Ian Hacking, on the first page of the monumental "Experimentation and Scientific Realism":
Experiments, the philosophers say, are of value only when they test theory. . . So we lack even a terminology to describe the many varied roles of experiment. (Hacking 1982, p. 71)And Allan Franklin, on the first page of his Selectivity and Discord:
Experiment plays many roles in science. One of its important roles is to test theories and provide the basis for scientific knowledge. It can also call for a new theory. . . Experiment can provide hints about the structure or mathematical form of a theory, and it can provide evidence for the existence of the entities involved in our theory. . . it may also have a life of its own, independent of theory: Scientists may investigate a phenomenon just because it looks interesting. Such experiments may provide evidence for future theories to explain. (Franklin 2002, p. 1)It is a nice surprise to find myself in such good company. The aim of my paper, of course, is to try to provide a coherent picture of and some terminology for the various roles of evidence. One of the points that I make in the paper, which I'm not sure Hacking or Franklin would accept, is that there is a useful (functional) distinction to be drawn between observational and experimental evidence. I suspect they might even say that I leave some roles out of my picture.