Ginger Schultheis (Chicago): Counterfactual Probability
Stalnaker's Thesis about indicative conditionals is, roughly, that the probability one ought to assign to an indicative conditional equals the probability that one ought to assign to its consequent conditional on its antecedent. The thesis seems right. If you draw a card from a standard 52-card deck, how confident are you that the card is a diamond if it's a red card? To answer this, you calculate the proportion of red cards that are diamonds -- that is, you calculate the probability of drawing a diamond conditional on drawing a red card. Skyrms' Thesis about counterfactual conditionals is, roughly, that the probability that one ought to assign to a counterfactual equals one's rational expectation of the chance, at a relevant past time, of its consequent conditional on its antecedent. This thesis also seems right. If you decide not to enter a 100-ticket lottery, how confident are you that you would have won had you bought a ticket? To answer this, you calculate the prior chance--that is, the chance just before your decision not to buy a ticket---of winning conditional on entering the lottery. In this talk, I develop a neo-Stalnakerian, uniform theory of conditionals that allows us to derive a plausible, context-sensitive version of Skyrms' Thesis from a plausible, context-sensitive version of Stalnaker's Thesis, together with David Lewis's Principal Principle.
For the duration of the COVID-19 pandemic, meetings take place on Oxford’s Microsoft Teams during term time on Fridays from 5 pm to 7 pm.
