In Ockham’s Assumption of Mental Speech: Thinking in a World of Particulars, Sonja Schierbaum advances a detailed philosophical reconstruction of William Ockham’s (1287-1349) conception of mental speech. Ockham’s conception provides a rich account of cognition and semantics that binds together various philosophical issues and forms a point of departure for many later and even contemporary debates. The book analyses the role of mental speech for the semantics and the use of linguistic expressions as well as its function within Ockham’s cognitive theory and epistemology. Carefully balancing Ockham’s position against contemporary appropriations in the light of Fodor’s LOTH, it allows us to understand better Ockham’s view on human thought and its relation to language.