How embarrassing—I forgot who the OP for this argument was. :( Sorry. If you don’t support the claim that I was attacking, then perhaps we don’t even disagree after all.
OK, so you are anti-realist about possibility. Fair enough; so am I. But that doesn’t mean the word “possible” is meaningless in the contexts that I used it in. Here’s an attempt at cashing out one version of “possible” that surely you would agree makes sense:
X is possible iff X is true in some theory in the search space of theories that we ought to use when making predictions.
The claim I was disagreeing with is the claim that determinism does not make sense when combined with FTL interaction. Even if we agree that possibility is just a game we play in our heads, the game still has rules, and the claim I am disagreeing with seemed to be a claim about the implications of those rules—namely, that those rules prohibited the combination of determinism and FTL interaction. But they don’t.
Maybe different people play by different rules. We can have a conversation about what rules we ought to play by. But I’m pretty sure that if we polled people who know about determinism and FTL, most would agree that they are compatible.
As an aside, your analogy with pixies puzzles me. Why did you think I would try to draw a distinction between pixies and FTL travel? Both are computable. Both are possible, by the rules that I and most people I know (and SI) play by.
Well, it seems like the part of this conversation that had to do with the original claim and counterclaim has petered out. Do you agree with this claim:
In a truly deterministic universe, the concept of “faster-than light interaction” is largely nonsensical.
If so, then we can keep going. If not, then we can move on to discuss the nature of possibility and its use against claims like the above. If you are still interested enough in continuing, that is. I won’t detain you against your will.
...
Making testable predictions about empirical reality? That’s a pretty high bar. For example, counterfactuals do not fare well under such rules.
Is it? I’m happy to lower the bar; I didn’t think this definition through very much. But thus far I see no reason to revise it. Why don’t counterfactuals fare well? Are you saying that under my definition of possibility, counterfactuals are impossible? That would mean that we shouldn’t consider theories that involve counterfactuals, which seems to me to be false, though it might depend on what theory of counterfactuals we are using.
I have no strong opinion. I suspect that this claim needs its assumptions fleshed out (e.g. that the speed of light is REALLY the limit of how fast information can propagate).
Why don’t counterfactuals fare well?
Because they are rarely useful for making predictions about reality. Not “never”, of course, just “rarely”.
How embarrassing—I forgot who the OP for this argument was. :( Sorry. If you don’t support the claim that I was attacking, then perhaps we don’t even disagree after all.
OK, so you are anti-realist about possibility. Fair enough; so am I. But that doesn’t mean the word “possible” is meaningless in the contexts that I used it in. Here’s an attempt at cashing out one version of “possible” that surely you would agree makes sense:
X is possible iff X is true in some theory in the search space of theories that we ought to use when making predictions.
The claim I was disagreeing with is the claim that determinism does not make sense when combined with FTL interaction. Even if we agree that possibility is just a game we play in our heads, the game still has rules, and the claim I am disagreeing with seemed to be a claim about the implications of those rules—namely, that those rules prohibited the combination of determinism and FTL interaction. But they don’t.
Maybe different people play by different rules. We can have a conversation about what rules we ought to play by. But I’m pretty sure that if we polled people who know about determinism and FTL, most would agree that they are compatible.
As an aside, your analogy with pixies puzzles me. Why did you think I would try to draw a distinction between pixies and FTL travel? Both are computable. Both are possible, by the rules that I and most people I know (and SI) play by.
Making testable predictions about empirical reality? That’s a pretty high bar. For example, counterfactuals do not fare well under such rules.
I did not know whether you would wish to draw such a distinction or not. Now I do :-)
Well, it seems like the part of this conversation that had to do with the original claim and counterclaim has petered out. Do you agree with this claim:
If so, then we can keep going. If not, then we can move on to discuss the nature of possibility and its use against claims like the above. If you are still interested enough in continuing, that is. I won’t detain you against your will.
...
Is it? I’m happy to lower the bar; I didn’t think this definition through very much. But thus far I see no reason to revise it. Why don’t counterfactuals fare well? Are you saying that under my definition of possibility, counterfactuals are impossible? That would mean that we shouldn’t consider theories that involve counterfactuals, which seems to me to be false, though it might depend on what theory of counterfactuals we are using.
I have no strong opinion. I suspect that this claim needs its assumptions fleshed out (e.g. that the speed of light is REALLY the limit of how fast information can propagate).
Because they are rarely useful for making predictions about reality. Not “never”, of course, just “rarely”.