“The reasonable man adapts himself to the world: the unreasonable one persists to adapt the world to himself.
Therefore all progress depends on the unreasonable man.” ― George Bernard Shaw, Man and Superman
To some degree it is.
There's nothing wrong with courtesy, politeness, and compassion. However, there are those who take the whole PC thing to a different and ridiculous level, and it could be argued that "PC" is an attempt to limit debate by defining acceptable words and concepts.
Fiddling While Rome Burns
Carthago Delenda Est
"I used to roll the dice; see the fear in my enemies' eyes... listen as the crowd would sing, 'now the old king is dead, Long Live the King.'.."
I'm already gearing up for Finger Vote 2014.
Just for reference, means my post was a giant steaming pile of sarcasm.
Sometimes it's enforced, and no one can deny that that's suppression of free speech.
If you expect people to be rational, you aren't being rational.
I wouldn't say it is "suppressing free speech" because that implies a formal force (the police, the state, etc.) actively punishing people for what they say or do.
I would say that it is "silencing the debate" because it often times is used by those who want to silence any opposition to what they have to say either by shaming them personally, or tainting their image in the eyes of others.