Posted by 838 on March 9, 2006, at 21:05:04
In reply to z... talk to me..., posted by 838 on March 9, 2006, at 20:46:16
that didn't make much sense dammit... shall i have a go with water?
before the scientists discovered the nature of water... it was epistemically up for grabs what water might be. so... for all we knew... it was possible for water to be xyz and it was possible for water to be h20.
so that... is meant to be 'conceivability' or... 'epistemic possibility' (in the sense that given what we know about the world... it surely seems possible a-priori that water could turn out to be XYZ)
then scientists discovered that water = H2O. Then the thought is that... Given that water = H2O in the actual world... Water = H2O in all possible worlds...
So... Lets describe a scenario (twin earth) where things are just the same as the actual world except that the clear watery stuff that fills the lakes and falls from the skies, the drinkable potable stuff is XYZ. Then the thought is that the correct thing to say is that... the stuff on twin earth (in the desctibed scenario) is not water. Are you okay with this? Do your intutions go along with Kripke / Putnam? So... The thought is that given that water = H2O in the actual world... In all possible worlds (in which water exists) water is H2O. So... It is metaphysically impossible that water = XYZ because the reference of 'water' is fixed by the nature of the stuff in the actual world.
And yet... a-priori... we can't tell whether the actual world is twin earth or earth...
epistemically (to the best of our knowledge) it is possibel that water = XYZ
but metaphysically (all along regardless of whether we know it or not) whatever water is (to be determined by science - currently H2O) in the actual world... it is that in all possible worlds. So... there are more epistemic possibilities than metaphysical possibilities i guess...
then there is stuff on centred epistemically possible worlds... theya re meant to be descriptions centred around individuals at a time and place (to build in facts as to where one is and when one is and who one is)... and... a-priori we don't know whether we are describing this world or not...
and then if you can centre an empistemically possible world (or scenario if you prefer) in this way... then... you can talk about relativised metaphysical possibility...
so... lets describe twin earth... that could be this world for all we know a-priori... if we centre ourselves at that world... then twin earth is the actual world (or we can consider twin earth as teh actual world) then... relative to that pov... it would be metaphysically necessary that water = XYZ.
it is cool... describing these possibilities...
and we don't know which 'track' we are on...
apparantly... possible worlds are supposed to be concrete entities that are causally and spatiotemporally isolated from this world...
we don't know which 'track' we are on...
we don't know which world is our world unless there is an observation...
consistent with one interpretation of quantum mechanics...
act of observation throws us into a world
ack.
ack.
time for a smoke :-)
poster:838
thread:618106
URL: http://www.dr-bob.org/babble/write/20060125/msgs/618114.html