In this chapter, Mackie presents a defence of Locke against Berkeley's attack on abstraction. It is argued that Locke's theory of ideas primarily concerns our ability to employ words and statements. Locke's theory concerning ideas of numbers is criticized. Three theories of universals are considered: realism, nominalism, and conceptualism; it is concluded, however, that the notion of there being distinct things with which we connect general words with particular things is mistaken. Mackie instead proposes a theory of general words being (...) ‘annexed’ to features of things. (shrink)