Logic and Language

Alessandra Marra (Tilburg University): Objective Oughts and a Puzzle about Futurity

Speaker: Alessandra Marra (Tilburg University)
Title: Objective Oughts and a Puzzle about Futurity
Time: 16:00 - 17:30
Location: ILLC Seminar Room F1.15

Suppose that, completely unbeknownst to you, a friend of yours broke her leg yesterday. Some moral theorists, linguists and logicians (cf. Gibbard 2005, Silk 2014, Kratzer 1981, Carr 2015) would say that there exists a sense of ought according to which the sentence "You ought to visit your friend at the hospital" is true. That is called objective ought. More generally, an agent ought objectively to do X, if X is the best thing to do in light of all the relevant facts.
I argue that the above definition of objective ought leaves room for a puzzle about futurity: Can objective oughts depend on what will happen in the future? If yes, how to account for those objective oughts that are future-dependent? I investigate two main options: (i) treating the future as a fact and, hence, committing to the inevitability of the future, or (ii) adopting a branching-time account of the future, and weighting future possibilities in terms of their objective probability. I argue that (ii) is more promising. Given an appropriate account of objective probability, option (ii) provides a univocal definition of the meaning of objective oughts without endorsing (i)'s commitment to the inevitability of the future. In the second part of the talk I discuss some implications that such an account has in moral theory and deontic logic. In particular, I show that, if (ii) is adopted, it is possible to construct examples similar to the Miners' Paradox in which reasoning by cases fails for objective oughts.