The book is a systematic study of the issue of self-individuation in the scholastic debate on
principles of individuation (principia individuationis). The point of departure is a general
formulation of the problem of individuation acceptable for all the participants of the
scholastic debate: a principle of individuation of x is what makes x individual (in various
possible senses of 'making something individual'). The book argues against a prima facie
plausible view that everything that is individual is individual by itself and not by anything
distinct from it (Strong Self-Individuation Thesis). The keynote topic of the book is a
detailed analysis of the two competing ways of rejecting the Strong Self-Individuation Thesis:
the Scotistic and the Thomistic one. The book defends the latter one discussing a number of
issues concerning substantial and accidental forms essences properties instantiation the
Thomistic notion of materia signata Frege's Begriff-Gegenstand distinction and Geach's
form-function analogy developed in his writings on Aquinas. In the context of both the
scholastic and contemporary metaphysics the book offers a framework for dealing with issues of
individuality and defends a Thomistic theory of individuation.
