Michaelis Michael

Famously, David Lewis argued that we can avoid the apparent paradoxes of time travel by introducing a notion of personal time, which by and large follows the causal flow of the time traveler's life history. This paper argues that a related approach can be adapted for use by three-dimensionalists in response to Ted Sider's claim that three-dimensionalism is inconsistent with time travel. In contrast to Lewis (and others who follow him on this point), however, this paper argues that the order of events captured by so-called "personal time" should be thought of as causal, rather than temporal.

Quine’s general approach is to treat ontology as a matter of what a theory says there is. This turns ontology into a question of which existential statements are consequences of that theory. This approach is contrasted favourably with the view that takes ontological commitment as a relation to things. However within the broadly Quinean approach we can distinguish different accounts, differing as to the nature of the consequence relation best suited for determining those consequences. It is suggested that Quine’s own narrowly formal account fails. Then a consideration of the necessitation approach championed by Jackson and Lewis shows that it does not do justice to the role of acknowledging consequences in determining rationality. I suggest that an approach which puts a priori consequence as the key relation does a better job. The task of spelling out the nature of a priori consequence is sketched, along with reasons to doubt the adequacy of the double indexing approach to analysing the a priori. The sorts of relations we can stand in to theories which allow us to inherit ontological commitments are touched on with a number of important philosophical strategies for introducing belief-like attitudes which nevertheless avoid ontological commitment.