Rene Descartes (1596–1650) was a seminal figure in the scientific revolution of the 17th century. This was a revolution in the full sense of that word: an old worldview was overturned and rejected in favor of a new, very different worldview. This new worldview was based on hypothesis and experiment, on reducing scientific phenomena to a very few, simple mathematical formulae. The old worldview was Aristotelian scholasticism: a worldview closely tied to the Catholic Church, which had been the exclusive seat of learning in the West since the fall of the Roman Empire. The Aristotelian worldview was based on reason and logical deduction. Truth was something that could be known with certainty and deduced from other self-evident truths.
The old worldview of Aristotelian scholasticism was not going to go down without a fight. Many of the advocates of the new science—Descartes and Galileo being two notable cases—still used much of the language and terminology of the Catholic academics. When they tried to work against this system, the church would often come down hard: in 1633, the Inquisition condemned Galileo's theories—in particular his theory that the earth revolves around the sun—and placed him under house arrest. This was the same year that Descartes completed The World, a lengthy discussion of his scientific views that were not altogether out of sympathy with Galileo's. Descartes was preparing it for publication, when, upon discovering that Galileo had been condemned, Descartes hastily suppressed his manuscript.
Though he dedicated his entire adult life to research in philosophy, mathematics, and science, Descartes did not publish anything until he was forty years old, largely due to his fears of censure. His first publication, in 1636, was the Discourse on the Method along with three scientific essays, one on optics, one on meteorology, and one on geometry.
The Discourse itself is meant to serve as a preface for these three essays, but it has since far surpassed them in reputation. While the essays are now rarely read, the Discourse itself has endured. The Discourse is intended to introduce the scientific method that Descartes has invented and to explain how his views came about and why he has been so hesitant to publish them, while the essays are meant to serve as evidence of the fruits of his labor. The Discourse does not just give us insight into Descartes's philosophy and his method; it also gives us insight into the intellectual climate of his day.
Explain the distinction between Aristotelian scientific method and the new science that Descartes and others replaced it with.
Aristotelian science is based on a method of demonstration and syllogism. It proceeds from first principles that are assumed to be certain, and from these first principles it logically deduces other results that are, in turn, treated as certain. The criteria for certainty are not very high, and the logical deductions are often quite faulty. Therefore, Aristotelian science embarrasses itself by making a number of grave errors. The new scientific method is based on a system of hypothesis and experiment. Theories are not taken as certain, just probable, and they are rendered increasingly probable the more experiential evidence there is to confirm them. Descartes is only part of the way into this new worldview. Most of his scientific inquiries follow this model, but he still feels it important to claim to have first principles that these scientific results follow from logically, and he feels it important to argue that these principles are absolutely certain.
Why did Descartes find his education unsatisfying? How does this dissatisfaction reflect his philosophy? (Hint: What had he been told he would gain from his education?)
Descartes had been brought up in an educational method that claimed it would teach him everything he needed to know in order to pursue knowledge and get by in the world. Having completed his Jesuit education, Descartes found that he knew everything his teachers wanted to teach him, but that he was far from satisfied with the knowledge it gave him. In particular, he felt he had no grounds for having any certainty with regard to what he had learnt. Descartes's philosophy is, to a large extent, motivated by a desire to find certainty. This leads him to reject all the precepts and principles of Aristotelian philosophy as not good enough, and to employ skeptical doubt in his search for a more solid foundation for knowledge.
What are the four rules Descartes uses to guide his inquiry when he decides to abandon all his former opinions? What biases are implicit in these rules? How do they affect his later conclusions?
The four principles are: (1) Not to accept anything as true unless it is evident, (2) to break problems down into parts and to work on the parts individually, (3) to start with the easiest knowledge and build toward more difficult matters, and (4) always to check over work and be wary of any errors. These principles are supportive of a foundationalist epistemology, which begins with certain simple, self-evident truths, and builds upon them. Descartes seems to assume that knowledge can be analyzed into parts and then built up from simple foundations. These assumptions lead him to believe that there must be certain self-evident first principles upon which all his philosophy can rest, and that all his subsequent conclusions can follow from these first principles.
What is analytic geometry? How does Descartes's method contribute to his discovery of analytic geometry?
What is the significance of Descartes claim, "I am thinking, therefore I exist"? How does he argue for that claim?
What are Descartes's two proofs of God's existence? What are the differences between them? Is one better than the other? Do you find them satisfying?
Why does Descartes present his physical theories as an imaginary hypothesis? Does this hurt their plausibility?
Explain the difference between a Cartesian physics based on a definition of matter and a Newtonian physics based on a definition of force. Which is more successful and why?
What reasons does Descartes give for not making the principles of his physics public? What do you think are the real reasons?
To what extent do Descartes's writings reflect the medieval tradition in which he was educated, and to what extent do they reflect a new, scientific worldview?