The Philosophy Book

by DK Publishing

  This axiom—“I am, I exist” –forms Descartes’ First Certainty. In his earlier work, the Discourse on the Method, he presented it as: “I think therefore I am”, but he abandoned this wording when he wrote the Meditations, as the inclusion of “therefore” makes the statement read like a premise and conclusion. Descartes wants the reader—the meditating “I”—to realize that as soon as I consider the fact that I exist, I know it to be true. This truth is instantly grasped. The realization that I exist is a direct intuition, not the conclusion of an argument.

  Despite Descartes’ move to a clearer expression of his position, the earlier formulation was so catchy that it stuck in people’s minds, and to this day the First Certainty is generally known as “the cogito”, from the Latin cogito ergo sum, meaning “I think therefore I am.” St. Augustine of Hippo had used a very similar argument in The City of God, when he said: “For if I am mistaken, I exist”; meaning that if he did not exist, he could not be mistaken. Augustine, however, made little use of this in his thinking, and certainly did not reach it in the way that Descartes did.

  What use, though, is a single belief? The simplest logical argument is a syllogism, which has two premises and a conclusion—such as: all birds have wings; a robin is a bird; therefore all robins have wings. We surely cannot get anywhere from the starting point of just one true belief. But Descartes was not looking to reach these kinds of conclusions from his First Certainty. As he explained: “Archimedes used to demand just one firm and immovable point in order to shift the entire Earth.” For Descartes, the certainty of his own existence gives him the equivalent; it saves him from that whirlpool of doubt, gives him a firm foothold, and so allows him to start on the journey back from skepticism to knowledge. It is crucial to his project of enquiry, but it is not the foundation of his epistemology.

  "I shall suppose that some malicious demon of the utmost power and cunning has employed all his energies in order to deceive me."

  René Descartes

  What is this “I”?

  Despite the fact that the First Certainty’s main function is to provide a firm footing for knowledge, Descartes realizes that we might also be able to gain knowledge from the certainty itself. This is because the knowledge that I am thinking is bound up with the knowledge of my existence. So “thinking” is also something that I cannot rationally doubt, for doubting is a kind of thinking, so to doubt that I am thinking is to be thinking. As Descartes now knows that he exists and that he is thinking, then he—and every other meditator—also knows that he is a thinking thing.

  Descartes makes clear, though, that this is as far as he can reason from the First Certainty. He is certainly not entitled to say that he is only a thinking thing—a mind—as he has no way of knowing what more he might be. He might be a physical thing that also has the ability to think, or he might be something else, something that he has not even conceived yet. The point is that at this stage of his meditations he knows only that he is a thinking thing; as he puts it, he knows only that he is, “in the strict sense only” a thinking thing. Later, in the sixth book of the Meditations, Descartes presents an argument that mind and body are different sorts of thing—that they are distinct substances—but he is not yet in a position to do so.

  The only question that Descartes is definitely able to answer using his method of doubt is whether he is thinking. He cannot prove the existence of his body or of the external world.

  "This proposition, I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind."

  René Descartes

  Doubting Descartes

  This First Certainty has been the target of criticism from many writers who hold that Descartes’ approach to skepticism is doomed from the start. One of the main arguments against it takes issue with the very use of the term “I” in “I am, I exist.” Although Descartes cannot be wrong in saying that thinking is occurring, how does he know that there is “a thinker”—a single, unified consciousness doing that thinking? What gives him the right to assert the existence of anything beyond the thoughts? On the other hand, can we make sense of the notion of thoughts floating around without a thinker?

  It is difficult to imagine detached, coherent thoughts, and Descartes argues that it is impossible to conceive of such a state of affairs. However, if one were to disagree, and believe that a world of thoughts with no thinkers is genuinely possible, Descartes would not be entitled to the belief that he exists, and would thus fail to reach his First Certainty. The existence of thoughts would not give him the solid ground he needed.

  The problem with this notion of thoughts floating around with no thinker is that reasoning would be impossible. In order to reason, it is necessary to relate ideas in a particular way. For example, if Patrick has the thought “all men are mortal” and Patricia has the thought “Socrates is a man”, neither can conclude anything. But if Paula has both thoughts, she can conclude that “Socrates is mortal.” Merely having the thoughts “all men are mortal” and “Socrates is a man” floating around is like two separate people having them; in order for reason to be possible we need to make these thoughts relative to one another, to link them in the right way. It turns out that making thoughts relative to anything other than a thinker (for example, to a place or to a time) fails to do the job. And since reasoning is possible, Descartes can conclude that there is a thinker.

  Some modern philosophers have denied that Descartes’ certainty of his own existence can do the job he requires of it; they argue that “I exist” has no content, as it merely refers to its subject but says nothing meaningful or important about it; it is simply pointing at the subject. For this reason nothing can follow from it, and Descartes’ project fails at the beginning. This seems to miss Descartes’ point; as we have seen, he does not use the First Certainty as a premise from which to derive further knowledge—all he needs is that there be a self for him to point to. So even if “I exist” only succeeds in pointing to the meditator, then he has an escape from the whirlpool of doubt.

  "When someone says ‘I am thinking, therefore I am’, he recognizes it as something self-evident by a simple intuition of the mind."

  René Descartes

  An unreal thinker

  For those who have misunderstood Descartes to have been offering an argument from the fact of his thinking to the fact of his existence, we can point out that the First Certainty is a direct intuition, not a logical argument. Why, though, would it be a problem if Descartes had been offering an argument?

  As it stands, the apparent inference “I am thinking, therefore I exist” is missing a major premise; that is, in order for the argument to work it needs another premise, such as “anything that is thinking exists.” Sometimes an obvious premise is not actually stated in an argument, in which case it is known as a suppressed premise. But some of Descartes’ critics complain that this suppressed premise is not at all obvious. For example, Hamlet, in Shakespeare’s play, thought a great deal, but it is also clearly true that he did not exist; so it is not true that anything that thinks exists.

  We might say that in so far as Hamlet thought, he thought in the fictional world of a play, but he also existed in that fictional world; in so far as he did not exist, he did not exist in the real world. His “reality” and thinking are linked to the same world. But Descartes’ critics might respond that that is precisely the point: knowing that someone called Hamlet was thinking—and no more than this—does not assure us that this person exists in the real world; for that, we should have to know that he was thinking in the real
world. Knowing that something or someone—like Descartes—is thinking, is not enough to prove their reality in this world.

  The answer to this dilemma lies in the first-person nature of the Meditations, and the reasons for Descartes’ use of the “I” throughout now becomes clear. Because while I might be unsure whether Hamlet was thinking, and therefore existed, in a fictional world or the real world, I cannot be unsure about myself.

  "We ought to enquire as to what sort of knowledge human reason is capable of attaining, before we set about acquiring knowledge of things in particular."

  René Descartes

  Modern philosophy

  In the “Preface to the Reader” of the Meditations, Descartes accurately predicted that many readers would approach his work in such a way that most would “not bother to grasp the proper order of my arguments and the connection between them, but merely try to carp at individual sentences, as is the fashion.” On the other hand, he also wrote that “I do not expect any popular approval, or indeed any wide audience”, and in this he was much mistaken. He is often described as the father of modern philosophy. He sought to give philosophy the certainty of mathematics without recourse to any kind of dogma or authority, and to establish a firm, rational foundation for knowledge. He is also well known for proposing that the mind and the body are two distinct substances—one material (the body) and the other immaterial (the mind)—which are nonetheless capable of interaction. This famous distinction, which he explains in the Sixth Meditation, became known as Cartesian dualism.

  However, it is the rigor of Descartes’ thought and his rejection of any reliance on authority that are perhaps his most important legacy. The centuries after his death were dominated by philosophers who either developed his ideas or those who took as their main task the refutation of his thoughts, such as Thomas Hobbes, Benedictus Spinoza, and Gottfried Leibniz.

  The separation of mind and body theorized by Descartes leaves open the following question: since all we can see of ourselves is our bodies, how could we prove that a robot is not conscious?

  RENÉ DESCARTES

  René Descartes was born near Tours, France, and was educated at the Jesuit Collège Royale, in La Flèche. Due to ill-health, he was allowed to stay in bed until late in the mornings, and he formed the habit of meditating. From the age of 16 he concentrated on studying mathematics, breaking off his studies for four years to volunteer as a soldier in Europe’s Thirty Years War. During this time he found his philosophical calling, and after leaving the army, he settled first in Paris and then in the Netherlands, where he spent most of the rest of his life. In 1649 he was invited to Sweden by Queen Christina to discuss philosophy; he was expected to get up very early, much against his normal practice. He believed that this new regime—and the Swedish climate—caused him to contract pneumonia, of which he died a year later.

  Key works

  1637 Discourse on the Method

  1641 Meditations on First Philosophy

  1644 Principles of Philosophy

  1662 De Homine Fuguris

  See also: Aristotle • St. Augustine of Hippo • Thomas Hobbes • Blaise Pascal • Benedictus Spinoza • John Locke • Gottfried Leibniz • Immanuel Kant

  IN CONTEXT

  BRANCH

  Epistemology

  APPROACH

  Epistemology

  BEFORE

  c.350 BCE Aristotle says that “imagination is the process by which we say that an image is presented to us,” and that “the soul never thinks without a mental image.”

  1641 René Descartes claims that the philosopher must train his imagination for the sake of gaining knowledge.

  AFTER

  1740 In his Treatise of Human Nature, David Hume argues that “nothing we imagine is absolutely impossible.”

  1787 Immanuel Kant claims that we synthesize the incoherent messages from our senses into images, and then into concepts, using the imagination.

  Pascal’s best-known book, Pensées, is not primarily a philosophical work. Rather, it is a compilation of fragments from his notes for a projected book on Christian theology. His ideas were aimed primarily at what he called libertins—ex-Catholics who had left religion as a result of the sort of free thinking encouraged by skeptical writers such as Montaigne. In one of the longer fragments, Pascal discusses imagination. He offers little or no argument for his claims, being concerned merely to set down his thoughts on the matter.

  Pascal’s point is that imagination is the most powerful force in human beings, and one of our chief sources of error. Imagination, he says, causes us to trust people despite what reason tells us. For example, because lawyers and doctors dress up in special clothes, we tend to trust them more. Conversely, we pay less attention to someone who looks shabby or odd, even if he is talking good sense.

  What makes things worse is that, though it usually leads to falsehood, imagination occasionally leads to truth; if it were always false, then we could use it as a source of certainty by simply accepting its negation.

  After presenting the case against imagination in some detail, Pascal suddenly ends his discussion of it by writing: “Imagination decides everything: it produces beauty, justice, and happiness, which is the greatest thing in the world.” Out of context, it might seem that he is praising imagination, but we can see from what preceded this passage that his intention is very different. As imagination usually leads to error, then the beauty, justice, and happiness that it produces will usually be false. In the wider context of a work of Christian theology, and especially in light of Pascal’s emphasis on the use of reason to bring people to religious belief, we can see that his aim is to show the libertins that the life of pleasure that they have chosen is not what they think it is. Although they believe that they have chosen the path of reason, they have in fact been misled by the power of the imagination.

  "Man is but a reed, the weakest nature; yet he is a thinking reed."

  Blaise Pascal

  Pascal’s Wager

  This view is relevant to one of the most complete notes in the Pensées, the famous argument known as Pascal’s Wager. The wager was designed to give the libertins a reason to return to the Church, and it is a good example of “voluntarism”, the idea that belief is a matter of decision. Pascal accepts that it is not possible to give good rational grounds for religious belief, but tries to offer rational grounds for wanting to have such beliefs. These consist of weighing up the possible profit and loss of making a bet on the existence of God. Pascal argues that betting that God does not exist risks losing a great deal (infinite happiness in Heaven), while only gaining a little (a finite sense of independence in this world)—but betting that God exists risks little while gaining a great deal. It is more rational, on this basis, to believe in God.

  According to Pascal, we are constantly tricked by the imagination into making the wrong judgments—including judgements about people based on how they are dressed.

  BLAISE PASCAL

  Blaise Pascal was born in Clermont-Ferrand, France. He was the son of a government functionary who had a keen interest in science and mathematics and who educated Pascal and his two sisters. Pascal published his first mathematical paper at the age of 16, and had invented the first digital calculator by the time he was 18. He also corresponded with the famous mathematician Pierre Fermat, with whom he laid the foundations of probability theory.

  Pascal underwent two religious conversions, first to Jansenism (an approach to Christian teaching that was later declared heretical), and then to Christianity proper. This led him to abandon his mathematical and scientific work in favor of religious
writings, including the Pensées. In 1660–62 he instituted the world’s first public transport service, giving all profits to the poor, despite suffering from severe ill health from the 1650s until his death in 1662.

  Key works

  1657 Lettres Provinciales

  1670 Pensées

  See also: Aristotle • Michel de Montaigne • René Descartes • David Hume • Immanuel Kant

  IN CONTEXT

  BRANCH

  Metaphysics

  APPROACH

  Epistemology

  BEFORE

  c.1190 Jewish philosopher Moses Maimonides invents a demythologized version of religion which later inspires Spinoza.

  16th century Italian scientist Giordano Bruno develops a form of pantheism.

  1641 René Descartes publishes his Meditations, another of Spinoza’s influences.

  AFTER

  Late 20th century Philosophers Stuart Hampshire, Donald Davidson, and Thomas Nagel all develop approaches to the philosophy of mind that have similarities to Spinoza’s monist thought.

  Like most philosophies of the 17th century, Spinoza’s philosophical system has the notion of “substance” at its heart. This concept can be traced back to Aristotle, who asked “What is it about an object that stays the same when it undergoes change?” Wax, for example, can melt and change its shape, size, color, smell, and texture, and yet still remain “wax”, prompting the question: what are we referring to when we speak of “the wax”? Since it can change in every way that we can perceive, the wax must also be something beyond its perceptible properties, and for Aristotle this unchanging thing is the wax’s “substance.” More generally, substance is anything that has properties—or that which underlies the world of appearance.