32Van Inwagen’s Consequence Argument against Compatibilism①

Just the Arguments pp.123-124

P1. If determinism is true, then our acts are consequences of the laws of nature and events in the remote past.
P2. The laws of nature and events in the remote past are not up to us.
P3. If something is not up to us, then its consequences are not up to us.
C1. If the laws of nature and events in the remote past are not up to us, then their consequences are not up to us (substitution, P2, P3).
C2. Consequences of the laws of nature and events in the remote past are not up to us (modus ponens, P2, C1).
C3. If determinism is true, then our acts are not up to us (in our control, within our ability) (substitution, C2, P1).
P4. If our acts are not up to us, then we’re not responsible for them.
C4. If determinism is true, we’re not responsible for any of our acts
(hypothetical syllogism, C3, P4).

論証の流れ自体はわかるが、P4がまさにimcompatibilismであって、それを前提に使ってcompatibilismを攻撃しても、論証の対象が先立ってしまっているのではないか、という点が気になる。例えば、フランクファートの論証はそもそもP4を争っていたはず。とはいえ、これはシンプルなバージョンらしいので、複雑なバージョンではもう少し説得をともなった仕方でP4が提示されるのかもしれない。