ABSTRACT
Empiricism is an ism with many meanings. In accounts of the history of philosophy, empiricism is often contrasted with rationalism, though serious historians frequently look with jaundiced eye at this way of telling the story (van Fraassen 2002). According to this formula, empiricists emphasize the role of sense experience, rationalists the role of reason. Each position can be given extreme formulations, as in the clashing claims that sense experience is the only source of knowledge or that reason is, and each position can be moderated, with the attendant possibility that they no longer conflict. The debate was usually framed in terms of the existence of “innate ideas” and often blurred the distinction between psychological and epistemological questions. A different kind of empiricism has been central to philosophy of science. Here empiricism contrasts with scientific realism, not with rationalism. When Galileo found himself in conflict with the Church, the philosophical issue concerned how heliocentrism should be interpreted. Galileo’s interrogator, Cardinal Bellarmine, did not object to Galileo’s using the hypothesis that the earth goes round the sun as a device for making predictions. His objection was to Galileo’s assertion that heliocentrism is true. As a first approximation, realism maintains that well-confirmed scientific theories should be regarded as true, while empiricism maintains that they should be regarded as empirically adequate – as capturing what is true about observable phenomena. Empiricists deny that it is ever rationally obligatory to believe that theories provide true descriptions of an unobservable reality. It isn’t that empiricists deny that quarks or genes exist; rather, they regard such realist affirmations as going beyond what the evidence demands. Empiricism is to realism as agnosticism is to theism. A third option corresponds to atheism. This is fictionalism, the thesis that scientific theories are always false. A closely related fourth option is instrumentalism, which is often interpreted as claiming that theories do not have truth-values and are merely useful tools for making predictions. In the contest between empiricism and scientific realism, the empiricist’s preoccupation with sense experience takes the form of a thesis about the role of observation in science and the rationalist’s emphasis on reason is transformed into a claim about the indispensable role of the super-empirical virtues (Churchland 1985). For an empiricist, if a theory is logically consistent, observations are the only source of information about whether the theory is empirically adequate. For a realist, the observations
provide information about whether the theory is true, but there are other relevant considerations as well: if one theory is more explanatory, or simpler, or more unified than another, that counts too. Empiricists often dismiss these considerations as merely pragmatic or aesthetic – theories with those virtues are easier to use or more beautiful to behold, and that is all.
