 Adaptation is the one biological concept that is central to most debates over evolutionary psychology. Every theoretical work on evolutionary psychology presents the research tradition as being primarily focused on psychological adaptations and goes on to give an account of what adaptations are (see e.g. Tooby and Cosmides 1992; Buss et al. 1998; Simpson and Campbell 2005; Tooby and Cosmides 2005). Much of the philosophical criticism of evolutionary psychology addresses its approach to adaptation or its form of adaptationism. Let us quickly review the basics from the perspective of philosophy of biology.