Chapter Four begins a transition to themes more typical of the history of science. Kochan starts with a review of Heidegger’s phenomenological history of logic, wherein logic is construed as the science of thinking. In Heidegger’s view, this history is inextricably entwined with the history of the modern subject-object distinction, in particular, and the history of scientific subjectivity, more generally. He reads the history of logic as growing out of early attempts to understand the fundamental relation between thinking and things. This is, above all, an intentional relation, a relation manifest in the subject’s experience of its directedness towards things. Heidegger locates the original impulse of logic in Plato’s claim that ‘the good’ guides thinking in its directedness towards things. Aristotle then formalised this idea by modelling thinking on the proposition, with the good now being denoted by the copula (‘is’), which combines subject and predicate in an intelligible sentence. This move marks the beginning of logic. Heidegger argues that Descartes later shifted the organising principle of intelligibility from the ‘is’ to the subject position of the proposition, in fact, to the first-person singular subject, ‘I.’ Kant then submits the Cartesian ‘I’ to a phenomenological critique, disclosing its content in terms of rules of reason. These rules guide thinking in its directedness towards things, ensuring that the relation is a ‘good’ one, productive of intelligibility. According to Heidegger, this history traces the way in which the informal and implicit rules guiding thinking were first identified, and then formally articulated as a set of rules governing the structure of thought. He calls this process ‘thematisation.’ Heidegger then offers his own contribution to this history, arguing that the rules directing thinking are rooted in a shared tradition, in the subject’s ineliminable ‘being-with-others.’ This move, Kochan argues, allows for a powerful point of contact between Heidegger’s phenomenology of logic and the sociology of logic. Indeed, SSK practitioners also emphasise the rootedness of formal logic in the informal rules of a shared tradition. Moreover, they have developed this insight to a far greater extent than did Heidegger. Here, the combination of SSK with Heidegger allows us to strengthen and expand on Heidegger’s more rudimentary considerations.