1. HISTORICAL BACKGROUND The purpose of the book is to develop internal realism, the metaphysical-episte- mological doctrine initiated by Hilary Putnam (Reason, Truth and History, "Introduction," Many Faces). In doing so I shall rely - sometimes quite heavily - on the notion of conceptual scheme. I shall use the notion in a somewhat idiosyncratic way, which, however, has some affinities with the ways the notion has been used during its history. So I shall start by sketching the history of the notion. This will provide some background, and it will also give opportunity to raise some of the...