It is vital to understand that political correctness is immune to evidence - and I do not mean relatively-immune, such that PC requires an overwhelming weight of evidence to be convinced, but I mean utterly and completely immune to evidence such that unanimity of incontrovertible evidence against PC is still insufficient to induce significant change.
This is important to realize; since it makes clear that time, energy and personal resources expended on trying to convince PC with evidence is that much time energy and down-the-drain and lost - precious resources that could potentially have been expended constructively elsewhere.
The reason that PC is absolutely evidence-proof is that it operates at an abstract level.
But the reason that it superficially appears that PC might potentially be open to evidential refutation is that, although abstract, PC is concerned exclusively with material proxy-measures of its abstractions.
That is the distinctive move which set-apart PC from any preceding ideology.
No amount of evidence could ever convince PC that the United Nations or the European Union are harmful organizations that should be wound-up, nor that race and sex preferences and quotas are a bad thing that should be abolished, nor that African 'aid' causes immeasurably more human misery than it alleviates, nor that governmental control of carbon dioxide production is a ludicrous and deadly policy.
My point is not that these are obviously bad things (although they are) but that they are not open to evidence.
The reason is that the United Nations, EU, affirmative action, African aid and Cap and Trade are the kind of thing which potentially can be adapted into abstract systems for altruistic allocation - whereas the alternatives (involving multitudes of more or less free small scale choices) cannot be so adapted.
Political correctness operates on the assumption that an abstract system of allocation is intrinsically superior to the lack of such a system; and the details can be worked-out in the fullness of time.
That United Nations 'peacekeepers' have been involved - not once but several times - in systematic rape and enslavement is no doubt embarrassing, but is regarded as in no way reflecting upon the validity of the organization - nor of the desirability that ideally the UN should be in charge of the worlds military force.
Because the UN is the kind of thing that could potentially be made into a system of abstract allocation, while having a large number of 'sovereign' nations each with its own military is not susceptible of this kind of systematization.
This is the reason why politically correct people believe in objective moral progress.It is not so much that PC individuals are themselves morally superior to everbody who ever existed in past human generations ('tho there is a bit of that); but that past generations lacked abstract mechanisms for altruistic allocation of goods.
For the sincerely PC, a world containing the UN, EU and AA is intrinsically superior to any and all previous human societies which lacked such things.
My point is not that abstract systematic altruism is a means to some kind of end, but an end in itself.
This is why its effectiveness is of no interest.
African aid might continue to create endemic starvation at a level unknown in previous human history, and societies of such brutality as to beggar belief; but none of this matters, since the system of international aid is precisely the kind of impersonal and systematic resource allocation that PC regards as potentially the highest form of human moral activity.
Political correctness is utterly indifferent to what happens to human beings - and I do not mean relatively insensitive to the consequences of its policies, but utterly indifferent.
This is why evidence has no effect whatsoever.
PC policies are always introduced in the teeth of common sense and without any evidence that they would lead to good outcomes - why then should evidence accumulated after their implementation in any way affect their continuation?
Think of 'hate crime' legislation. The way that this works is revealing of the nature of PC.
Clearly the altruistic goal of hate crime legislation is the allocation of status and power between social groups defined in terms of being either deserving or undeserving.
The way that hate crime legislation is operationalized makes clear that it is utterly abstract and impersonal in its conceptualization.
For there to be a hate crime does not require that anybody is actually motivated by hatred, nor does it require any specific victim of hatred who feels threatened.
Instead the 'crime' is operationally-defined in terms of the use of prohibited 'hate words' or themes or facts.
Hate crime occurs therefore (roughly) when a member of an undeserving group uses prohibited 'hate' language which has defined reference to a deserving group.
There needs to be an individual or an institution guilty of the hate crime, but there does not need to be an actual victim, since the crime is utterly abstract.
This resembles the crime of blasphemy, in some ways; yet the contrast is more striking and significant than the similarity; because the religious obviously believe in the reality of the god who knows-about and has-been-insulted-by the 'hate' language used against him - whereas the politically correct hate crime can occur without the awareness of anyone in the deserving group.
My point is that political correctness has now reached such a level of abstraction that no evidence could ever challenge it. Reform is impossible, on principle.
This means that those who oppose political correctness should not waste time and energy on rational argument with people who are truly PC.
There is no way into the system of sincere PC, no possibility of modifying or moderating it - merely of delaying it.
Of course, political correctness will destroy itself, but in doing so it will inflict damage upon its host societies - the scale of which damage increases with every passing year.
So, if the intention is to minimize damage by destroying PC before it destroys itself; then the implication is that this is a achievable only by (preferably 'velvet') 'revolution' and not by 'reform'; in the sense that the interconnected systems of political correctness with all their PC subverted organizations and institutions must be disbanded, and all the people who sincerely believe in PC must (I hope kindly) be removed from positions of power and influence and replaced with individuals who have not fallen to this virulent form of contagious intellectual insanity.