Abstract

In this paper I propose a solution to the crucial issue of the number of styles of reasoning. Ever since, in the 1980s, Ian Hacking outlined what he later called the ‘project of styles of scientific reasoning’, for short the ‘styles project’, he has never provided criteria for individuating styles of reasoning. Whether or not certain ways of thinking can be counted as styles of reasoning in the sense of Hacking is a question that has remained unanswered, despite its apparent relevance to various other controversial issues related to the styles project. I shall frame the issue within a view of categorization which begins with the later philosophy of Wittgenstein and culminates with the so-called theory of prototypes in psychological research. My conclusion will be that there is no clear boundary to the category of styles of reasoning and that degrees of category membership for a given way of thinking are determined by its degree of similarity to prototypes such as the statistical style of reasoning.