I’m reading a book that I think everyone who is interested in powers ought to read. And would love, if you do. Or at least find very helpful. Regardless of whether or not you agree with the author (Jonathan Beere) on the finer points of Aristotle’s Metaphysics.
I recommended Aryeh Kosman’s new book The Activity of Being a while ago, also for its general relevance to the issue of what a causal power is – Beere & Kosman disagree, and I might be closer to Kosman – but I think that Beere’s study is even better for this purpose.
The book – which, as I say, is by Jonathan Beere – is called Doing and Being: An Interpretation of Aristotle’s Metaphysics Theta. Oxford, 2009. Here a link: http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199206704.001.0001/acprof-9780199206704
Charlotte Witt has also written on this topic. Soon I’ll be able to triangulate!