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In his Enquiry Concerning Human Understanding, David Hume reports a local rumor from a town in Spain conveyed to him, with a healthy amount of skepticism, by a cardinal. The story was about a man who had undergone a rather miraculous recovery from an ailment. As Hume describes it,

“He had been seen, for so long a time, wanting a leg; but recovered that limb by the rubbing of holy oil upon the stump; and the cardinal assures us that he saw him with two legs.”

The townsfolk were all ardent believers in the miracle, and it was accepted by “all the canons of the church.” The story spread and was believed on the basis of testimony, and was able to pass and be sustained as easily as it was, in part, because of a shared trust among members of the community. Nevertheless, the cardinal himself gave no credence to the story. Despite the fact that many people were willing to testify to its truth, a story about such an event is just not the kind of thing that has any meaningful likelihood of being true. The cardinal “therefore concluded, like a just reasoner, that such an evidence carried falsehood upon the very face of it, and that a miracle, supported by any human testimony, was more properly a subject of derision than of argument.”

Hume relates other stories, common at the time he was writing, of people offering and accepting accounts of miracles. He argues that to adjudicate these matters, our evidence consists in our set of past observations. Miracles are violations of the laws of nature. When we consider whether we ought to believe in miracles on the basis of testimony, we must weigh our past observations of the workings of the laws of nature against our observations regarding the veracity of testimony. The former will always win. We will always have more evidence to support the idea that the laws of nature will remain constant than we will to support the belief in eyewitness testimony which reports that those laws have been broken. As Hume himself states, “the knavery and folly of men are such common phenomena, that I should rather believe the most extraordinary events to arise from their concurrence, than admit of so signal a violation of the laws of nature.”

Hume is not just reporting historical fact but is also prescient (though he might object to that characterization) when he says, “men, in all ages, have been so much imposed on by ridiculous stories of that kind.” More than 250 years later, we’re contending with elaborate conspiracies such as shape-shifting reptilian overlords, 5-G towers that transmit coronavirus, vaccines that implant microchips, and wild accusations of widespread voter fraud sufficient to change the outcome of the election. The Q-Anon conspiracy theory even has representation in the House of Representatives. Believers in this conspiracy think that a powerful cabal of pedophilic baby-eating democrats is secretly running the world, and a child-sex ring. A secret whistleblowing governmental agent — Q — is conveying all of this information to true patriots on internet chat rooms. Q-Anon spread in much the same way that the story about holy water being used to grow new limbs spread — through testimony.

Hume points out that the practice of coming to know things on the basis of testimony depends on certain enduring features of human nature.

“Were not the memory tenacious to a certain degree, had not men commonly an inclination to truth and a principle of probity; were they not sensible to shame, when detected in a falsehood: Were not these, I say, discovered by experience to be qualities, inherent in human nature, we should never repose the least confidence in human testimony. A man delirious, or noted for falsehood and villainy, has no manner of authority with us.”

Society couldn’t function if we couldn’t rely on testimonial evidence. The present political climate elicits feelings of impending existential dread — a sense that truth and meaning are bleeding off the page like amateur watercolor, leaving no visible boundaries. The characteristics that Hume describes are being worn down. We’ve been told not to rely on our memories; it is unpatriotic to pay too much attention to the past. There are no behaviors that should make anyone feel shame; to suggest that someone ought to feel ashamed for deceiving and misleading is to “cancel” that person. In an environment immersed in “alternative facts,” there is no inclination toward truth or “principle of probity.” It is little wonder that in this environment people favor the likelihood of the existence of liberal pedophilic cannibals over the likelihood that anthropogenic climate change is occurring.

With the possible exception of the lizard people who can transform into humans, these conspiracy theories aren’t violations of the laws of nature. That said, a similar kind of inductive argument is possible. Most of these conspiracy theories require a level of seamless complicity among many, many people, who then leave behind no compelling evidence. Election fraud conspiracies, for example, require complicity across states, political parties, and branches of government. So, we’re left with two broad options. Either every person played their role in this flawlessly, leaving behind no trace, or the theory is false, and it arose from “the knavery and folly” of human beings as has so often happened throughout human history. There is a much stronger inductive argument for the latter.

All of this has a moral component to it, but it is difficult to know exactly how to identify it. As Hume points out, humans have certain dispositions that incline them toward truth. On the other hand, they also have strong tendencies to believe nonsense, especially if that nonsense is coherent with what they already believed or might otherwise make them feel good. We could say that everyone ought to have higher epistemic standards, but ought implies can — it makes no sense to say that a person ought to use better methods to form their beliefs when their psychologies prevent them from having any control over such things. There may be no ultimate solution, but there might be some chance that things could improve. Making things better might not be a matter of changing individual minds, but, instead, altering the environments in which those minds are formed. Education should be a high priority and well-funded. We must have policies that reward honesty among public officials and there must be serious consequences when our public figures tell lies.