This paper presents a version of analytical Thomism that brings the principles of Aquinas into systematic and sustained contact with the sciences as opposed to contemporary philosophy. The leading idea of this version of analytical Thomism is to test the viability of scholastic principles by seeing if they provide the resources to cope with problems emerging from the natural and social sciences. If they do, then Thomism vindicates itself in the marketplace of ideas. If not, then the analytical Thomist knows (...) where the perennial philosophy needs further development and perhaps revision. The first part of the paper sets out the rationale for this project. The remainder of the paper illustrates this approach by examining a problem emerging from evolutionary biology, namely, the provision of a theory of individuation for living entities. (shrink)