In the Meno, Phaedo, and Phaedrus, Plato outlines the controversial thesis of a priori knowledge that all learning is a form of recollection-anamnesis. He uses this as an argument for the immortality of the soul via reincarnation. Because of this latter claim, the thesis is widely mocked by contemporary evolutionarily-informed materialists. But we can safely reject the metaphysical claim without abandoning the insight of the epistemological one. And indeed, modern evolutionary theory can explain how learning-at least of the sort that depends on certain a priori concepts-can be a kind of recollection. Through this metaphor, natural selection is a process by which information about the world is transmitted across time. When we learn by reasoning about a priori knowledge, then, we in an important sense rely on information in our genomes-if not our souls-information acquired by the process of natural selection-if not conscious acquisition. Thinking of a priori knowledge with the metaphor of anamnesis elucidates two essential features of the relationship between epistemology and ontology. First, it emphasizes that there is necessarily a time-delay between our a priori knowledge and the universe to which it bears a relationship, if any. Second, it clarifies that a priori knowledge is knowledge that enhances reproductive fitness-which could well be because it reflects ontology faithfully, but could as easily be a kind of innate nominalism.
