Rules, rationality, and imagination: The role of the primitive and natural in Wittgenstein's later philosophy

Many commentators of Ludwig Wittgenstein believe him to have made certain claims about human nature in his later writings. Wittgenstein is supposed to have attributed to all humans---or at least those of the same "form of life"---behavioral dispositions that are natural, unlearned, and antecedent to our participation in any intelligent activity. These commentators believe that Wittgenstein used these predispositions to account for at least one of the following: how we acquire natural language; its origins; and how it is that we succeed in being competent members of rule-governed practices, especially given the ambiguity of rule-interpretation. However, in this dissertation I offer an alternative interpretation of the remarks which have inspired this interpretation, those in which Wittgenstein makes references to things like "primitive reactions" and human "natural history." I show how the claims about human nature that Wittgenstein seems to be making are only possibilities that he asks us to imagine in order to highlight important grammatical features of our rule-governed practices. In particular, the feature of these practices that Wittgenstein is most concerned to highlight is the confidence its participants must exhibit in their performance of the ordinary moves of the practice. Given this feature, we are compelled by a certain tendency of thought to imagine for our practices---if asked to do so---a particular genealogy and explanation for the ease with which we acquire them and continue to perform them, i.e., that these practices develop from natural predispositions and our competent performance in them is an expression of our human nature. But whether these things are true has no bearing on the accuracy of Wittgenstein's grammatical observations. In the final part of the dissertation, I derive from these observations a new model of rationality that is superior to the traditional model, which has been represented by radical scepticism. This new model shows that being rational does not consist in being able to rehearse completely the justifications for one's beliefs and actions (and thus satisfy the radical sceptic). Rather, it consists in being in a certain kind of conformity with the other participants of a rule-governed practice.