Abstract

The choice between realism and instrumentalism is at the core of concerns about how our scientific models relate to reality: Do our models aim to be literally true descriptions of reality, or is their role only as useful instruments for generating predictions? Realism about X, roughly speaking, is the claim that X exists and has its nature independent of our interests, attitudes, and beliefs. An instrumentalist about X denies this. She claims that talk of X should be understood as no more than a useful locution for generating predictions, such talk should not be understood as taking on a commitment to the existence of X. According to an instrumentalist, we should either flatly not believe that X is out there, or else suspend judgement about the existence of X. The most we need acknowledge is that talk of X is useful in making predictions. The question of realism vs. instrumentalism can be asked about almost any theoretical entity in science. It is likely, and seems reasonable, that different answers will be given in different cases. Someone may wish to be a realist about certain theoretical entities (e.g. electrons), but an instrumentalist about others (e.g. centres of gravity). Not every noun-phrase in a scientific theory should be taken as expressing an ontological commitment. Psychological theories are no exception. Almost every theoretical posit in psychology has been questioned as to whether it is really out there or just a useful theoretical fiction. In this entry, I will focus on two major theoretical posits in psychology: (a) propositional attitudes (e.g. beliefs, desires) and (b) conscious states (qualia).