What is political correctness?
Too often people, including writers here, have caricatured people who hate political correctness as those wanting to belittle minorities and women. Political correctness indeed, in the question details' words, mean different things to different people. In this content, I will attempt to dissect the concept.
Political correctness applies to two areas: viewpoints and expressions.
Moral high ground. Consider the pro-life argument, which claims the moral high ground:
The unborn baby is a human being, and has its own rights. His/her rights to survive precede the rights of the choice of the mother. We have a responsibility as human beings to protect the weakest members of society, the most defenseless. Today that is the infant in the womb.
If you do not subscribe to pro-life views, be prepared to be labelled as a murderer who dehumanizes the unwanted in conservative circles.
Neither conservatives would like it if you propose the reason why would gays would want to marry is the same as those of heterosexuals, and people who do not agree with it is homophobic.
When you are not on the moral high ground, appealing to goodness and emotion no longer work, and you are forced to make a convoluted argument. You need to be compromise certain aspects of morality, and it is difficult to feel still awesome for that. Some things are not correct just because that they are at the moral high ground and hence the expression ‘politically correct doesn't mean that you are correct'.
Socially acceptable. The other side of the abortion debate is also politically correct, but in a different aspect.
Consider this Quora thread on abortion. While I understand this question is a product of a messy question merging, the question is flooded with pro-choice views. The first pro-life argument is buried deep within and had to be saved from collapse by downvotes. On Quora, it is socially unacceptable to be pro-life, and politically correct to be pro-choice.
Put yourself in the shoes of a religious conservative who considers that the society is mistreating the unborn. You will be frustrated at how liberals are censoring people who propose that the fetus is a human being. When you post a pro-life view, do be expected to be flooded with retaliatory comments. They are doing the same to those who are not pro-immigration, pro-Islam, pro-feminism ... and pretty much everything liberals are defending. In other circles, there may be a different set of socially acceptable viewpoints.
This is perhaps what someone means when he says political correctness stifles debate. But we need to consider that every community formed will soon converge to a consensus and gather like-minded people. However, it is a problem if opposing viewpoints are suppressed and ostracized, resulting in an echo chamber.
Delusion and accuracy. Some expressions sugarcoat the situation and denies the real problem at hand.
We have never been a nation of haves and haves-not, we are a nation of haves, and soon-to-haves, of people who have made it, and people who will make it.
This politically correct expression is so potent to it can make people believe that anybody can succeed, and it is solely one's fault if he didn't. People who had been disillusioned with the equality of opportunity will call this statement bullshit that has deceived people who have not experienced poverty.
Some euphemisms are used to sanitize all the negative connotations associated with the original word. Here is an example:
Both of them were uncooperative at first ... the application of enhanced interrogation techniques specifically waterboarding especially in the case of Khalid Sheikh Mohammed and it's what really persuaded him he needed to cooperate.
However, politicians and government officials may refuse to admit that their great nation carries out torture because of all its negative connotations. They choose the euphemism instead, in an attempt to conceal the hideous acts. Political correctness in the form of delusion is thus commonly hated.
However, another word that some people think is deluding as well is ‘pro-choice'. Many pro-life activists refuse to acknowledge the terminology because it is deluding as it is simply ‘pro-abortion'. However, you should be expected to respect and recognize the existence of your opponent, and call them what they label themselves as (‘pro-life' sounds good too).
It is also very important to be politically correct in international politics. If you do not use the two names for the Senkaku/Diaoyu islands, your argument will not be taken seriously. Countries also need to recognize the one-China policy before beginning diplomatic relations with the PRC. The fuss over political correctness may seem to be excessive and sometimes amusing, but the legitimacy of certain parties is at stake here.
The euphemism treadmill. The intention using of politically correct terminology - to be inclusive and neutral - is indeed noble.
deaf - hearing impaired
blind - partially sighted / visually impaired
stupid / retarded - learning disorder / minimally exceptional
We should always avoid using terms that are used to insult people, and maybe that includes deaf, blind, stupid or retarded. It is, however, counterproductive to substitute it with ambiguous terms, like "minimally exceptional". "Learning disorder" or the exact description of the disability serves is far more precise than "stupid" or "retarded".
But then, some people, including George Carlin, was still frustrated that the politically correct term requires far too many more syllables. They prefer simple honest direct language and insist that there is no shame in words like ‘cripple'.
Even worse, the trend of people avoiding that word may be actually why there is a shame associated with the word.
Moreover, as there will always be assholes who want to hurt others, they will move on to the usage of other terms in their insults, for example, "autistic". Does this mean we need to move away from that word? New words replace hurtful language, but individuals remain stuck on the euphemism treadmill.
The extreme standards. On the other hand, some modern feminists are pushing the limits of inclusiveness and the eradication of all gender stereotypes. They take offense with language youth typically use: