Full Idea
Jessica Wilson (1999) says what makes physicalist accounts different from emergentism etc. is that each individual causal power associated with a supervenient property is numerically identical with a causal power associated with its base property.
Gist of Idea
The hallmark of physicalism is that each causal power has a base causal power under it
Source
Lynch,MP/Glasgow,JM (The Impossibility of Superdupervenience [2003], n 11)
Book Reference
-: 'Philosophical Studies' [-], p.218
A Reaction
Hence the key thought in so-called (serious, rather than self-evident) 'emergentism' is so-called 'downward causation', which I take to be an idle daydream.