The subject of inquiry is Galen’s logical heritage where some aspects are distinguished which are closely connected with his medical practice. In this respect most interesting proved to be his views on hypothetical logics, especially from the point of view of his slogan ‘Pay attention to things not words’. Galen thinks that there are three ways in which a pair of states of affairs might be related: they might be in conflict, in consequence, or in neither relation. This Galen’s classification of relations between states of affairs might be represented in form of a specific ontological square