I've met people who get huffy about the suggestion that they preface their opinions with "in my opinion" or "I think that." For a long time I had trouble explaining what good came of doing so; the best I've got so far is "it distinguishes you from the people who think their opinions are facts." Does this make sense? Any suggestions for making it clearer?

Edit: I just found a couple more ways to explain this in my notes file. One is that "x is bad" invites the conversation "no it's not!" "yes it is!" (because it's a disagreement of fact) whereas "I think x is bad" invites the conversation "why do you think that?" (because it's a disagreement of opinion). The second argument is more interesting. Another is that when you say "x is bad" as an absolute, you're implying that anyone who likes it is wrong; you're insulting their taste. When you say "I don't like x" you're merely disagreeing with their taste.

I haven't yet figured out to do with people who actually do believe that their opinions or experiences represent objective truths.