Praetorius' book advocates a healthy review and reform of the basic assumptions of much general theorising in psychology. Her central concern is to supply reasons of principle to demarcate the psychological and stave off reductionism. She seeks to derive these results from a handful of principles that she holds must be accepted since they form the very grounds for engaging in any inquiry at all. She employs these to good effect by showing that a number of prominent targets engaged in psychological theorising, including Gibson, Marr, Saussure, Stich and Fodor, are prey to deep-seated confusions about the general relation between language and the world. Similarly, she argues that social constructivists and relativists fall foul of the same oversight. I applaud her arguments against these figures and schools of thought.