An evolutionary approach provides powerful lenses that correct for instinct blindness. It allows one to recognize what natural competences exist, it indicates that the mind is a heterogeneous collection of these competences and, most importantly, it provides positive theories of their designs. Einstein once commented that "It is the theory which decides what we can observe". An evolutionary focus is valuable for psychologists, who are studying a biological system of fantastic complexity, because it can make the intricate outlines of the mind's design stand out in sharp relief. Theories of adaptive problems can guide the search for the cognitive programs that solve them; knowing what cognitive programs exist can, in turn, guide the search for their neural basis.