Diamonds are Forever

Abstract

We defend the thesis that every necessarily true proposition is always true. Since not every proposition that is always true is necessarily true, our thesis is at odds with theories of modality and time, such as those of Kit Fine and David Kaplan, which posit a fundamental symmetry between modal and tense operators. According to such theories, just as it is a contingent matter what is true at a given time, it is likewise a temporary matter what is true at a given possible world; so a proposition that is now true at all worlds, and thus necessarily true, may yet at some past or future time be false in the actual world, and thus not always true. We reconstruct and criticize several lines of argument in favor of this picture, and then argue against the picture on the grounds that it is inconsistent with certain sorts of contingency in the structure of time.

The Modal Moving Spotlight Theory

“…However, whereas according to Bacon's view, all of the fundamental facts are permanent, according to the theory defended in this paper, some fundamental facts -in particular, facts about fundamental presentness -are temporary. Given that Bacon also holds that all facts supervene on the fundamental facts and that some (non-fundamental) facts are temporary, it follows that on Bacon's view, there are temporary (metaphysical) necessities (see Bacon 2016, note 27); whereas the theory defended in this paper is consistent with, and in fact implies, the view that necessity implies permanence (see especially Dorr & Goodman 2020).…”

“…andLewis (1973). 11 SeeDorr & Goodman (2020) for some relevant work on the interaction between tense and modality.…”

On the relation between modality and tense

“…In section 4, we at last propose our preferred logic for the interaction of modality and tense and show that it is not beset by the kinds of problems its predecessors face. We conclude our discussion by comparing our view to the one recently advanced by Cian Dorr and Jeremy Goodman (Dorr and Goodman 2019).…”

Is the world a heap of quantum fragments?

“…This is logically equivalent to what Dorr and Goodman call Perpetuity, i.e., If Necessarily /, then Always /-where Sometimes and Always are temporal operators defined in terms of the standard Priorean operators. For a defense of Perpetuity see Dorr et al (2019). 27 At least in the so-called ''Dechoerence Only'' variant-see e.g.…”