Everyone has, at some point, encountered the notion that opinions can be neither true nor false. Which is true to some extent, in my opinion.

An opinion is a statement of belief. The only truth that can be drawn fron an opinion is that the person stating it holds the belief. You can't infer from the opinion that there is any fact behind it. Thus, you can honestly hold the opinion that "X is true", even when X is, in fact, false.

The problem is, though, that having half-heard and not understood this concept, people get it into their heads that because an opinion can neither be true nor false, this means they're allowed to hold any opinion unchallenged. "It's just my opinion", they say. "Opinions can't be false, they just are!"

"Don't hassle me with your... facts!"

While an opinion may not be false, it can be irrational.

Opinions generally represent some objective truth that can be true or false. That objective truth can be argued. And if you are left with an opinion that you have no justification for holding, then while you can continue to hold that opinion as long as you want, you are no longer rationally holding that opinion.

I last ran into this arguing over a beer with a couple of strangers about the Apollo moon landing. Now on one side of this argument, we have a bunch of plausible-sounding objections, none of which bear up to close scrutiny, and all of which have been thoroughly countered. On the other side of the conspiracy theory, you have to hold the belief that of the hundreds of people who would have had to be involved in the hoax, most of whom were committed scientists rather than the usual gang of black-clad government agents, and who are now getting to the "setting the record straight" kind of age, none have actually come forward and admitted they made it up.

So after going through the usual gang of of objections—the stars and shadows, and so on—and extracting grudging admissions that the chance of a conspiracy that big and with that many people involved staying secret so long is incredibly low, we ended up back at the same old place. "It's just my opinion that it never happened. Opinions can't be false, right?"

People believe they have some right, some moral imperative to hold any stupid opinion they want. I'm sure in the USA, it's even Constitutionally protected. You have the God-given right to hold any damn opinion you want, even if it runs counter to every single fact you've encountered.

Where's my God-given right not to be subjected to stupidity?