Description and prescription
As we saw in earlier chapters, philosophers do not only try to understand concepts and theories, they also criticize many of our ordinary beliefs.
Skeptics, for example, challenge our ordinary claims to knowledge, arguing that we know much less than we think, and Wittgenstein and the behaviorists challenged our ordinary unreflec- tive belief that we might have Hobbesian “twinges.” Philosophers not only try to understand what we do believe, but also argue about what we should believe. As I said in Chapter 2, claims about what we should say, think, or do are prescriptive: they prescribe courses of thought and action. In the philosophy of science too, description and prescription go hand in hand.But in the philosophy of science, unlike the philosophy of mind or epistemology or the philosophy of language, the object of study is an institution—science—that developed in particular societies in the relatively recent past. All human societies have had minds and knowledge and languages, yet only recently have most societies come to have science. For this reason the descriptive task of trying to say what science is like is one that philosophers share with historians and sociologists of science. As philosophers, however, we want to ask the epistemological question whether science really does provide us with the knowledge it seems to, to address the prescriptive question whether we should accept some or any of the claims of scientific theories. If we do accept them, especially those that challenge our commonsense beliefs, then we want to have a proper understanding of them and to investigate their significance. But in order to make this sort of philosophical assessment of science, we must first try to see what it is really like.
This is why the philosophy of science and the history of science are often studied together—indeed, many universities have programs or departments of the history and philosophy of science, where the two kinds of study are carried out together.
If we look at science in this historical way, we can ask both, descriptively, how scientists construct their theories and, prescriptively, how they should create theories and find evidence that supports them. Because this approach looks at the development of science through time, we can call it a “diachronic” approach.Philosophers of science also discuss questions that have to do not with the way science develops but with the theories of science at a particular stage in its development. On this approach, we ask, descriptively, about the structure of scientific theories and what they say about the world and, prescriptively, about what justifies our belief in them. This way of studying science we can call “synchronic”; it has to do with issues about the state of science at a particular time.
The logical positivists made an important distinction that runs in parallel with the distinction between diachronic and synchronic questions. Some issues, they said, have to do with the context of discovery. These are questions about how to set about deepening our scientific understanding of the world. Thus, questions about how we should design experiments—questions of experimental methodology—belong to the context of discovery. But there are other questions that arise, which have to do with how we organize the evidence, the data we collect from experiment and observation, in order to decide whether it supports our theories. The issue here is not how we develop our theories but how we defend and justify them, and such questions are said to belong to the context of justification.
We should not assume in advance that the answer to the demarcation problem will have to do only with synchronic matters or only with diachronic ones: it might require considerations of either or both kinds. Nor should we assume at the start that what makes a theory scientific is either how you set about developing it or how you justify it: perhaps solving the demarcation problem will involve considerations about both the context of discovery and the context of justification.
I didn't set out to introduce you to philosophy by trying to define “philosophy.” And I'm not going to begin discussing science by trying to define “science” either.
Rather, I want to begin by discussing some of the distinguishing features of scientific theories. This is most easily done in terms of a specific example. So I shall start out with a simplified example of a scientific theory with which you may already be familiar. When we have spent some time discussing some of the characteristics of scientific theory, we shall be in a better position to return to the demarcation problem.4.3