You know, one can be right and rude, or right and polite, or wrong and rude, or wrong and polite.

Whether one is right or wrong, being polite will win you more points than being rude. Indeed, you can be 100% correct, but so rude that you turn people away from your cause -- even people who were already on your side (the famous "Please stop being on my side" phenomenon which we've all experienced!).

And of course at the time you're wrong you don't realize it.

Thus general humility and enlightened self-interest would dictate that being polite is almost always the better option than being rude.

Not advice I always follow, alas, but it's true nevertheless.

Alex