In one of his most (in)famous contributions to the history of philosophy, David Hume argued in his An Enquiry into Human Understanding (1748) that one never has good reason to believe in the occurrence of miracles. In a nutshell, his case is as follows. If we define a miracle as a violation of the laws of nature, then if somebody tells you that they witnessed a miracle, in order to justifiably believe that what they saw really was a violation of a law of nature, then you would need to believe the following: That it is more likely that a violation of the law of nature occurred than it didn’t, which means treating the testimony of your interlocutor as more weighty than the sum total of all accumulated human experience, which tells us that violations of the laws of nature do not, in fact, ever occur. The crux of Hume’s challenge, however, is that we are never in a position to treat somebody’s testimony in favour of witnessing a miracle as more weighty than the sum total of human experience telling us the opposite. (Or for that matter, to believe ourselves if we think we might have witnessed a miracle first hand – chances are, some other, altogether more mundane explanation, fully in line with the laws of nature proceeding as normal, is available.) Conclusion: we should never believe in miracles.
Hume’s argument continues to beguile and provoke philosophers and theologians to this day. Some herald it as a knock-down argument against revealed religion; others hold it to be an incoherent philosophical failure. Yet whatever the case may be regarding Hume’s showpiece argument as a whole, what has tended to go unnoticed is something else that he points out: the bizarre propensity human beings have to believe in the supernatural precisely because claims of the supernatural are inherently ridiculous and improbable.
In the course of ordinary affairs, Hume notes, we “commonly conduct ourselves in our reasonings” by the “maxim” that “objects, of which we have no experience, resemble those, of which we have; that what we have found to be most usual is always most probable; and that where there is an opposition of arguments, we ought to give the preference to such as are founded on the greatest number of past observations”. In other words, we standardly fit our strength of belief to the available evidence. The more probable something seems based on what we know as a whole, the more we tend towards believing it; the less probable, the less we tend to believe it.
But not, it seems, when it comes to things affirmed which are “utterly absurd and miraculous”. In these cases, there seems to be a sort of bug in our mental code. Hearing improbable stories of miracles – stories which go against everything we know about the uniformity of the laws of nature – instead of entirely discounting belief in such vastly improbable occurrences, Hume claims, flips something in our mental processing. We have a tendency to believe in these improbable occurrences because they are so improbable. The mind “more readily admits of such a fact, upon account of that very circumstance, which ought to destroy all its authority”.
An example here is helpful, updated to a more modern context. Imagine I showed you black and white photos of men in military uniforms in a desert holding bits of silver wreckage. Given everything we know about the universe, the chances are that this wreckage is something like a weather balloon, or remnants of a downed aircraft. But what if I told you that the metal debris is in fact part of a crashed spaceship that landed near Roswell in 1947, an incident which was then deliberately covered up by the US government to hide its contact with extra-terrestrials? Most people would roll their eyes at this. But lots of people do the opposite: they instinctively believe this latter, utterly improbable account (aliens), at the wholesale expense of more probable explanations (weather balloon; crashed fighter jet). Crucially, Hume’s point here is not just that the people who believe they are seeing evidence of little green men believe this in spite of the abundant evidence against such a theory being true (think about it: literally everything else we know about reality tells against this being the best explanation for what’s in the photo). It’s weirder than that. They are drawn to believe the improbable explanation (spaceship) precisely because it’s so improbable. The mental processing has, so to speak, gone haywire, issuing in beliefs inversely proportional to the reasons we have for believing in them.
Hume names this disposition “the propensity of mankind towards the marvellous”, and notes that it is especially powerful when it comes into contact with religion: “if the spirit of religion join itself to the love of wonder, there is an end of common sense”. After all, the claim that some bloke two thousand years ago walked on water, fed 5000 people with a loaf of bread and a couple of fish, and then later rose from the dead, is on the face of it patently ridiculous. But add into the mix the desire to believe in an omnipotent all-loving deity who has a plan for you (so don’t worry, death is not the end), plus also the effects of charismatic preachers, and you’ve got a sure-fire recipe for humans sincerely believing in all kinds of nonsense.
Yet crucially for Hume, this tendency to believe in nonsense goes deep. That bug in our mental code whereby when it comes to the “utterly absurd and miraculous” we tend to increase our belief in strange things because they are so inherently improbable (when it should be the reverse) means we are all at risk of lapsing into superstition: of believing in the inherently absurd, against all available evidence. This is an important reason, he thinks, why belief in the occurrence of miracles is so persistently hard to dislodge.
Assuming Hume is right about this bug, it raises some perplexing questions. For a start, why are we like this? The importance of testimony is here likely to play a role. On the one hand, it’s pretty clear that human beings have gained massive historical, and probably evolutionary, advantages from being able to pass on testimony to each other. There were clearly great gains to be had not only from being able to tell each other “there’s a tiger over there”, but in standardly believing other people when they tell you there’s a tiger over there. Of course, sometimes there might be a “boy who cried tiger” – but believing him is not costly in the way that, say, insisting every time on going to check for yourself is going to prove. Better to play it safe, take their word for it, and try not to be the slowest runner.
In general the vast majority of what we know, we know because other people have told it to us. Take the paradigm logical deduction “All men are mortal, Socrates is a man, therefore Socrates is mortal”. All good, so long as you buy that first premise: that all men are mortal. Most of us, I assume, do believe this. But why? In my experience, most people I know are still alive, and only a tiny handful of people I have ever known have died. Why not conclude that the rest are immortal? Well, because the overwhelming testimony of the species is that all humans die – and I go with the testimony, and make it a bedrock belief.
This all makes sense, and is plainly very useful. What makes less sense is why something like Hume’s “propensity of mankind towards the marvellous” should have arisen. Perhaps at some point in our history there was an advantage to this bug in our mental code; maybe our tendency to do what shamans and witchdoctors told us based on improbable supernatural claims helped consolidate group hierarchies, bonding, cooperation, or some such. Or perhaps it is what evolutionary biologists call a “spandrel” – an accidental offshoot of some other beneficial adaptation which itself serves no advantageous purpose (such as the human earlobe, or on some accounts, our enjoyment of and capacity for music). Maybe we’ll never know. Hume, writing before Darwin, certainly didn’t.
Yet what has become increasingly evident in recent years is that Hume also missed a trick. For his “propensity of mankind towards the marvellous” is not confined only to the supernatural and paranormal, and nor does it couple itself only with religious impulses. It can also get married to politics and various secular causes – with some pretty worrying results.
For it seems plain that the same bug in our mental code that Hume identifies underpins a great deal of conspiracy theorising, much of which has in recent years taken on pronounced political dimensions, usually exacerbated and heightened by tribal polarisation. Take, for example, three of the most notable conspiracy theories of the past couple of decades.
- Jet fuel does not burn sufficiently hot to melt steel girders, therefore what really brought the Twin Towers down was not two jumbo jets smashing into them, but bombs put there by the CIA as part of a plot by the US government against its own people.
- A global paedophile network of Hollywood actors, members of the Democratic Party and Marxist intellectuals, led by Hilary Clinton, traffics children through the websites of online furniture stores, and keeps them locked up in the basements of pizza shops in Washington D.C.
- Bill Gates and other sinister billionaires faked a global pandemic and crashed the global economy so that they could trick people into being injected with microchips, so as to control the human population.
All three of these conspiracy theories are, plainly, absurd. Perhaps they are not, in Hume’s phrase, strictly “miraculous”, insofar as they don’t propose a violation of the laws of nature. But they do propose a violation of any common sense or reasonable weighing of probabilities based on what we know about the world and how it works. And yet literally tens of thousands (maybe more) of people believe in versions of the above. Not in spite of the improbability of such claims, but because of it.
Of course, the dynamics of testimony are here in play as well. Rather than getting such stories from lone holy men wandering the desert, such narratives are now blasted out constantly by groups of believers on the internet, whose testimony reinforces the shared belief in the inherently absurd. And there may be another important parallel with religion here: conspiracy theories always centre on some (malevolent) power ultimately being in control, and in a perverse way that can seem more comforting than everything just being a chaotic mess with terrible things happening for no good reason, and with no easy solution (“resist the conspirators and all will be well!”) available. I am hardly the first to notice that there is something religious about the cult-like certainty that characterises twenty-first century conspiracy theories that circulate online.
But what a Humean interpretation here suggests is that the reinforcing effects of repeat testimony, serving a quasi-religious need for explanations and meanings, could only work as effectively as they do if that bug towards embracing “the absurd and miraculous” was already present, in at least some significant proportion of people. Of course, not everybody is susceptible to the allure of the buggy code in the same ways, or to the same degree (not everybody, thankfully is a conspiracy theorist or a religious extremist). But a great many plainly, it seems, are.
If this Humean diagnosis of modern conspiracy theories is right – that what fuels them is a glitch in our mental code, one that we find throughout history and across the species – then there is at least one political lesson to draw in turn. That if you want to combat conspiracy theories that operate through appeal to the “propensity of mankind towards the marvellous”, then it will be absolutely hopeless to merely “appeal to the facts” (or as in recent discourse, “follow the science”).
For a start, if you’re perceived as a political enemy, it’s doubtful your facts will even be recognised as such by your opponents, who are motivated to view them with deep suspicion just because they come out of your mouth. But even if they did recognise your facts as facts, if the Humean diagnosis is right, then the facts won’t make a difference anyway.
After all, pointing to facts means appealing to non-buggy, non-haywire mental processing: the kind where we proportion our belief to the strength of the evidence, raising or lowering that in line with what we take the facts to be. But the “propensity towards the marvellous” works by inverting the relationship between strength of evidence and proportionate belief. So simply piling more facts on is absolutely not going to work; it’s appealing to the wrong process.
What, then, is the answer? I wish I knew, though I suspect that education has some kind of role to play. After all – as Hume was keen to remind us – we are not slaves to this bizarre “propensity to the marvellous”. We can, when we step back and coolly reflect, learn to control it, and to subordinate its strong intuitive appeal. Education – in the sense of teaching people how to be sceptical and to think carefully, i.e. not just “for themselves” (the tagline of many a conspiracy theorist) – seems, in the round, to help with this. But clearly education is neither fool proof nor a panacea. There are many well-educated conspiracy theorists (and, for that matter, many well-educated Archbishops who believe that a man called Jesus once walked on water).
This is all worth taking very seriously, however. There was a time when conspiracy theories were a bit like fringe religions: weird, but they didn’t really bother or affect anyone else. Yet in a world where armed gunmen turn up to pizza restaurants to free non-existent trafficked children, where angry followers of Q believe their democracy is being stolen from them and are prepared to storm the Capitol to prevent this, and where global pandemics are prolonged because many people fear that vaccines are a foil for control by shadowy global elites, the political and social consequences are all too real. The collision of the “propensity to the marvellous” with the internet has brought new and unexpected challenges. If we’re going to deal with such challenges, it at least helps to correctly identify their psychological underpinnings. As so often, Hume turns out to be of great help.
Paul Sagar is senior lecturer in political theory at King’s College London, and has published widely on political and moral philosophy, especially that of David Hume, Adam Smith, and Bernard Williams.
