Abstract

Abstract The problem of the existence of the objects of knowledge is the main problem in the controversy between realism and anti?realism. This controversy appears on three levels: (i) perceptions, (ii) concepts, (iii) scientific theories. According to perception?realism, things exist objectively; according to subjective idealism, they are only bundles of impressions. According to conceptual realism, genera (classes) exist objectively; according to nominalism, they do not exist (there are only general names). According to scientific realism, the objects of confirmed theories, including unobservable entities, exist objectively; according to phenomenalism, only observable bodies exist. On each level a naive realism and a critical realism is distinguished. On the level of scientific theories direct objects (ideal models) are distinguished from ultimate objects (real entities)