“. . . then our people on that time-line went to work with corrective action. Here.”

He wiped the screen and then began punching combinations. Page after page appeared, bearing accounts of people who had claimed to have seen the mysterious disks, and each report was more fantastic than the last.

“The standard smother-out technique,” Verkan Vall grinned. “I only heard a little talk about the ‘flying saucers,’ and all of that was in joke. In that order of culture, you can always discredit one true story by setting up ten others, palpably false, parallel to it.”

—H. Beam Piper, Police Operation

Piper had a point. Pers’nally, I don’t believe there are any poorly hidden aliens infesting these parts. But my disbelief has nothing to do with the awful embarrassing irrationality of flying saucer cults—at least, I hope not.

You and I believe that flying saucer cults arose in the total absence of any flying saucers. Cults can arise around almost any idea, thanks to human silliness. This silliness operates orthogonally to alien intervention: We would expect to see flying saucer cults whether or not there were flying saucers. Even if there were poorly hidden aliens, it would not be any less likely for flying saucer cults to arise. The conditional probability P(cults|aliens) isn’t less than P(cults|¬aliens), unless you suppose that poorly hidden aliens would deliberately suppress flying saucer cults.¹ By the Bayesian definition of evidence, the observation “flying saucer cults exist” is not evidence against the existence of flying saucers. It’s not much evidence one way or the other.

This is an application of the general principle that, as Robert Pirsig puts it, “The world’s greatest fool may say the Sun is shining, but that doesn’t make it dark out.”²

If you knew someone who was wrong 99.99% of the time on yes-or-no questions, you could obtain 99.99% accuracy just by reversing their answers. They would need to do all the work of obtaining good evidence entangled with reality, and processing that evidence coherently, just to anticorrelate that reliably. They would have to be superintelligent to be that stupid.

A car with a broken engine cannot drive backward at 200 mph, even if the engine is...