Introduction

Every day, in newspapers all around the world, astrologers tell peo­ple what life has in store for them. Under each of the star signs, which go with birthdates, there is a short message telling, say, Taureans to take special care in financial matters or Librans to expect progress in affairs of the heart.

It is an important fact that this criticism is relatively modern. Until the seventeenth century most intellectuals in the West thought that there was something to astrology, and even those who did not believe in it would not have criticized it in this way. Of course, there is a simple enough reason for this. Science, in the modern sense, has only developed since the seventeenth century. As a result, in the philosophy of science—unlike philosophical psychol­ogy, epistemology and the philosophy of language—most of the problems are less than three centuries old.

Though criticism of theories as unscientific has become relatively familiar in the last three hundred years, it is not obvious what the force of this criticism is. If, after all, a particular astrologer often gets things right, people who read the horoscope might not care very much whether the predictions were scientific. What they want of astrological predictions is not that they should be scientific but that they should be true. My friend Peter, who believes that astrology works, worries more about the vagueness of predictions and about their accuracy; and Mary, who believes in them too, worries, because she is a Christian, about whether she ought to make use of them.

But people who criticize astrology as unscientific are not just say­ing that they don't believe these horoscopes, and they are not just saying that it is morally wrong to rely on them. Indeed, someone could criticize astrology as unscientific and still believe that a par­ticular astrologer was a reliable guide to stock market prices.

This question is one of the central problems of the philosophy of science, which I am going to discuss in this chapter. Indeed, it has received so much attention that it has a name. Karl Popper, one of the most influential philosophers of science of our century, has called this the “demarcation problem.” What is it that distin­guishes between science and nonscience? How are we to demarcate the boundary between them?

Though this is a central problem of the philosophy of science, there are many reasons why understanding the nature of science has been important to philosophers. Logic has led to new work in the sci­ences of mathematics and linguistics; and the philosophy of mind exists in intimate relation with the science of psychology. Functionalism was prompted by the development of computers and computer science. As we shall see at the end of the chapter, these are not the only places where the interests of scientists and philosophers overlap, and computer science, linguistics, mathematics, and psy­chology are not the only sciences that raise philosophical questions.

These philosophical issues about particular sciences are interest­ing and important. But there is a much more general reason why understanding science is important to philosophy. We saw in Chapter 2 that questions about what and how we know are a central philosophical concern. Philosophy has a general interest in science because science is an organized search for knowledge. After all, what better way to find out about knowledge than to examine the theories and institutions in our society that have made the greatest contribution to expanding our knowledge of the world?

4.2