Introduction: What is the philosophy of biology?

Philosophy, Aristotle wrote, begins with wonder. And, for a long time, philosophy meant the same thing as science. Indeed, in some universities, physics is still called “natural philosophy,” and philosophy is taught in the department of “moral science.” The reason is not hard to see. The history of Western philosophy is the history of a discipline that has been “spinning off” sciences since about 300 BC when Euclid wrote the Elements and established the separate discipline of mathematics. It was only much later, in the seventeenth century, that physics finally established itself as a discipline distinct from philosophy, followed in the late eighteenth century by chemistry, and, as we will argue in the next chapter, by biology as late as 1859, when Darwin published On the Origin of Species. This process continues, for there are other disciplines, still in the process of spinning themselves off from philosophy. As the sciences establish their separate existences, two questions arise: Do the sciences leave anything to philosophy when they “spin off,” and, if so, why do they leave unfinished business to philosophy? The answer to the first question is obvious. Each of the sciences leaves to philosophy issues that they might be expected to answer but have not. Consider the question of what a number is. A number is not after all a numeral, which is just the symbol we use to name a number. For “2,” “II,” “two,” “dos,” and “dho” all name the very same number, in Arabic, Roman, English, Spanish, and Hindi notation. We may hold, as many followers of Plato still do, that numbers are “abstract objects,” or that there are no such things and that numbers are mental constructs. But it will be in vain to look to mathematics for an answer to the question of what a number is. That question has remained one for philosophical inquiry since Plato. Or consider the question of what time is. Time is a variable in many of the most important physical laws. Newton’s second law, for example, tells us that force equals masssacceleration, F=ma, where acceleration is defined as the rate of change of velocity with respect to time, a=dv/dt. But the question of what is time, t in the equation, has remained unanswered in physics and left to philosophers.