Among objects and events in the world some have been or eventually will be observed. Others never have been and never will be. Current wisdom has it that among these latter are those that are nonetheless observable. Furthermore, the class of observable, not just observed, phenomena determines the empirical import of science. As van Fraassen tells us, a theory is empirically adequate if “what the theory says about what is observable (by us) it true.” (1980, p. 18). If there are quibbles with this picture, they are with the feasibility of a nonarbitrary or a theory-neutral distinction between the observable and the unobservable, but not with the idea that there are observable yet forever unobserved objects and events.

This, however, is precisely my quibble. Concrete items of the world—events and objects—are either observed or unobserved but, I urge, are not in addition observable or unobservable. This is not because I deny that a nonarbitrary or theory-neutral distinction can be drawn.