 Now, it seems that if presentism is to be motivated by appeal to parsimony, then it must be motivated by appeal to considerations of quantitative parsimony. Presentism and eternalism don’t disagree about the kinds of things that exist. Both presentists and non-presentists tend to agree on the metaphysical kinds (or “ontological categories”) that exist. What they disagree about is the temporal location of the things that exist. Presentism states that everything exists at the present time; eternalism states that there are things that exist at other times. If presentism is to be motivated in this way, then we must justify a preference for quantitative parsimony in this case in the face of the orthodoxy that Lewis expresses. (See Tallant 2013 for an attempt to deliver this sort of argument for presentism. For arguments that justify quantitative parsimony as a theoretical virtue, more generally, see Nolan 1997; Baker 2003; Jansson &amp; Tallant 2017.)