Nature again

My colleague Jonathan McIntosh takes issue with my post about nature in Aristotle:

“I like the idea of questioning or challenging Aristotle’s notion of nature, but is it possible that your remarks confuse ‘not being  impeded by an external influence for the fulfillment of one’s nature’ with therefore somehow ‘not  needing any external influences for the fulfillment of one’s nature’? My understanding is that Aristotle is not trying to exclude the role of external influence (indeed, the very idea of nature, or a potency in need of actualization  from the outside ) presupposes it, but is rather talking about those violent, catastrophic external influences (violent or catastrophic, at least, relative to the nature in question) that might knock a thing’s nature ‘off course.’ To use your example, we do gash our knees, but our knees also heal. Why? That’s part of the knee’s  nature, a potency the knee already has that is capable of actualization . Cut the leg off at the knee, however, and it won’t grow back. Why? Because the body’s otherwise natural ability to adapt, respond, heal, etc., has been ‘impeded’ (the capacity for healing has not only been not actualized, but obliterated all together). And as you know, in many areas, especially the ethical and political, Aristotle seems to have a fairly robust account of our need of ‘external influences’ for our potential to be human to be fulfilled. You can’t cultivate the virtue of friendship, for example, unless you have friends to practice, and by whom to be practiced, upon.”