Full Idea
The view that there are two causal relata is widely assumed but seldom defended. But the account based on 'effectual difference' says the form is 'c causes e rather than e*'. One might defend four relata, in 'c rather than c* causes e rather than e*'.
Gist of Idea
One may defend three or four causal relata, as in 'c causes e rather than e*'
Source
Jonathan Schaffer (The Metaphysics of Causation [2007], 1)
Book Reference
'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [plato.stanford.edu], p.3
A Reaction
[compressed] This doesn't sound very plausible to me. How do you decide which is e*? If I lob a brick into the crowd, it hits Jim rather than - who?