Full Idea
Causation by absence should be understood in terms of our explanatory practices rather than as a case of genuine causation. There are indeed no powers at work.
Gist of Idea
Causation by absence is not real causation, but part of our explanatory practices
Source
S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.1)
Book Reference
Anjum,R.J./Mumford,S.: 'Getting Causes from Powers' [OUP 2011], p.131
A Reaction
This seems right, even if from a human point of view some evil person has deliberately desisted from some life-saving action. It is just allowing other causation to happen. A tricky forensic issue, but not an ontological one.