The world is a system and a network: to conceive of men as ‘free’ is to think of them as capable of having, at some past juncture, acted in some fashion other than that in which they did act; it is to think of what consequences would have come of such unfulfilled possibilities, and in what respects the world would have been different, as a result, from the world as it now is.

— Isaiah Berlin, Henry Hardy, and Michael Ignatieff, The Hedgehog and the Fox