Abstract

Bas van Fraassen maintains that the actual function of optical instruments is producing images. Still, the output of a telescope is different from that of a microscope, for in the latter case it is not possible to empirically investigate the geometrical relations between the observer, the image and the detected entity, while in the former it is - at least in principle. In this paper I argue that this is a weak argument to support the belief in the existence of exoplanets that, according to van Fraassen, comes with accepting a theory that posits these entities. If a constructive empiricist asserts the empirical adequacy of such a theory, she might be relying on typical realist arguments, instead - of the very same ilk as the ones used to defend the veridicality of microscopic images. Perhaps the time has come for van Fraassen to explain his view on telescopes.