Full Idea
Most philosophers are uneasy with understanding the causal aspect of actions in terms of an 'agent' making something happen. They prefer to think of some event in the agent, or state of the agent, making something happen.
Gist of Idea
Most philosophers see causation as by an event or state in the agent, rather than the whole agent
Source
Rowland Stout (Action [2005], 4 'The causal')
Book Reference
Stout,Rowland: 'Action' [Acumen 2005], p.59
A Reaction
There is a bit of a regress if you ask what caused the event or state of affairs. It is tempting to stop the buck at the whole agent, or else carry the reduction on down to neurons, physics and the outside world.