Regularity theories of causation

A causes B if and only if A-type events are always followed by B-type events (Hume₁)

• If Hume is right, then there cannot be one-time causal pairings.
• Also, if we think about the first time that an A is followed by B, then whether A causes B depends on the future.

“A causes B” is defined in terms of A entering into a law-based explanation of B.  Laws are defined in terms of regularity: the laws are that description of reality that achieves the optimal balance between expressive power and brevity (Lewis).

Counterfactual theories of causation

• Were p to hold, q would hold (pÿ®q) is true provided that either:
• p holds at no world, or
• there is a world w where both p and q hold (“the witness to the conditional pÿ®q”) which is closer to the actual world than any world w* where both p and ~q hold. (Lewis)
• Simpler version (Stalnaker): pÿ®q is true provided at the closest world (to ours) at which p holds, q also holds.
• An actual event F causally depends on an actual event E provided that E and F happen, but were E not to have happened, F wouldn’t have happened. (Lewis, Hume₂)
• E causes F if and only if there is a sequence of events, starting with E and ending with F, where each item in the sequence, other than E itself, causally depends on the previous.
• Problems:
• Correlated epiphenomena
• Asymmetric overdetermination