Over time, philosophers and historians of science have introduced different notions of 'ways of thinking'. This book presents, compares, and contrasts these different notions. It focuses primarily on Ian Hacking s idea of 'style of reasoning' in order to assess and develop it into a more systematic theory of scientific thought, arguing that Hacking s theory implies epistemic relativism. Luca Sciortino also discusses the implications of Hacking s ideas for the study of the problem of contingency and inevitability in the development of scientific knowledge