Which makes the controversy over unidentified flying objects a lot like everything else these days - and a good candidate to teach us a thing or two about the value of cognitive humility.

Let's start with some data. Pollsters tell us one American in three believes we've had extraterrestrial visitors. And - for once! - there's no partisan divide. According to Gallup, Democrats (32 per cent) and Republicans (30 per cent) are about equally likely to believe that at least some UFOs are alien spacecraft. Belief is somewhat higher among independents, at a robust 38 per cent (and maybe higher still in Roswell, New Mexico).

Somebody's right; somebody's wrong.

Should we decide who by relying on official pronouncements? According to multiple leaks, the congressionally mandated report from the Director of National Intelligence, due any day, will say that the government has no evidence of extraterrestrial visitors. Does it follow that those who believe otherwise are - to take the current argot - living in a realm that's fact-free?

I'll go with no - but it's important to understand why.

For enthusiasts, the toughest challenge has always been Fermi's paradox: If the universe contains other civilizations more advanced than ours, why haven't we found any sign? Our searches have come up nil, even in regions we've swept with care.

Happily, if you're among the believers, you have plenty of ripostes to choose from.

Readers of Liu Cixin's Three-Body Problem trilogy are familiar with the theory that extraterrestrials are quite rationally hiding their locations, to avoid being destroyed by more powerful extraterrestrials. Another idea, proposed by the economist Robin Hanson and his collaborators, is that any "grabby" civilizations out there have expanded so rapidly that we can't detect the signs. Why not? Because their rapid expansions came after the signals we can observe departed their distant galaxies billions of years ago: "If they were where we could see them, they would be here now instead of us." (A thought that for Hanson helps explain why, if more advanced civilizations exist, we shouldn't be trying quite so hard to contact them.) A third possibility is that more advanced aliens exist, and they're neither hiding nor grabby but instead have found a path of technological evolution that doesn't leave the sorts of signals we're capable of searching for.

Fair enough.

On the other hand, the conspiratorially minded might conclude that the US government knows we've had visitors and is hiding the truth (cue Independence Day). For those who take this view, the claims by various government agencies to have no evidence that UFOs are alien spacecraft might serve only to deepen suspicion. After all, if a massive conspiracy has been hiding the truth for decades, the conspirators are hardly going to disclose the details just because Congress says so!

Besides, according to The New York Times, there will be something for everyone in the report. A number of the UFOs spotted by military aircraft over the years remain unidentified (UAPs, the government now calls them, for "unidentified aerial phenomena"). The report is expected to conclude that they aren't part of any known classified program. When Scientific American is forced to admit that "the mind boggles" at the many possibilities, we might reasonably predict that not too many minds will be changed.

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But this should come as no surprise. We turn out not to be good at changing our minds. Our political divisions make this tendency worse. Committed political partisans not only have trouble altering their views on contested political issues; even in everyday life, they seem to suffer from a more general cognitive inflexibility.

That's one of the reasons that what we ought to be cultivating is a general cognitive humility - not just about UFOs, but about much more in the world around us. Like the Handarrata in Ursula LeGuin's The Left Hand of Darkness, we need to gain a keen sense of how little we know.

Cognitive humility involves recognising our biases and shortcomings, in part by cultivating a realistic estimate of our own knowledge and powers of reason. It's a skill that matters. On many contested issues, we tend to make up our minds on which expert to trust only after we know which one takes the same view we do. There's no reason to expect the UFO debate to be any different.

Consider the strangely behaving object currently speeding out of the solar system. Dubbed "Oumuamua", a Hawaiian term for "visitor from afar arriving first", most researchers think it is the remnant of a comet, but Harvard astronomer Avi Loeb argues it has characteristics that suggest a technological origin. One needn't get in the middle of that fight to recognise that a lot of observers have chosen sides according to their priors.

Where does that leave me? In the situation where I think we should most often be. Rather than label the beliefs of UFO enthusiasts false, I prefer to say that, much as I'd like them to be right, I'm not yet persuaded. Perhaps the piece of evidence that will make the difference is right around the corner.

And if extraterrestrial visitors ever do arrive, I suspect they'll have plenty of cognitive humility already (no "Klaatu barada nikto") Otherwise, they'd have far been too busy fighting each other to make their way across the stars.