Logic and Language

Julian Schlöder: Fitch-like Paradoxes, the Dynamic Strategy

Speaker: Julian Schlöder
Title: Fitch-like Paradoxes, the Dynamic Strategy
Time: 16:00 - 17:30
Location: Online, via Zoom

This meeting will take place via Zoom. To join the meeting, click https://uva-live.zoom.us/j/82405276346.



*All truths are knowable* appears to entail that *all truths are known*; this is Fitch's paradox. Recent work has generalised the paradox; e.g. *all truths are believable* entails that *all beliefs  are true* and *all knowledge is correctly assertible* entails that *all assertions are correct*. I suggest a general strategy to resolve such paradoxes. The suggestion is that "-able" should be understood dynamically with a backward-looking component. In case of the Fitch paradox, my suggestion is that *p is know-able* means that there is some act that, if executed, imparts the knowledge that *before the act was executed, p*. The modal flavour of such *-able* varies with what the relevant acts are (alethic = possible acts; deontic = permitted acts; etc). In the talk, I lay out the different "Fitch-like" problems, conceptually defend the dynamic/backward strategy (which I trace to the work of Dorothy Edgington on the Fitch paradox) and sketch the general a logical framework to implement this strategy.