Full Idea
A reductionist can hold that the direction of causation is to be defined in terms of the direction of time; but this response is only available if one is prepared to adopt a realist view of the direction of time.
Gist of Idea
We can only reduce the direction of causation to the direction of time if we are realist about the latter
Source
Michael Tooley (Causation and Supervenience [2003], 4.2.1.2)
Book Reference
'The Oxford Handbook of Metaphysics', ed/tr. Loux,M /Zimmerman,D [OUP 2005], p.400
A Reaction
A nice illustration of the problems that arise if we try to be reductionist about everything. Personally I prefer my realism to be about time rather than about causation. Time, I would say, makes causation possible, not the other way around.