On some level, ALL hypothetical situations are impossible. The universe does not contain that configuration. Some are conceptually further from reality than others, but every single one of them is about a model. Something that’s too far removed from a real model of the universe is probably not interesting to discuss (cf. pinhead angels, unstoppable force vs immovable object, etc).
I’ve gotten into the habit of using the word “counterfactual” rather than “hypothetical”. It makes it slightly more clear that the discussion is not about the universe, but about a model of an alternate universe that may share some (conceptual) features with this one.
It has proven useful in short-cutting unproductive and frustrating discussions to ask the question “what’s the minimal difference between this universe and that one”? In many cases, this question is isomorphic to the question that the thought experiment is intended to illuminate. Good, it’s nice to have multiple frames from which to approach it. In other cases, this question exposes massive flaws in the hypothetical, and saves everybody time.
Hypotheticals are not necessarily untrue, much less impossible.
Nor are all hypotheticals, even the ones that are impossible, counterfactuals—see his brief mention of implication.
I think delving into the difference between untrue and impossible would help here. In a model which contains rules distinct from state, “untrue” means “same rules, different state” (usually a state that’s not obtainable from the current state and rules). “impossible” means “unsustainable under the rules”.
That distinction between rules and state is only in our minds/models, though. In the actual universe, if there is such a distinction to an outside observer, it’s lost to those of us stuck in it, because we can effect neither portion of reality.
note: I’m saying this more confidently than I feel. I would deeply appreciate pointers to any evidence that the universe has rules and state which are somehow alterable separately.
As to “hypothetical” vs “counterfactual”, you’re right that this isn’t a blanket synonym. There are hypotheticals that have unknown truth value rather than being known falsehoods. For purposes of this discussion, and for most interesting thought experiment, the hypothetical situation given is simply false—it does not exist as described in the universe.
That distinction between rules and state is only in our minds/models, though. In the actual universe, if there is such a distinction to an outside observer, it’s lost to those of us stuck in it, because we can effect neither portion of reality.
I don’t know if I agree—it seems to me that our ability to effect changes to one, but not the other, is precisely what defines the difference!
For example, my state is not “standing in the front yard”, though it could be. I could easily make it so. However, there’s a rule against “floating 10 feet up in the front yard without the aid of platforms or balloons, etc”… and I know this is a rule, not a state, precisely because I cannot float!
I think the most interesting hypotheticals are those we do not yet know whether or not they hold.
Untrue means it is not factual, though it could have been in the past or the future or in another location. Impossible means it could not occur in out universe (at least we do not think it could occur given our current understanding of our universe).
On some level, ALL hypothetical situations are impossible. The universe does not contain that configuration. Some are conceptually further from reality than others, but every single one of them is about a model. Something that’s too far removed from a real model of the universe is probably not interesting to discuss (cf. pinhead angels, unstoppable force vs immovable object, etc).
I’ve gotten into the habit of using the word “counterfactual” rather than “hypothetical”. It makes it slightly more clear that the discussion is not about the universe, but about a model of an alternate universe that may share some (conceptual) features with this one.
It has proven useful in short-cutting unproductive and frustrating discussions to ask the question “what’s the minimal difference between this universe and that one”? In many cases, this question is isomorphic to the question that the thought experiment is intended to illuminate. Good, it’s nice to have multiple frames from which to approach it. In other cases, this question exposes massive flaws in the hypothetical, and saves everybody time.
Hypotheticals are not necessarily untrue, much less impossible. Nor are all hypotheticals, even the ones that are impossible, counterfactuals—see his brief mention of implication.
I think delving into the difference between untrue and impossible would help here. In a model which contains rules distinct from state, “untrue” means “same rules, different state” (usually a state that’s not obtainable from the current state and rules). “impossible” means “unsustainable under the rules”.
That distinction between rules and state is only in our minds/models, though. In the actual universe, if there is such a distinction to an outside observer, it’s lost to those of us stuck in it, because we can effect neither portion of reality.
note: I’m saying this more confidently than I feel. I would deeply appreciate pointers to any evidence that the universe has rules and state which are somehow alterable separately.
As to “hypothetical” vs “counterfactual”, you’re right that this isn’t a blanket synonym. There are hypotheticals that have unknown truth value rather than being known falsehoods. For purposes of this discussion, and for most interesting thought experiment, the hypothetical situation given is simply false—it does not exist as described in the universe.
I don’t know if I agree—it seems to me that our ability to effect changes to one, but not the other, is precisely what defines the difference!
For example, my state is not “standing in the front yard”, though it could be. I could easily make it so. However, there’s a rule against “floating 10 feet up in the front yard without the aid of platforms or balloons, etc”… and I know this is a rule, not a state, precisely because I cannot float!
I think the most interesting hypotheticals are those we do not yet know whether or not they hold.
Untrue means it is not factual, though it could have been in the past or the future or in another location. Impossible means it could not occur in out universe (at least we do not think it could occur given our current understanding of our universe).