I have a long-running argument with friends that the word "opinion" has more to do with how something is expressed, not whether it is true or not. That is, "I think it is raining outside" sounds like an opinion, but is actually fact, because I do in fact think it. And "The Beatles are my favorite band" is a fact. Further, if someone sprays water in front of my window right before I look out, and I claim "It is raining outside," then that is still a statement of fact. It happens to not be true.
And finally, claiming "The Beatles are the best band in the world" is a statement of fact. Most people automatically assume you are quietly adding "I believe that..." in front of that statement, so they assume that you are stating an opinion. I would argue that it is an incorrect fact, as opposed to being an opinion.
Am I simply misunderstanding the generally accepted meaning of those words? Is this just a semantic issue? Does being a "fact" require validity? If so, then when new evidence comes to light, like it does in science all the time, do facts change, do they simply lose their correctness, do they cease being facts? Other than time-related statements, like "my cat is alive", I have a hard time accepting that facts change this way.
The problem I have with my own argument is that it does away with the existence of opinions. Since I really do think anything I claim I think, then everything I preface with "I think that" is by definition a fact. But that just feels dumb and pointless. Am I just behaving like a 5 year old philosopher?