Berkeley’s likeness principle is the claim that “an idea can be like nothing but an idea”. The likeness principle is intended to undermine representationalism: the view (that Berkeley attributes to thinkers like Descartes and Locke) that all human knowledge is mediated by ideas in the mind which represent material objects. Yet, Berkeley appears to leave the likeness principle unargued for. This has led to several attempts to explain why Berkeley accepts it. In contrast to ‘metaphysical’ and ‘epistemological’ interpretations available in (...) the literature, in this paper I defend a ‘conceptual’ interpretation. I argue that Berkeley accepts the likeness principle on the basis of (i) his commitment to the transparency of ideas, and (ii) his account of resemblance which he sets out in his works on vision. Thus, I provide an explanation for Berkeley’s reasons for accepting the likeness principle which, appropriately, focuses on his views concerning ideas and likeness. (shrink)