Monday, August 5, 2019

Assertion threshold

Some people like me assert things starting with a credence like 0.95. Other people are more restrictive and only assert at a higher credence, say 0.98. Is there a general fact as to what credence one should assert at? I am not sure. It seems to me that this is an area where decent and reasonable people can differ, within some range (no one should assert at 0.55, and no one should refuse to assert at 0.999999999). Maybe what is going on here is that there is an idiolect-like phenomenon at the level of illocutionary force. And somehow we get by with these different idiolects, but with some inductive heuristics like “Alice only speaks when she is quite sure”.


William said...

James T. Kirk: Mr. Spock, have you accounted for the variable mass of whales and water in your time re-entry program?
Spock: Mr. Scott cannot give me exact figures, Admiral, so... I will make a guess.
James T. Kirk: A guess? You, Spock? That's extraordinary.
Spock: [to McCoy] I don't think he understands.
Leonard McCoy: No, Spock. He means that he feels safer about your guesses than most other people's facts.

--Star Trek IV: The Voyage Home

Daniel Vecchio said...

Could the assertion threshold for a proposition vary depending on context? Something like William James's conditions for a genuine option provide a context where one might believe despite insufficient evidence. So perhaps something like this may occur in assertion as well. I would say that one needs the appropriate intellectual virtues to discern the right contexts were assertions are permissible.

Alexander R Pruss said...

Yeah, context variation is surely there. But even in a fixed context I think it varies between persons.