In addition to all the other great points in this thread, most people are appallingly ignorant.
They don't learn much in school (and what they did pick up was tainted by whatever flavor of culturally Marxist propaganda was then in vogue) and derive virtually all their knowledge of the world from the mainstream media, in one form or another, which amounts to more propaganda. If the propaganda is PC, they're going to be PC.
This is coupled with another, deeper cause. In public discourse in the US, it is considered extremely bad form to reference religion or speak of it seriously -especially the Christian religion. (Other religions are ok because they are diverse and cool and seem more exotic.) It is considered a divisive subject, because the US is far from religiously homogenous, and so citing religious obligation or whatever is not likely to convince whoever you are talking to. Reasonable enough. However, the revolutionary separation of Church and State in the Constitution had the effect of enshrining this principle, though it took generations for the principle to be taken to its logical conclusion. If we accept on paper that one religion is as good as another, or none at all, and that it's best to just keep that as a private matter of conscience, then eventually this leads to the conclusion that religion does not matter, that it is a hindrance rather than a help to society, and that all vestiges of it ought to be removed from public society.
This thought process breeds political correctness, for two reasons. First, if God is removed as a source of morals, something else must be substituted -humanity. Since the worship of man is now foremost in the minds of most of the active participants in public discourse, their values reflect that. They celebrate and defer to man's knowledge (science) and variety (diversity.) These become the touchstones of morality for 21st century practical-agnostic society, and with no other objective criteria, all diversity must be treated equally, and all scientific progress praised and applied as quickly to daily life as possible. (Technology almost takes the place of a religious sacrament to elevate mankind.) Secondly, since the new materialistic and man-centered de-facto religion is in the ascent, anything that hearkens back to Christianity or pre-diversity thought (such as making objective value judgments about things) is extremely unfashionable and verboten. Nobody wants to seem like an uneducated, unenlightened, unprogressive, anti-diverse redneck country bumpkin who is out-of-touch with mainstream society (and who is probably racist, anti-semitic, misogynistic, and homophobic, four of the most commonly stigmatized anti-diverse viewpoints.)
Additionally, when people believe in everything, they really believe in nothing, especially not their own cultural heritage. So there's this unfulfilled psychological need for a substitute cultural identity, and that is often fulfilled today by celebrating other, less watered-down cultures, or doing something "proactive" like protesting some perceived injustice with a Facebook picture.
This ties in with philosophy as well. Modern subjectivist philosophy, pioneered by Descartes, concludes that man cannot really be certain of anything. This principle, applied, negates the concepts of reality and absolute truth, because if we cannot know them then, at least practically speaking, it is the same as if they do not exist. Again we have a breakdown into chaos. If God is unknowable, if objective reality is even unknowable, then nothing matters and we're just going to be worm food in some decades anyway, so life is meaningless and we may as well strive to get as much pleasure as possible from it, and the only real moral limitation on that is that, in fairness, we must absolutely not step on or criticize anyone else, because they have their 'right' to happiness just like you do. As people flock to higher education in the hopes that it will help them get ahead in life, they take philosophy classes and imbibe this worldview, since most of them have little knowledge to refute their professors, and even fewer convictions to give them any incentive to do so.
All these factors have been in play and acting in concert for about 50 years now, during which time more and more women have entered public life, and the snowballing political correctness of yesterday is now a stifling, unstoppable juggernaut.
They don't learn much in school (and what they did pick up was tainted by whatever flavor of culturally Marxist propaganda was then in vogue) and derive virtually all their knowledge of the world from the mainstream media, in one form or another, which amounts to more propaganda. If the propaganda is PC, they're going to be PC.
This is coupled with another, deeper cause. In public discourse in the US, it is considered extremely bad form to reference religion or speak of it seriously -especially the Christian religion. (Other religions are ok because they are diverse and cool and seem more exotic.) It is considered a divisive subject, because the US is far from religiously homogenous, and so citing religious obligation or whatever is not likely to convince whoever you are talking to. Reasonable enough. However, the revolutionary separation of Church and State in the Constitution had the effect of enshrining this principle, though it took generations for the principle to be taken to its logical conclusion. If we accept on paper that one religion is as good as another, or none at all, and that it's best to just keep that as a private matter of conscience, then eventually this leads to the conclusion that religion does not matter, that it is a hindrance rather than a help to society, and that all vestiges of it ought to be removed from public society.
This thought process breeds political correctness, for two reasons. First, if God is removed as a source of morals, something else must be substituted -humanity. Since the worship of man is now foremost in the minds of most of the active participants in public discourse, their values reflect that. They celebrate and defer to man's knowledge (science) and variety (diversity.) These become the touchstones of morality for 21st century practical-agnostic society, and with no other objective criteria, all diversity must be treated equally, and all scientific progress praised and applied as quickly to daily life as possible. (Technology almost takes the place of a religious sacrament to elevate mankind.) Secondly, since the new materialistic and man-centered de-facto religion is in the ascent, anything that hearkens back to Christianity or pre-diversity thought (such as making objective value judgments about things) is extremely unfashionable and verboten. Nobody wants to seem like an uneducated, unenlightened, unprogressive, anti-diverse redneck country bumpkin who is out-of-touch with mainstream society (and who is probably racist, anti-semitic, misogynistic, and homophobic, four of the most commonly stigmatized anti-diverse viewpoints.)
Additionally, when people believe in everything, they really believe in nothing, especially not their own cultural heritage. So there's this unfulfilled psychological need for a substitute cultural identity, and that is often fulfilled today by celebrating other, less watered-down cultures, or doing something "proactive" like protesting some perceived injustice with a Facebook picture.
This ties in with philosophy as well. Modern subjectivist philosophy, pioneered by Descartes, concludes that man cannot really be certain of anything. This principle, applied, negates the concepts of reality and absolute truth, because if we cannot know them then, at least practically speaking, it is the same as if they do not exist. Again we have a breakdown into chaos. If God is unknowable, if objective reality is even unknowable, then nothing matters and we're just going to be worm food in some decades anyway, so life is meaningless and we may as well strive to get as much pleasure as possible from it, and the only real moral limitation on that is that, in fairness, we must absolutely not step on or criticize anyone else, because they have their 'right' to happiness just like you do. As people flock to higher education in the hopes that it will help them get ahead in life, they take philosophy classes and imbibe this worldview, since most of them have little knowledge to refute their professors, and even fewer convictions to give them any incentive to do so.
All these factors have been in play and acting in concert for about 50 years now, during which time more and more women have entered public life, and the snowballing political correctness of yesterday is now a stifling, unstoppable juggernaut.