Techniques of constructive criticism aim to improve the behavior or the behavioral results of a person, while consciously avoiding personal attacks and blaming. This kind of criticism is carefully framed in language acceptable to the target person, often acknowledging that the critics themselves could be wrong. Insulting language and hostile language are avoided, and phrases are used like "I feel..." and "It's my understanding that..." and so on. Constructive critics try to stand in the shoes of the person criticized, and consider what things would look like from their perspective. 
Which brings us to another thing that comes with dogma: heresy. Heresy means those beliefs that undermine the orthodox consensus, so it must be eradicated: by education, by reeducation—if necessary, by censorship. It makes a perfect, dreary sense that there are speech codes, or the desire for speech codes, at selective private colleges. The irony is that conservatives don’t actually care if progressives disapprove of them, with the result that political correctness generally amounts to internecine warfare on the left: radical feminists excoriating other radical feminists for saying “vagina” instead of “front hole,” students denouncing the director of Boys Don’t Cry as a transphobic “cis white bitch” (as recently happened at Reed College), and so forth.