Abstract

Constructive empiricism is a prominent anti-realist position whose aim is to make sense of science. As is well known, it also crucially depends on the distinction between what is observable and what scientific theories postulate but is unobservable to us. Accordingly, adopting an adequate notion of observability is in order, on pain of failing to achieve the goal of grasping science and its aim. Bas van Fraassen, the originator of constructive empiricism, identifies observation with unaided (at least in principle) human perception. So far, though, he has not put forward any convincing argument to support this (unpopular) stand. He did it on the grounds that it is (allegedly) a matter for empirical investigation and not for philosophical analysis. Nonetheless, he seems to have introduced a criterion for observability that is not the result of any scientific research and is not supported by any scientific theory. Countering his own words, he seems to have instead reflected qua philosopher on how an empiricist should interpret the meaning of the verb ‘to observe’. And then tried to defend his point of view by means of metaphors and analogies. But the very same metaphors and analogies van Fraassen put forward could be used to back up the opposite position. Worse, not only does his criterion counter common sense, it does not work either. Perhaps the time has come for van Fraassen to put forward or endorse alternative criteria of observability.