Posted by 838 on March 9, 2006, at 20:46:16
wanna talk to me about 2d semantics???
i am struggling a little...
yup...
but it is important.do you have sympathy for something along the lines of fregean senses?
i do... always have 'cause i'm more into phil of mind than phil of language...
shall i start with some stuff and you can tell me where i go wrong????
problems with direct reference (the notion that a name / expression contributes the referent and nothing else)
frege's puzzles...
hesperous is hesperous is cognitively insignificant (true a-priori) whereas hesperous is phosperous is cognitively significant (cannot be worked out a-priori)
john believes hesperous is hesperous whereas even if john is perfectly / ideally rational he would not be expected to believe (without further info from the world) that hesperous is phosperous.
and there are more... and these are supposed to motivate the thought that expressions don't just contribute the referent... they contribute a 'meaning' or 'sense' or 'mode of presentation' or somesuch as well...
then there are some arguments (kripke's modal argument and epistemological argument and some others) to show that there aren't any such things as fregean senses...
but then how to deal with frege's puzzles without fregean senses...
and then the 2d framework kicks in to try and deal with those cases...
so...
there are two ways in which we can evaluate an expression...
'hesperous is hesperous' is necessarily true (it is true in all possible worlds). this is cognitively insignificant (it is knowable a-priori)... in any world in which hesperous exists... hesperous is hesperous...
'hesperous is phosperous'. kripke... thought that this was necessarily true... in the sense that... in any world in which hesperous exists... hesperous is phosperous. another way of saying that... there is no possible world in which hesperous exists where hesperous is not phosperous. dammit... i need to learn how to do formal modal logic. can you do that?
anyways... the thought is that kripke has shown us that there are expressions that are a-posteriori necessities... a-priori it is possible that hesperous is a different planet from phosporous... but given that hesperous is phosperous in the actual world 'hesperous' designates the object... which is in fact phosperous so the reference is fixed in the actual world and thus in all the possible worlds... hesperous is necessarily hesperous...
so that is metaphysical possibility...
then... there is epistemic possibility...
which tends not to be talked about as possible worlds... tends to be talked about as 'scenarios'. i think they are supposed to be... descriptions rather than worlds (there may or may not be a corresponding world for each epistemically possible description).
so... we can describe a situation (scenario) where things are just like they are now... except... instead of the star that appeared in the morning being the same as the star that appeared in the evening... there were in fact two different stars (or planets or whatever)... hmm.
so... the point is that epistemically... we cannot tell a-priori whether the scenario just described is our world or not... need to do some empirical investigation to figure it out. given the way this world turned out (the subjunctive conditional) it is necessary that hesperous is phosperous.
but if we were located (centred in) the scenario just described (if that world was the actual world) then... it would have been metaphysically necessary that hesperous was not phosperous.
so... there is talk of...
metaphysical possibility (determined by teh way the actual world turns out) need to see what worlds are possible...
epistemic possibility (determined by what is conceivable - though i think that might be problematic...) but i think anything that is not a contradiction can be described as an epistemically possible scenario - which is to say our world could be this way for all we know at present).is this making any sense?
have you read this stuff?
poster:838
thread:618106
URL: http://www.dr-bob.org/babble/write/20060125/msgs/618106.html