The notion of ‘Gestalt’ plays a prominent role in Ludwik Fleck’s theory of thought styles. This paper scrutinizes how Fleck adopted the concepts and even methods of Gestalt psychology that he sometimes vaguely refers to. Systematically comparing the argumentation and theoretical outlines of Fleck’s social theory of perception and the principles of some Gestalt theories, this article will show and discuss their similarities and fundamental differences. According to Fleck, both science and individual perception rest on social actions and cultural traditions. (...) In particular, Fleck emphasized the relevance of the common language and collective meanings for the shaping of objects according to the thought style of a scientific collective. In contrast to the principles of Gestalt theories, in Fleck’s view not only the perception, but also the constitution of scientific objects and even the ‘laws’ of perception depend on social and cultural constructions of reality. That leads him to a particular theory of Gestalt perception. (shrink)