Van Fraassen's Instrumentalism

Abstract

In The Scientific Image [1980], Bas van Fraassen argues against a particular form of scientific realism and for a view of his own which he dubs constructive empiricism. The version of realism he intends to refute is the view that the aim of science is to construct theories that are literally true, and that to accept a scientific theory is to believe that it is literally true (or at least approximately true). In contrast, according to van Fraassen's constructive empiricism, science aims only at theories that are empirically adequate, that is, at theories that accord with all observable events, and to accept a scientific theory is only to believe that it is empirically adequate. To accept a scientific theory it is not necessary, according to constructive empiricism, to believe what it says about unobservable entities, such as electrons. It is quite clear that van Fraassen is not merely advancing a thesis about actual scientific practice. He is not saying merely that science, as we know it, does not aim to discover true theories about unobservable events and processes, but rather that the discovery of such theories can never be the object of any reasonable human endeavour. The problem is not simply that we know, from the historical frequency with which theories are refuted, that the achievement of this aim is a practical impossibility. After all, if the frequency of empirical refutation counts against the aim of arriving at true theories, then it also counts against the aim of obtaining theories that are empirically adequate! Consequently, van Fraassen's objection is quite different from that of Laudan [1981], which is based on the historical frequency of theoretical errors.1 Instead, van Fraassen is claiming that it is not even possible to approach