I've been trying to work out some longstanding concerns I've had with certain types of metaphysics, and counterfactual theories of causation in particular — and the resulting conversation led me to a new worry about counterfactual theories. The worry may be completely off-base, but I'd like to run it by everyone nonetheless, so that at least if I am off I can quickly learn why.
Here's the worry: counterfactual theories of causation aim to understand causation, obviously, in terms of certain counterfactual relationship. The standard semantic Lewis-Stalnaker analysis of counterfactuals, in turn, understands their truth-values in terms of what's true in relevant nearby possible worlds. So, 'if p were the case, q' is true just in case in the closest p-worlds, q is true; and 'if p were not the case, q would not be the case' is true just in case the closest ~p worlds are ~q worlds.
So, in order to analyze causation using counterfactuals, one must be able to account for which worlds are closer than which in "causal" cases. But how is this to be done?
Suppose we adopt a hard-core Humean empiricism and so don't posit any kind of necessitation relation between constantly conjoined events — in other words, we adopt a Humean regularity view of events. In that case, we have the problem of induction. Even if all F's in the past have been followed by G's, the fact that they have all been in the past means that you don't have any empirical evidence that future F's will be followed by Gs. For all your (past) empirical evidence establishes, F's are regularly followed by G's only up until now, and something very different will happen from here on out (e.g. every F will be followed by G's absence). So, for example, even if every time a person has ever dropped a ball in the past, the ball accelerates downward under the force of gravity, on a Humean empiricism one has no evidence that the next time one drops a ball, the ball will go downward; it is just as likely, given your evidence, that the ball will shoot upward, or to the side; etc.
There's another way to put all this: on a Humean view of reality, a world in which a ball accelerates upward is, strictly speaking, no further away (or less like the actual world) than a world in which the ball accelerates downward. All worlds in which a ball does different things must be equally close to the actual world, for there is no necessary connection between events.
But now if that's true, then a counterfactual theory of causation can't get off the ground. One can't analyze Billy's rock-throw breaking a window in terms of anything like the counterfactual, "If Billy hadn't thrown the rock, the window wouldn't have broken" — for again, on a Humean view of reality, if Billy hadn't thrown the rock, worlds in which the window breaks are as close to worlds in which it doesn't.
How, then, can a counterfactual theorist get the relevant counterfactuals to come out right (such that it is in fact true that if Billy hadn't thrown his rock, the window hadn't broken)? Answer: only by assuming some kind of necessary connection between events (such that there are objective grounds for thinking that a world in which Billy doens't throw his rock will be a world in which the window doesn't break). But in that case the counterfactual theory of causation presupposes a Kantian necessitarian metaphysics of causation — in which case the counterfactuals aren't causation itself but rather a reflection of an underlying necessitation of events.
Here, then, is the dilemma:
- Either the counterfactual theorist assumes no necessary connection of events, in which case a counterfactual theory of causation can't get off the ground (for necessary connections are needed to specify closeness of nearby worlds), or else
- The counterfactual theorist assumes necessary connections between events, in which case counterfactuals don't explain causation but are instead explained by primitive causal necessitation.
Is there a way around the dilemma? Can the counterfactual theorist account for closeness of nearby worlds without assuming a necessitarian metaphysics? How?
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