Okay. So how would you argue that "It's possible for my car to be parked on Main Street" would be a priori? — Terrapin Station
Are you still opposing? — frank
There's no way to know that without knowing something about the city it's parked in, as the city is now, and that can't be known a priori. — Terrapin Station
P is that Superman stopped the train in this manner.
P is true at a physically impossible world.
By virtue of this, we know P is also true at a metaphysically and logically impossible world.
True? — frank
Isn't it logically and metaphysically possible for the laws of physics to be different from what they are? — Echarmion
Concerning modal knowledge, it seems similar to the problem of induction. In order to make alethic modal statements based on a posteriori sources, you need to go from specific examples to general rules. So you are using an inductive process. — Echarmion
By virtue of this, we know P is also true at a metaphysically and logically impossible world. — frank
Isn't it logically and metaphysically possible for the laws of physics to be different from what they are? — Echarmion
I've never really been convinced that the physical/metaphysical/logical distinction with respect to modality makes much sense. — Terrapin Station
Physical possibility is what's possible given the laws of physics. — frank
Yes. P is true at some logically and metaphysically possible worlds. It's also true at some L and M impossible worlds. The point being: we might imagine that possible world semantics is reducing modality to something non-modal, but it isn't. It's an unnecessary distraction. Modal distinctions are just as primitive in distinguishing possible from impossible worlds as they are in sorting out small scale events, so we can dispense with possible world semantics. — frank
Good point. We probably won't be able to claim that knowledge of physical possibility is ever entirely empirical. But the problem of induction doesn't have a rational solution either, so it's a burden to both sides. — frank
Part of my issue with the distinction is due to this. Does the distinction require that we're realists on physical law? I'm not sure. — Terrapin Station
see. But even if we accept that modal statements can be rephrased via possible world semantics to be non-modal, we still need modal knowledge. That is, we need to know what worlds are possible to judge the statement — Echarmion
mind is doing when I go from a non-modal statement to a modal one. "Jack is at his house right now" is clearly a synthetic a posteriori statement. "It's possible that Jack is at his house right now" is also synthetic. What happened to the information in the statement? Part of it was lost, since the modal statement does not include Jacks current whereabouts. But we're still talking about Jack, and we still have some information about him (he's not dead, for example). So the statement must still be a posteriori. Have we just omitted some information? Made the statement more "fuzzy"? — Echarmion
There's an argument that possibility of P is entailed by actuality of P. Would you accept that without the argument? — frank
But is impossibility or necessity included in some non-modal statement? — Echarmion
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