I am going to use term “real counterfactual” to mean the metaphysical claim that events could have turned out otherwise in reality, and the term “logical counterfactual” to mean the purely hypothetical consideration of something that hasn’t happened.
Decision theory is about choosing possible courses of action according to their utility, which implies choosing them for, among other things, their probability. A future action is an event that has not happened yet. A past counterfactual is an event that didn’t happen. Calculating the probability of either is a similar process. Using counterfactuals in this sense does not imply or require a commitment to their real existence. Counterfactuals are even useful when considering systems known to be deterministic, such as deterministic algorithms. For the determinist, counterfactuals are useful but not true.
An Omega or Laplace’s daemon like agent in a deterministic universe could calculate from exact microstates to exact microstates [*], and so would not need counterfactual macrostates, even of a logical kind. But that does not tell us cognitively limited agents that counterfactuals are not useful to us. We cannot “just” calculate microstates.
And even if the relationship between macrostates and microsates works the way you say, deterministic evolution is a further assumption. Determinism trivially excludes real counterfactuals, whilst having no impact on logical ones (cf compatibilist free will). Determinism is neither a given, nor sufficiently impactive.
[*] although it might hav to exclude itself to avoid Loeian obstacles.
I am going to use term “real counterfactual” to mean the metaphysical claim that events could have turned out otherwise in reality, and the term “logical counterfactual” to mean the purely hypothetical consideration of something that hasn’t happened.
Decision theory is about choosing possible courses of action according to their utility, which implies choosing them for, among other things, their probability. A future action is an event that has not happened yet. A past counterfactual is an event that didn’t happen. Calculating the probability of either is a similar process. Using counterfactuals in this sense does not imply or require a commitment to their real existence. Counterfactuals are even useful when considering systems known to be deterministic, such as deterministic algorithms. For the determinist, counterfactuals are useful but not true.
An Omega or Laplace’s daemon like agent in a deterministic universe could calculate from exact microstates to exact microstates [*], and so would not need counterfactual macrostates, even of a logical kind. But that does not tell us cognitively limited agents that counterfactuals are not useful to us. We cannot “just” calculate microstates.
And even if the relationship between macrostates and microsates works the way you say, deterministic evolution is a further assumption. Determinism trivially excludes real counterfactuals, whilst having no impact on logical ones (cf compatibilist free will). Determinism is neither a given, nor sufficiently impactive.
[*] although it might hav to exclude itself to avoid Loeian obstacles.