As I’m writing this post, Jeremy Corbyn has been elected leader of the British Labour Party. Bernie Sanders is pulling ahead of Hillary Clinton in the Democratic primary in New Hampshire. (She is still trying hard to pass as a friendly grandmother, apparently not succeeding). Donald Trump leads in the Republican primary, as he hops around the country in his private plane which has his name emblazoned on its side (so we know who is coming, about to spout politically-incorrect obscenities). Each of these developments was totally unpredicted and defies rational explanations.

Jeremy Corbyn (age 66) was elected with a large mandate (facilitated by a rule that anybody could vote right away in the leadership election regardless of any previous memberhip in the party, by just paying a small registration fee—sort of like getting entrance to a members-only club by paying at the door). Corbyn has been in politics for a long time, proudly located on the far Left of the Labour Party. His focus will be on “inequality”. He advocates a bevy of Leftist policies—heavy taxes on “the rich”, renationalizing public utilities, unilateral nuclear disarmament, pulling the UK out of NATO (possibly out of the EU as well), and supporting the Palestinian cause against Israel (he called Hamas and Hezbollah his “friends”). All experts agree that with this platform he could not possibly be elected in a general election. (Are they sure?) His most immediate foe is New Labour—the term used by former prime minister Tony Blair when he pulled the party to the center from the fever swamps of the Left. Corbyn has explained his (rather neat) beard as a protest against New Labour.

Bernie Sanders (age 74) seems like an American cousin of Corbyn’s. He is an independent senator from Vermont, who votes with the Democrats in the Senate. He describes himself as a “democratic socialist” (thank you for the adjective, Senator). He too zeroes in on “inequality”, with the familiar agenda of “soaking the millionaires” (could he mean the Clintons?), expanding the welfare state, and opposing most of U.S. foreign policy (except maybe the opening toward Cuba). He too is deemed to be unelectable in a general election. Of course Republicans in the U.S. and Tories in Britain are hoping that these two men will bring about a long period of conservative rule. The hope may be premature; one ignores at one’s peril the capacity of voters to act crazy. Both men come out of closed Leftist milieus whose “red diaper babies” go through childhood with the fear of a Bolshevik uncle coming for a visit.

But then there is Donald Trump (age 69), who really is a multi-millionaire. He is almost impossible to satirize. Perhaps his historic mission is to prove that voters on the Right can go politically crazy as readily as voters on the Left. His political views are incoherent, but his theme song “Making America Great Again” resonates with the Right, as do the relatively few concrete policies he has endorsed: an aggressive foreign policy, economic measures against China and India for “ripping us off”, deporting all illegal immigrants (except the ones he calls “the good ones”), building a fence along the whole U.S./Mexico border to prevent all these “murderers and rapists” from coming in (and making the Mexican government pay for the fence). I suppose that Democratic strategists are praying that Trump will be the Republican nominee. They too may be miscalculating: On the ideological map of the U.S. there are more crazies on the Right than on the Left.

Political commentators are scrambling for rational explanations for the enthusiastic crowds that applaud every one of this unlikely trio. It was predicted that several economic developments would bring about a surge of Leftist ideas—the slow recovery from the recession and the changes in the labor market wiping out whole categories of blue-collar jobs that used to be avenues for social mobility. The return of traditional Leftist rhetoric by the Corbyn/Sanders pair could be seen as the result of fears of these developments. But then again, on both sides of the Atlantic, the same developments have fueled populist movements on the Right. Trump appeals to the latter, a distinctively American mix of “angry white men”, xenophobes and enraged motorcycle gangs. However, I would suggest that a general problem here is an over-estimation of the place of rationality in human affairs.

So-called rational actor theory has recently become prominent in the social sciences in America. It is essentially a project to explain a wide chunk of human behavior by employing concepts derived from economics. It assumes that, consciously or not, human beings decide to behave by some sort of costs/benefits calculus, as supposedly is done by an actor in the marketplace.

The theory has also been applied to religion, especially in the work of Rodney Stark. It is plausible, to a degree, when a combination of religious pluralism and religious freedom has created a sort of market situation—pre-eminently the case in America. One may of course doubt whether actors in a market really act as rationally as the theory assumes—just look at the hysterical swings on Wall Street! The concept of the rational actor is much less plausible in other religious cases. Take an individual considering whether to become an Islamist suicide bomber as a cost/benefit analysis: Cost—I’ll be killed. Benefit—I go directly to paradise and get seventy-two virgins as a reward. (I wonder whether this promise may actually serve as a disincentive for some—seven virgins maybe, but seventy-two?!)

In any case, most religious behavior is hard to fit into economic categories. Minimally, I think, one should distinguish between two types of rationality proposed by Max Weber: utility-rationality, which calculates probable outcomes (which, if anywhere, applies to economic behavior), and value-rationality, which can be very rational within the context of a specific set of moral beliefs. For example, the Talmud is a highly rational system of rules, over which there have been centuries of argumentation which trained generations of yeshiva students in razor-sharp logic—but all within a religious framework that only makes sense to someone who believes in it.

There is a curious case of a thinker who started out as an adherent of an idea of the rational actor (it wasn’t called that at the time), and then created a major work intended to refute the idea. It is the case of Vilfredo Pareto (1848-1923), an Italian scholar sometimes listed as one of the classical sociologists (though hardly any sociologist ever reads him today). He started out as an engineer, then became a prolific economist.

I don’t know when his disillusion with all this quasi-mathematical concept of rationality came about. In his early years he was a candidate for parliament, and lost. (Possible conclusion from this experience: anyone not voting for Pareto cannot be rational!) He left Italy and lived for the rest of his life in Switzerland (if there is one country with an ethos of sober rationality, this is it!). He divided human behavior as being of two types: “logical” and “non-logical” action. It is significant that the discipline of sociology was originally invented by Auguste Comte (1798-1857) under the motto “to know, in order to predict, in order to control” (an engineer’s creed if there is one). Pareto re-invented sociology as the discipline to study “non-logical action”. The massive product of this phase of his scholarship was the work commonly known as the Trattato/Treatise of General Sociology. It was published in four volumes in 1916 (he himself wrote it in both Italian and French). It is an immensely erudite and eccentric work. [My wife Brigitte Berger wrote her doctoral dissertation on Pareto, about whose theories she was skeptical but which she interpreted as an anticipation of what later became known as the sociology of knowledge.] Two key Paretian categories are “residua” and “derivations”, respectively the non-logical motives of behavior and their dubious “logicalizations” (a Freudian synonym would be “rationalizations”). Pareto lived in a charming villa on Lake Geneva, from where his wife eloped with their chauffeur. I don’t know whether this infidelity should be classified as logical or non-logical (but then I didn’t have to live with Vilfredo as he bilingually churned out his four volumes of esoterica).

I must stop now, before this post becomes a lecture on different concepts of rationality. But I would mention another concept: that of definitely irrational frenzy. I would call it the St. Vitus factor. He was a fourth-century Christian martyr, who became the patron saint of epileptics and dancers. His name has been used in modern medicine to refer to the “St. Vitus dance” (also called the “Sydenham chorea”), characterized by involuntary spasmodic movements of the body resembling a grand-mal epileptic attack. It is related to another involuntary behavior called the “Tourette syndrome”, which begins with a facial tic and is then followed by incoherent shouting (usually with obscene content). But what interests me here is not these diseases, but the cult that developed in medieval Germany around the saint’s name day. The German version of his name was Sankt Veit, so the cult celebrating him was called Veitstanz. Those engaged in this ritual were not suffering from the diseases associated with the patron saint of epileptics. But the name of the ritual can serve as a useful metaphor for various frenetic movements, especially in religion and politics.

It is intellectually and emotionally comforting to think that most human actions are rational. It makes for a more predictable and potentially controllable world. The institutions of society are typically based on rational assumptions (though not necessarily those of the engineer or the economist). Institutions are dams holding at bay the howling frenzies lurking in human souls. All institutions are fragile. Sometimes the dams break.