...and of how it differs from most other people's ideas, is that I see PC as underpinned by psychology: specifically by hereditary psychology, specifically by the abstracting ability and tendency to abstract.
In other words, I regard purely cultural theories of PC (i.e. everyone else's ideas of PC!) as fundamentally deficient since they neglect that most people in the history of the world have been biologically incapable of political correctness.
In yet other words, I see PC as a by-product of high general intelligence (roughly, high IQ).
It is high IQ which sustains the thought processes which characterize political correctness and its related forms of nihilism (such as Liberalism, scientism, vitalism, socialism and communism, anarchism and so on).
These types of thought are not possible to the majority of people in the world due to relatively low IQ - or at least they are so alien and unspontaneous as to be merely temporary or a pretence.
Almost anyone will go-along with PC when it is expedient; but PC could not be established and dominant in a society unless
1. there were a lot of people of high IQ/ abstracting tendency and
2. the ruling class is (more or less) composed of such people.
This required, in the first place, societies in which IQ was selectively advantaged across an evolutionary timescale. Then the evolution of these societies such that the most intelligent, by and large, became the rulers of society.
So, PC has become dominant as the ruling classes became more-and-more IQ meritocracies (instead of military meritocracies, or religious meritocracies).
And this domination happened as a by-product of modernity (increasing productivity per capita, due to the technological breakthroughs mostly created by the high IQ elite; continual increase in functional specialization etc.).
Therefore (like Greg Clark in Farewell to Alms, or Cochran and Harpending in the 10000 year revolution) I see the rise of modernity as depending on the prior rise in intelligence (and the taming of personality) resulting from certain types of selection pressure in extreme latitude and then agricultural societies where spontaneous violence is suppressed for many generations.
And I see this same increased intelligence and tamed-personality as being the underlying (permissive) cause of political correctness.
High (abstracting) IQ and a tamed personality have set in process a series of evolutionary societal changes which first led to modernity, but are now leading to the destruction of modernity.
At first this process was constrained by religion - specifically by Christianity in the context of a divinely ordained monarchy. Under such a system intelligence is constrained by religion, held in check, must work within that context.
But the abstracting tendency of the high IQ elite has progressively dismantled these constraints (in order to 'liberate' the intellect - a process first unambiguously seen in the prideful genius of Peter Abelard - 1079-1142).
The autonomy of abstracting intelligence is not, in principle, irreversible - since there is always a possibility of repentance and restoration of divinely-ordained monarchy. But, in the West, the process has not in fact been reversed - except locally or temporarily, once the process had begun.
The evolution of intellectuals, then Western domination by intellectuals; and the pride of intellectuals (their assertion of freedom from the constraints of religion, their resulting sense of their own omniscience and omnipotence) was therefore the root of the rise of modernity; and it is now the root of its rapidly accelerating destruction by political correctness (among other related factors).