Reductions of all kinds must have something in common: They must “reduce” whatever it is that they aim to reduce. (p.275)

If Xs are reduced, or reducible, to Ys, there are no Xs over and above Ys─to put it another way, there are no Xs in addition to Ys. (pp.275-6)

We can say that phenomena of type A are causally reducible to phenomena of type B, if and only if the behavior of A’s is entirely causally explained by the behavior of B’s, and A’s have no causal powers in addition to the powers of B’s. (p.119)
Phenomena of type A are ontologically reducible to phenomena of type B if and only if A’s are nothing but B’s. (p.119)

(6) Reductionism is true iff for each mental predicate F, there is a physical predicate G such that a sentence of the form ‘ x is F iff x is G’ is analytically true.
(7) Reductionism is true iff for each mental predicate F there is a neurological predicate G such that a sentence of the form ‘x is F iff x is G’ expresses a bridge law.
(8) Reductionism is true iff for each mental predicate F there is non-mental predicate G such that a sentence of the form “if x is F then x is G” is a priori.
「化約」可以有太多意思，想要幾句話囊括各種意思，代價是只能提供較含糊的訊息，就如 Kim 最初的定義一樣。不過，這點其實通常不妨礙討論，因為在較嚴謹的脈絡，當「化約」的意義變得重要，只要稍作釐清就可以避免雞同鴨講。

(8 Nov 2013) ：