Rene Descartes and the Enlightenment Search for a New Method of Thinking (1596-1650)

Outline of Lecture

I. Introduction
II. Rene Descartes' Life (1596-1650)
III. The Philosophical Problems He Sought to Solve
IV. Descartes' Method
V. An Outline of His Metaphysics
VI. David Hume (1711-1776), Critic of the Enlightenment

Introduction

Rene Descartes first defined the kind of thinking the Enlightenment believed it necessary to do to clear away the old foundations and build new ones. So in many ways his method of inquiry stated in his Discourse on Method became a vision for what might be achieved if mathematical thinking were applied to all knowledge and areas of human life. Despite the fact that he soon attracted critics who, using reason and analysis, raised serious questions about his conclusions, he still is the first important figure in showing the Second Europe how to proceed in defining itself as a new outlook. In this section, we want to look at the life and thought of Descartes as representative of the Enlightenment confidence in reason. Then we will look briefly at David Hume's response to Cartesian thought to show how the Enlightenment proceeded to question even its most basic assumptions. In other words, to show how rationalism goes on to question even rationalism, arriving at skepticism as another part of the Second Europe's outlook. This will serve to remind us that the Enlightenment was more complex than a single figure and set of ideas may first suggest. It can't be so neatly tied up so that you don't see a few strings sticking out here and there.

Rene Descartes' Life (1596-1650)

Rene Descartes was born in 1596 in Le Haye in western France to the family of a prosperous French lawyer. He received an excellent education for his time in mathematics, philosophy and science at the Jesuit college of La Fleche, one of the best schools in France. There he was profoundly touched by three influences, two intellectual, a third political. The first experience was the thrilling, and shocking, discovery of Galileo's work, The Starry Messenger (1610), which reported the existence of Jupiter's four moons. Was Ptolemy wrong and Copernicus right? Heretofore, it had been assumed, following Ptolemy, that the heavenly firmament was complete, perfect. If not, the implications were staggering. The passion ignited in young Descartes for astronomy and physics remained with him through his life, eventually leading him to propose a comprehensive theory of theoretical physics in Principles of Philosophy (1644). A second influence was Michel de Montaigne (1533-1592) whose Essays Descartes studied at La Fleche. One essay, "The Apology of Raimond Sebond," struck Descartes with particular force because of these lines: "unless some one thing is found of which we are completely certain, we can be certain about nothing." The political influence was the assassination of the King of France, Henri of Navarre, by a religious zealot. There is an interesting, and I think persuasive, argument that the event profoundly affected political history by removing the one figure who was fighting to prevent religious zealotry from destroying France and threatening to engulf all Europe. After Henri's death, tensions within France between Protestants and Catholics and between Protestant and Catholic nations escalated. The resulting Thirty Years War (1618-1648) devastated much of central Europe and lasted almost through Descartes' life. Henri's death, according to the argument, also profoundly affected Descartes who was so seared by the sectarianism of the age that he sought unassailable fundamental principles in a rational realm above and beyond that of religious convictions.

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1.There is a scholarly argument about whether ideas are conditioned by historical experience or have a life independent of time and place. Does the historical context shape how ideas develop, or occur to certain figures such as Descartes? Would he have been so determined to find one certain thing had he not lived through the unsettling times of the Thirty Years War?
2. Imagine the reaction if it were to be proven that life, similar to human, were discovered on another planet, or another galaxy. That helps us understand the reaction to Galileo's discovery of the moons of Jupiter. Your reaction?

After La Fleche, Descartes went on to study law at the University of Poitiers. Then he signed on as a volunteer in Dutch and German armies, as he said, to broaden his experience. Military life did not end his interest in philosophy and mathematics. But he was disenchanted with traditional scholastic learning (which was essentially memorizing and explaining Aristotle) and despaired of finding the one certain principle on which everything else could be based. In 1619 while stationed in Ulm, a southern German town he had what he described as a sudden intense "illumination", almost a religious experience, followed by three dreams, the last of which was that reason underlay all experience. Awaking, he saw that the universe was mathematically structured and that if he used a single method of reasoning he could understand all knowledge. The single method was to doubt everything except "clear and distinct" ideas and then to proceed from there. He soon gave up military life and, living on private means, traveled to Paris, and thence to Holland where he began to write. Starting with a determination not to accept anything as true unless he had a clear and distinct idea that it was true, he decided that his most clear and distinct idea was that he existed. Even if he doubted his existence, he knew he existed because he had to exist to be able to doubt his own existence. The work in which he outlined his thinking, Discourse on the Method of Rightly Conducting the Reason was published in 1637, followed by Geometry (1637), Meditations (1641) and Principles of Philosophy (1644). These works brought him fame and in 1650 he was invited to Stockholm to become the tutor of Queen Christina of Sweden, a woman of great qualities as well as eccentric personal habits. It was the death of him, literally. Her habit of rising early (5:00 am) to study ruined his health and caused his death in 1650. (A link to a picture of the skull which encased his unusually thoughtful brain.)

The Philosophical Problems He Sought to Solve

Descartes' Discourse on Method rises out of a profound appreciation for mathematics and mathematical certainty, and a desire to achieve the same certainty in philosophy and all other knowledge that he saw in mathematics. The problems he sought to solve in this work were threefold:

(1) to free philosophy and science from the heavy, deadening authority of Aristotle and of traditional Church teachings.

(2) to construct a philosophic system which would allow freewill for man and at the same time allow a place for God to act and achieve his will. (A daunting task when one considers the difficulty posed by intellectually giving both God and man the freedom to choose and act at the same time.)

(3) to create a mathematically certain system for explaining the world.

Descartes began with the conviction arising from his intellectual illumination of 1619 that the universe is mathematically structured and can be understood by reason. His approach is called deductive reasoning, as opposed to inductive reasoning. (In the first case one begins with one certain principle and proceeds to establish others which can also be proven to be true. In the second, one starts with a diversity of thoughts and moves to the certain principle. Descartes is the exemplar of the first type of thinking; Francis Bacon (1561-1626) of the second. Both were important in the success of the scientific method, and there is a case to be made that Bacon's stress on inductive reasoning was of equal weight in stimulating Enlightenment thought. However, he was a popularizer and not a philosopher or scientist of the rank of Descartes, so Bacon is not our concern here.) Descartes was convinced that all reality could be reasoned deductively to have certainty. But he rejected the great authority to whom everyone so far had appealed--Aristotle. Aristotle's view of reality was imprecise; his language lacked the precision and certainty that Descartes felt necessary. Sensory experience was unreliable; it too had to be discarded at first. So he proposed clearing the deck, so to speak, and attempting a totally new approach, based on a single solid, certain, truth. What was it?

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Before answering the question just posed, let me ask another: what role does the kind of experience Descartes had, an intuitive leap as it were, play in understanding a difficult problem? Have you had such an experience when trying to solve a knotty problem, and suddenly grasped, without fully knowing why, that an answer would lie in a certain direction?

His Method

Descartes in the Discourse posed two fundamental questions and then proposed a new method. The questions were: how will I know what is certain (absolutely true) when I confront it? And how will I use that truth to construct a new system which is also true, because based on an unassailable truth? The method he described in four rules in the Discourse:

(1) The first of these was to accept nothing as true which I did not clearly recognize to be so: that is to say, carefully to avoid precipitation and prejudice in judgments and to accept in them nothing more than what was presented to my mind so clearly and distinctly that I could have no occasion to doubt it.

(2) The second was to divide up each of the difficulties which I examined into as many parts as possible, and as seemed requisite in order that it might be resolved in the best manner possible.

(3) The third was to carry on my reflections in due order, commencing with objects that were the most simple and easy to understand, in order to rise little by little, or by degrees, to knowledge of the most complex, assuming an order, even if a fictitious one, among those which do not follow a natural sequence relatively to one another.

(4) The last was in all cases to make enumerations so complete and reviews so general that I should be certain of having omitted nothing.

Using this method, Descartes proceeded to step one, finding the one fundamental truth from which to begin. He started with his own "self". The one clear and distinct idea he possessed was that he existed. Even if he doubted his own existence, he did exist, because he had to exist to doubt his existence. And thus he said, even if I doubt my own existence, I am thinking when I doubt. "I think, therefore I am." His own statement is worth quoting:

I observed that, whilst I thus wished to think that all was false, it was absolutely necessary that I, who thus thought, should be somewhat; and as I observed that this truth, I think, therefore I am (COGITO ERGO SUM), was so certain and of such evidence that no ground of doubt, however extravagant, could be alleged by the skeptics capable of shaking it, I concluded that I might, without scruple, accept it as the first principle of the philosophy of which I was in search.

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1. "Clear and distinct ideas"? Is this natural to all?
2. Was Descartes too easily convinced of his one fundamental principle? That he had to exist to be able to doubt his own existence?

An Outline of His Metaphysics

How Descartes proceeded after his first truth to construct his metaphysical system was not interesting to Enlightenment thinkers. They were caught up in the excitement of the method he used and his confidence in reason. Only philosophers care about metaphysics, the sort of thinking one does when one speculates about first principles, and seeks to explain the nature of being or reality and the structure of the world. But for our purposes, namely showing his confidence in the mathematical structure of the universe, it is worth talking briefly about his metaphysics.

Proceeding with the same logical method, Descartes concluded that he could believe with certainty that this self was conscious, independent of its thoughts, and possessed free will. Furthermore, he could be rationally sure that God existed. Given that I exist, Descartes said, how do I explain that fact. I am unable to have created myself. And when I trace back my origins through other people and finally from nature itself, there has to be some final cause for me and everything else. That final cause is God. Another proof: I have a clear and distinct idea of a perfect being which must have come from a perfect being. Thus the perfect being, God, exists. Not only does God exist, but he is omniscient, omnipotent, pure goodness. He alone is self-dependent. Everything else depends on him for its existence. He created the world and human beings as independent of each other although harmonious with each other, and independent of divine control, thus giving to man free will. The universe operated like a machine, again for logical reasons. It would not be credible that God created a haphazard world order. As he said in another work, The Principles of Philosophy, God is unchanging in his nature and in his actions, insuring that nature is dependable and that its order is knowable scientifically:

From the fact that God is in no way subject to change and that he acts always in the same manner we can arrive at the knowledge of certain rules which I call the laws of nature.[1]

Descartes' interests extended beyond philosophy and mathematics. He made original contributions not only in those two fields but in physics and optics as well. One scholar said of him, "Descartes helped fix in men's minds the mechanical pattern of the invariable laws of nature and the supremacy of reason." [2] From him the Enlightenment got its confidence about the world and man's ability to comprehend it through scientific knowledge. As a writer in the Encyclopedia said, Newton described the land which Descartes discovered. But David Hume disagreed.

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Before Hume, however, another question for thought. Descartes placed a lot of confidence in rational thought. Too much?

David Hume (1711-1776), Critic of Cartesian Philosophy and the Enlightenment

Before you get carried away with the beauty of Descartes' thought, and assume everyone agreed with him, consider David Hume. Hume, a Scottish historian and philosopher, in Enquiry into Human Understanding (1748) maintained that knowledge came solely from sensory experience. Everything in the intellect was first in the senses. But these sensations were purely individual. What an individual perceived as objects were just that, perceptions. And even if you found some other person who agreed that the two of you were having the same perceptions, it did not matter because the "other person" was only a perception. If one followed Hume, and it has been hard to ignore him since the Enquiry, then you would say that Descartes too easily convinced himself that he was having "clear and distinct" ideas. God, according to Hume, is "entirely beyond the reach of human experience." So is the premise that nature is governed by a rational order which can be understood by one thinking rationally because that too is beyond the reach of human experience. Science is no more soundly based than any other kind of inquiry, because it assumes a premise which cannot be verified from experience. And so Hume was a critic of the Enlightenment when he said the mind or reason was not capable of knowing all things. And his critique of rationalism was one of the early assaults on the bright hopes and confident expectations of the Second Europe.

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Let's take up Hume's ideas in order. Is he right?