Suppose Alice believes p. Does it follow that Alice disbelieves not-p? Or would she have to believe not-not-p to disbelieve not-p? (Granted, in both classical and intuitionistic logic, not-not-p follows from p.)
Maybe this is a merely verbal question about “disbelieves”.
Or could it be that disbelief is a primitive mental state on par with belief?
2 comments:
Why would that follow? Couldn’t Alice believe P and not-P? Don’t people sometimes believe contradictory things without realizing it? In which case, she would believe not-P and disbelieve not-P, which sounds odd to me.
It doesn't seem odd to me to say that someone who contradicts themselves might believe and disbelieve the same thing. But perhaps we do need to complicate the account of disbelief, and say that to disbelieve p you need to believe either the negation or the negand of p AND not believe p. (The term "negand" isn't much used. It's one of my favorite words.)
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