 Given the influence of Foucault, we may also locate our discussion of Hacking’s own work on historical ontology here (Hacking 2002). Hacking (1975, 1990, 1995, 2012) has studied in depth the emergence of probability theory and (later) of statistical thinking and the construction of the modern self as key examples of what he terms “historical ontology.” He acknowledges inspiration from both Foucault’s discursive formations and Crombie’s styles of thinking (Crombie 1994), with a dose of Feyerabend thrown into the mix. Like Kuhn (and Friedman), Hacking returns to Kant’s “how possible?” question, the answer to which sets out the necessary conditions for a logical space of reasons in which practitioners can make true or false claims about objects and pose research questions about them. Hacking, too, historicizes the Kantian conception. He likes the term ‘historical a priori’, which Canguilhem once applied to the work of his erstwhile student, Foucault.