my set of beliefs remains that is entirely indubitable." This means, he goes on to say, that he must not accept
Anything as true that I did not know evidently to be so; that is, carefully to avoid precipitous judgment and prejudice; and to include nothing more in my judgments man what presented itself to my mind with such clarity and distinctness that I would have no occasion to put it in doubt.
In other words, the least doubt about anything is enough to disqualify a belief or a judgment
Descartes is looking for that which is indubitable—or, as he puts it in the passage I just read, ideas that are clear and distinct It's important to note that when Descartes talks about doubting beliefs or judgments, he is not just talking about abstract ideas or beliefs about, say, God or the meaning of life, but also about things as fundamental as the evidence of his own senses. As he'll put it a few years later when he writes the Meditations, when we dream we think we are sensing things that we really are not Maybe, he proposes, this is also true of our waking life, Maybe, he goes on to say, although he has believed all his life that there is a God who is good, perhaps, instead, there is—and here's another quote—"an evil genius, supremely powerful and clever, who has directed his entire effort at deceiving me. [Such that] I will regard the heavens, the air, the earth, colors, shapes, sounds and all external things as nothing but the bedeviling hoaxes of my dreams."
So, what we see here is that in an effort to find firm foundations for human knowledge, Descartes employs a method of radical doubt. He questions everything until something is so clear and so distinct that it can no longer be doubted. This thoroughgoing skepticism in the service of a new epistemology is one of Descartes' major contributions to modem philosophy. But this skepticism is not a principle of life; it's not a kind of spiritual practice, as it had been for the skeptics of ancient Greece. For Descartes, rather, this skepticism, this radical doubt, is a philosophical method in the service of epistemology. He's not trying to argue that experience really is a dream, that God really is an evil genius, or that we have no grounds for trusting the evidence of our senses. So, we shouldn't see him here as a kind of crazy philosopher—so removed in his abstractions that he forms ideas that can't possibly be true, that no sensible person would entertain, that could be of no use in everyday life. Rather, we need to consider him instead as a kind of scientist. He's in a lab, He's conducting an experiment. He is engaged in the close analysis of consciousness. He's trying to distinguish one class of ideas, or judgments, or perceptions, from another—and trying to get a clear sense of how we know and what we can know.
So, what are the results of this experiment, other than a lot of doubt? Descartes' famous answer is this:
I noticed that, during the time I wanted thus to think that everything was false, it was necessary that I, who thought must be something. And noticing this truth—I think, therefore I am—was so firm and so certain that the most extravagant suppositions of the skeptics were unable to shake it, I judged that I could accept it without scruple as the first principle of the philosophy I was seeking.
Descartes cannot doubt that he thinks, and if he is thinking, then he must exist "I think, therefore I am," or as he puts it in the Latin in which he first formulated it: "Cogito, ergo sum," and we'll come back to this concept of cogito in a minute. Although Descartes has gone so far as to doubt the existence of his own body, he believes that he cannot go so far as to doubt his own existence, because he cannot get beyond the idea that he is thinking—for even when he is doubting, or dreaming, or hallucinating, he is still thinking. Even the evil genius, he says: "will never bring it about that I am nothing so long as I shall think that I am something." For Descartes, this move provides him with a "clear and distinct idea," and so with the first principle for the foundation of his philosophy: He knows with absolute certainty that he thinks—and, therefore, that he exists.
I will follow many others in suggesting that with this statement—"I think, therefore I am"—Descartes initiates modem philosophy. Of course, after saying something like that, one immediately has to qualify it by saying mat other major philosophers of the time—and we could include here Thomas Hobbes, Baruch Spinoza, Gottfried Leibniz—all of these other philosophers also played major roles in the beginnings of modern philosophy. But Descartes is important not only because of his efforts to find secure foundations for our knowledge, but also because in making this effort he helps to create a new way of understanding human subjectivity, of thinking about what it is to be a human self. Through his process of doubting, Descartes comes to define the self in terms of thinking because this is clearly, for him, the most certain thing about the self and the manner in which it exists. So, he writes, "I am therefore precisely nothing but a thinking thing"—which is to say, he goes on, "a thing that doubts, understands, affirms, denies, wills, refuses, and that also imagines and senses." Philosophers often refer to this thing, this self, by borrowing from the Latin formulation of Descartes' famous line. They refer to it as the "cogito"—"I think." With Descartes formulation of 1he cogito, we stand at the origin of a modern conception of human subjectivity that has had enormous influence.
There are two things to point out here: First, for Descartes, what is true is not what God says, not what past authorities say, not what I discover in conversation with others, but what can be clear and distinct in my own mind—or as the philosopher Jeffrey Stout puts it: "what can be clear and distinct in the privacy of subjective illumination." Second, Descartes is sharply separating his clear and distinct idea of his own existence from his knowledge of everything else in the world—from all material reality, even the reality of his own body. The cogito is the primary reality. There are, then, for Descartes, two different orders of reality: the spiritual world of thinking and the physical world of nature and our bodies. So, I—as a self-conscious, thinking thing—am, in some crucial sense, separated from the world, from other human beings, from God, and from my own body. They are not immediately known to me in the way that I am known to myself.
So, Descartes has proved to his satisfaction that he exists—and that in this existence as a thinking thing, he has a clear and distinct idea that can serve as the basis for all other knowledge. But while he has proved his existence, he has done so in a way—by doubting all that exists outside the self, the cogito—that seems to effectively enclose the self in its own thinking. Then, the question, of course, is: Can he get outside of this thinking thing to other things? Can the knowledge he has founded be of any use if it can only prove the existence of the self and not the existence of things outside the self—things in the world or God?
These are questions that occupy Descartes in the latter parts of the Discourse on Method and the Meditations. Let me begin to get at this issue of God by returning to his Meditations and to his reflections on the possibility that an evil genius is deceiving him about everything.
He notes that now that he has a firm foundation in the cogito, he should inquire into whether he might be able to remove this ground for doubting the testimony of his senses. In doing so, Descartes not only gets rid of the evil genius, but proves, or so he claims, the existence of God. He does so in such a way that he can then argue that God allows him to claim knowledge about the world.
Before getting into the details of Descartes' argument for the existence of God, I should pause to note that this argument is important not just because of the role it plays in Descartes' work, but because with it Descartes takes yet another first step into modern philosophy by offering an argument for the existence of God that is basically completely detached from religious faith. As we saw in the letter that he writes to the Deans and Doctors in Paris, Descartes wants to be able to prove God solely through the use of natural reason. This is not at all to say that we don't find arguments for the existence of God before Descartes. Arguments of this sort go back at least to the Greek philosopher Aristotle, who argued for the existence of a first mover of all things, and to medieval Christian theologians, such as Anselm and Aquinas, and Jewish philosophers, such as Maimonides. In each of these thinkers, one can find variations on the arguments that we will see in Descartes and other modern philosophers. But it is crucial to understand that the way these so-called arguments tended to work in the medieval period is very different than the way they come to work in philosophers such as Descartes and those who follow him. Here we are back at the important distinction between theology and philosophy.
Descartes' argument has its origins in the work of Saint Anselm in the 11th century. Anselm gave one of the most influential and I think useful definitions of theology in his book called the Proslogian, written in 1077, when Anselm defined theology as "faith seeking understanding." We will return to this view of theology in later lectures, but here we need only to note the important point that in this view, theology begins in faith. One not only believes in God in the sense that one is committed to, trusts in, God, but in the sense that one believes that God exists. So, when Anselm develops what is called the "ontological argument for the existence of God"—and I will explain this phrase in just a minute—he's doing so not so much as a proof of the existence of God, but as a way to further his understanding of God, as a way of inquiring into what this God that I pray to, that I worship, is. Anselm, in the end, is more interested in elucidating the concept of God than in proving that God exists.
For Descartes, though, things are very different. Though he affirms his faith frequently in his writings, as we have seen, he is trying to show that he can establish the existence of God in a way that does not depend on faith—that makes use only of our natural reason. He is, in other words, offering one of if not the first arguments for the existence of God based solely on philosophical grounds. Again, this will be a project that other philosophers in the modern period will take up as well.
So how does Descartes go about proving the existence of God? Recall that his starting point is the cogito: He knows that he exists as a thinking thing. But then the question is whether there is anything other than that thinking thing that exists: Does anything that he perceives or conceives to be existing actually exist, or is it all some sort of dream? To tackle these questions, Descartes decides that he should begin by asking whether there is a God—and whether, if so, this God can possibly be a deceiver, like the evil genius.
He begins by identifying three premises. His first premise is that some ideas that he has, as he puts it, "contain more objective reality in them" than others—thus, as an example, he says the idea of substance has more objective reality than the idea of accidents. By "substance," Descartes is referring to the basic fact that something is, to the sheer thatness or stuffness of things in the world—that this podium is, for example. When he refers to accidents, he's referring to how something is, its qualities—so this podium is white and about four feet, three and a half feet high. So, the substance of a thing, according to Descartes, has more objective reality in it than its accidents. Then, Descartes takes us one step further, and he says that the idea of a supreme deity has more objective reality than ideas of finite substances. So, my idea of a supreme deity has more reality than this podium, than this stuffness, the substance of this podium. Descartes' second premise is that when one thing causes another, we must agree that there must be at least as much reality in the cause as in the effect His third premise gives us a sense of what he means when he uses this term "reality." He says that something less perfect cannot be the cause of something more perfect. So, reality, for Descartes, is a function of what he calls "perfection."
He begins his thinking about God with these claims about degrees of reality or perfection, and about causation. He believes that these claims follow logically—that they are part of the way we necessarily see the world. So again, to go back to Descartes' method of doubt: When thinking about the world or thinking about God, he had entertained the possibility that these things are not real—that he had been dreaming them, or that they had been implanted in him by an evil genius. In other words, that either he or the evil genius had been the cause of these ideas. But then, given what he has said about perfection, and causality, and reality, he needs to ask himself whether he or the evil genius could be the cause of the idea of God— that is, of the idea of a being, as he puts it, that is "infinite, independent, supremely intelligent and supremely powerful and that created me along with everything else that exists."
In short, he asks, could the idea of a perfect being have come from something that is less than perfect—that is, a finite being like himself or an evil being like the evil genius he had hypothesized? Given his premises about perfection and causation, his answer is no—if he can conceive of God, God must exist. Only something perfect could have been the cause of this idea of perfection. This is the basis of what philosophers call the "ontological argument." Ontology is the theory of being. Descartes is arguing that the only way one can conceive of a perfect being is that if one, in fact, exists. In other words, he is arguing from a conception or an idea to existence, or being.
He puts it this way: "The whole force of the argument consists in the fact that I recognize that it would be impossible for me to exist, being of such a nature as I am (namely, having in me the idea of God), unless God did in fact exist." I'm not going to evaluate the merits of this argument, except to say that many philosophers have found it unpersuasive—we will see one of these, Kant, in a couple of lectures—many of them because they claim that we simply cannot argue from an idea to reality in this way. But I do want to stress the following points. First, we should note the importance of this argument for Descartes' overall effort at proving not only that something other than he as a thinking being exists, namely God, but also for his efforts to establish the cogito as the foundation for all knowledge.
It would not do much good for him if, having proved mat his existence is certain, this knowledge would not ground any further knowledge. But once he proves the existence of God, he argues that he can also prove the existence of things in the world. Basically, his argument is that a perfect God would not deceive us, as an evil genius would, because "deception or trickery [is] always indicative of some imperfection." So, he is proving that a perfect being exists. This perfect being, because he is perfect, could not deceive him. Such a God would not create a being, like Descartes, with the faculty for judgment then when used properly could be in error about matters such as the existence of things outside of himself.
The second point to make here returns to. my earlier remarks on modem arguments for the existence of God. This is a God that in some sense resembles the God of the Bible—a powerful God that sustains, if not creates, existence of self and world, and a God that is good and perfect. But it's also a God that remains relatively abstract in its perfection. What, we might ask, is the relation of this God of the philosophers, a God proven by philosophers, and the God of the Bible, or the God of the Qu'ran, or the God worshiped by Jews, Christians, or Muslims? We'll return to mis question.
The final point to make is that it may be the case that Descartes' proof of God forces us to rethink his cogito, or at least to introduce some complications. As we've seen, Descartes founds his epistemology on the clear and distinct idea that he thinks—and only then, once he establishes the cogito, does he move on to the proof for the existence of God. His claim that he thinks and exists is the foundation for his argument for the existence of God. But note one of the passages I read a minute ago, where Descartes says that: "It would be impossible for me to exist... unless God did in fact exist." So, he seems to be suggesting something like this: Although his epistemological reflections have as their foundation the "I think," the cogito, which then makes it possible to think; and then God; and then, finally, the world—from a different perspective, God is, in fact, prior to Descartes; mat is, God's existence is prior to, and the cause of, Descartes' existence. He elaborates on this point in another passage. He writes: "I clearly understand that mere is more reality in an infinite substance than there is in a finite one. Thus the perception of the infinite is somehow prior in me to the perception of the finite, that is, my perception of God is prior to my perception of myself." So now it seems that we are not just talking about God's prior existence, but of my sense of mis existence. Some kind of perception of God is prior, according to Descartes, to my sense or my perception of myself. So again, even though Descartes grounds knowledge in his clear and distinct idea of his own thinking, and grounds his sense of his own existence in this idea of his own thinking, he also sees—clearly and distinctly—that the knowledge he has of himself is preceded by a perception of God, who makes his existence possible. So although his thinking of himself grounds his knowledge, he knows that God grounds his existence—and he knows again that there is some sort of perception, and it clearly doesn't count as knowledge, but it is some sort of perception—even grounds his own sense of himself.
In this lecture, we have seen some of the reasons why historians of philosophy often place Descartes at the very beginning of modern philosophy. He separates philosophy and theology and founds philosophy in natural reason. He articulates a dualistic view of the subject as a thinking thing—divorced, in some fundamental sense, from matter and body. He employs natural reason to prove the existence of God. In all of these ways, Descartes raises questions and gives answers that will be at the center of the West's philosophical agenda for centuries.
