This article seeks to take a step towards recognizing that science can deal with the concrete and individual as well as the universal. I shall concentrate on some of Aristotle’s texts, as there is a long tradition going back to Aristotle, according to which science deals only with the universal, although his work also contains texts of a very different tenor. He tries to improve the process of definition as an attempt to bring science closer to the concrete, but ends (...) up realizing that there are some unreachable limits. There is, however, a second Aristotelian approach to the problem in Metaphysica M 10, a passage which takes scientific rapprochement to the individual further by introducing a distinction between science in potential and science in act. The former is universal, but the latter deals with individual substances and processes. Aristotle himself acknowledges here that in one sense science is universal and in another it is not, a position that raises important ontological and epistemological problems. Some suggestions are also offered concerning the kind of truth applicable to science in act, that is, practical truth.Author Keywords: Author Keywords: Aristotle; Practical truth; Science in act; Science of the individual; Definition. (shrink)