In learning negation I asked whether we learn the principle of contradiction, and the concept of negation, by observation and experience, or whether it is somehow 'hard wired' into our consciousness. I didn't spell it out, but I was implicitly making two claims. One, that negation is 'hard wired'. Two, that the principle of contradiction follows directly from our concept of negation, i.e. anyone who insists on the possibility that "Socrates is white and Socrates is not white" simply cannot have understood the meaning of 'not'.
Taking the first. It is absurd that the concept of negation is anything we could learn. How, e.g. could you see that something is not white without understanding what negation was, even if you hadn't learned the word 'not' which corresponds to it. Understanding that something is not the case is no less fundamental than understanding that it is the case (presumably those who believe we learn the concept of negation would not defend the learning of affirmation – how would we learn the idea of being the case?). Ergo, the concept of negation is hard-wired.
The second point is harder to prove. I would like to argue that it is a consequence of the position which I have frequently defended here, namely that to assert that p is true is simply to assert p, and that to say that p is false is simply to deny that p. I.e. truth and falsity reduce to affirmation and denial. Does the principle of contradiction follow from this?