 McTaggart by and large proceeds deductively by appealing to propositions he holds to be synthetic a priori and then deriving further claims from them. McTaggart does allow that experience has a role to play in metaphysical inquiry, albeit a limited one. McTaggart’s The Nature of Existence explicitly appeals to two empirical claims, first that something exists and second that what exists is differentiated, i.e., has proper parts. McTaggart holds that only the former claim is knowable only by experience; the latter claim is derivable, he claims, from the synthetic a priori position that everything has proper parts. This latter claim will be further discussed in sections 6 and 8 of this article.