- Propositional temporalists hold that some propositions change their truth-value over time. In this paper, I describe a serious problem for temporalists who think such propositions can serve as the contents of beliefs and assertions, and then I evaluate strategies for responding to the problem. In the process, I offer a theory of how we ought to reason and communicate about a changing world.
- The first half of the paper identifies and motivates the problem. First I explain some metaphysics-based motivations for propositional temporalism and contrast it with propositional eternalism. Then in Section 2, I introduce the content problem for temporalism, tracing the origin of the problem to independent arguments given by Gareth Evans and Mark Richard. In Sections 3 and 4, I argue that the content problem runs even deeper than Evans, Richard or their recent supporters suspect. A version of the content problem arises for any temporalist who accepts the popular Stalnakerian model of rational conversations and investigations and three related assumptions about assertoric and doxastic norms. The first norm dictates that speakers and believers aim to contribute truths to the context sets for their conversations and investigations. The second norm dictates that speakers and be- lievers aim at completeness in their contributions to conversations and investigations. And the third norm dictates that speakers and believers aim for their contributions to make a lasting change to the context set. I will show that these three norms are inccompatible if agents believe and assert temporalist contents.
- So can propositional temporalists offer a model for rational conversations and investigations? I think they can. In the second half of the paper, I develop and evaluate three different temporalist strategies for addressing the content problem. The response I favor requires a new understanding of how temporalist propositions interact with context sets. In Section 5, I explain and motivate this theory. A second strategy proposes that we ascribe both temporalist and eternalist contents to agents but only update a context set using the eternalist contents. In Section 6, I develop this “double-content” view and show that there are important cases of cross-time updating which it cannot accommodate. The final kind of response–inspired by John MacFarlane’s work on relativism–insists that temporalists should reject the truth norm for belief and assertion. In Section 7, I outline this response and argue that it requires too radical a departure from the intuitive Stalnakerian framework.
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