As you’ll have noticed, there’s an awful lot of stupidity afoot in the world. To take the obvious example, consider the principle the journalist Josh Marshall calls “Trump’s razor”, after the philosophers’ rule known as Occam’s razor: when trying to decode the president’s actions, the stupidest explanation you can think of is always likeliest to be true. It’s sometimes argued that we should be grateful for stupid leaders, since at least their stupidity makes life less hazardous: imagine if they were sufficiently focused and clever to implement their worst ideas! But that wasn’t the view of the late Italian economist Carlo Cipolla. In 1976 he published a tongue-in-cheek essay that’s been gaining new attention in the age of Trump. The Basic Laws Of Human Stupidity makes the alarming case that stupid people are by far the most dangerous.

Cipolla has a technical definition of a stupid person: someone “who causes losses to another person [or group] while himself deriving no gain and even possibly incurring losses” – as opposed to a “bandit”, who pursues selfish gain at cost to others. “Day after day, with unceasing monotony, one is harassed in one’s activities by stupid individuals who appear suddenly and unexpectedly in the most inconvenient places and at the most improbable moments,” he writes. Part of the problem is that we assume that certain kinds of people – educated people, powerful people, suit-wearing professionals, people we agree with politically – can’t be stupid. In fact, Cipolla insists, stupidity arises equally in all segments of the population. But the non-stupid never grasp this, so they’re doomed to be surprised, over and over: “Always and inevitably everyone underestimates the number of stupid people in existence.”

What makes stupid people so dangerous is that you can’t refer to their own self-interest to predict or explain their actions. “An intelligent person may understand the logic of a bandit,” Cipolla writes. “The bandit’s actions follow a pattern of rationality: nasty rationality, if you like, but still rationality.” Not so with the stupid. (Some of Trump’s policies seem calculated to benefit him personally, but many don’t: why cause pointless diplomatic rifts, or go to such lengths to look as guilty over Russia as possible?) The perverse result is that stupidity has power – and stupid people gain a foothold – because the usual rules of strategy don’t apply. “Because of the erratic behaviour of the stupid, one cannot foresee all the stupid’s actions and reactions, and before long one will be pulverised by the unpredictable moves of the stupid partner.”

There’s an icy kind of comfort in a world run by villains, a fact that may explain the appeal of conspiracy theories: they help us feel that there are grownups in charge, even if they’re evil. Stupidity offers no such consolation. It’s unsettling to realise that any given terrible news development might serve no one’s best interests. And that our efforts to understand what’s going on, or what might happen next, are virtually guaranteed to fail – because we’re trying to puzzle out the rules of the game, when the real problem is that there aren’t any.

oliver.burkeman@theguardian.com