For whatever reason, I still remember looking on as a guy challenged an old Dominican who had just said (as a throw-off example) that sickness was the absence of health. “Why not argue that health is the privation of sickness!” The Dominican had no answer, but this is not to say he was unprepared. One can’t be held responsible for preparing responses to crazy questions, and privations are ways of falling short of achieving some goal or fulfillment. If this sounds like a description of health to you, you haven’t been sick much. On the other hand, the objection does point to a problem in the privation account. So long as we just trade in synonyms, like “lack” or “absence”, then there is some sense to speaking of the healthy man lacking sickness. Taken in this way, “privation” and “possession/having” give rise to a homogenous dualism- there is in fact no more reason to call one “the privation” except by fiat. But doesn’t this count as another refutation? It would amount to the claim that there is no difference in things between failure and success.
Still, the dualism of having and privation describes a whole view of the world, though it is not clear how we would characterize it: it amounts to a dualism so far as it sees having as equal to lacking, while at the same time it is a monism so far as it makes the opposition between them not a feature of things but simply a fiat. The things themselves are, apparently, some higher mode of being that divides into having and privation. The very principle of contradiction only expresses relative opposition. “Is” or “is not” are opinion all the way down. The difference between them just depends on what you want to do. But at this point it is not clear how we are saying anything about the world, or how we even could say anything about it.