It's fairly well known that Muslim immigrants in Europe tend to support left-wing political parties, but it's not obvious why, given that Muslims tend to oppose key planks of Western social liberalism. It's even more puzzling why Western leftists so actively support the in-migration of Muslims, given that Western leftists just as actively excommunicate from their own ranks anyone who opposes key planks of social liberalism — nay, anyone who does not sufficiently profess their love for key planks of social liberalism. So then why do Muslim immigrant populations like left-wing parties, and why do Western leftists want Muslim immigrant populations, when each group hates the defining features of the other group's worldview?

Perhaps one might question the premises of this puzzle, so before I attempt a solution to the puzzle, let's go over the premise that Muslims tend to oppose key planks of social liberalism and the premise that Muslims in the West support left-wing parties.

If you think I'm exaggerating the deep ideological conflict between Islam and social-justice leftism, consider the following. One Gallup poll in 2009 found that zero of the 500 British Muslims in the sample found homosexuality "morally acceptable" — and only about half thought it should be legal (a rather low bar for social liberalism). If you look for the most generous estimates of Islamic sexual liberalism in the West, you can find about 52% of American muslims in 2017 saying that homosexuality should be accepted by society. You can find other estimates in between these two, for different countries and years in the recent past. Presumably, assimilation has some effect, so you have to imagine that new immigrants and asylum-seekers are, on average, on the lower end of these estimates.

One might also wonder if Islam really makes immigrants more likely to support left-wing parties (controlling for other factors correlated with leftism, such as youth). Maybe Muslim immigrants in Europe tend to be socially illiberal only because they are disproportionately young, uneducated, and poor. Nope. The graph below is from Piketty's recent paper on political cleavages, specifically from his discussion of the case of France, where support for left parties is 42% higher among Muslims than non-Muslims.

Those other factors do have effects, but being Muslim still has a unique positive correlation with support for left-wing parties:

More precisely, socio-economic control variables reduce the Muslim left-wing preference from +42 points to +38 points in 2012, and adding foreign origins (including separate dummies for each region of origin) further reduces the effect to +26 points (see Figure 2.6k). In other words, for given gender, age, education, income, wealth and region of origin (for instance North Africa), there is still a sizable effect associating self-reported Muslim identity and left-wing vote. One natural interpretation is that Muslim voters perceive an additional, specific hostility from right-wing parties (and/or an additional, specific sympathy from left-wing parties), as compared for instance to voters with North African origins but who do not describe themselves as Muslim. [Emphasis added. -JM] Thomas Piketty, Brahmin Left vs Merchant Right, 2018

Piketty finds the same pattern for Britain. Piketty's explanation is probably not wrong but it's rather unsatisfying. It's not the focus of his paper so don't write him rude emails expressing dissatisfaction with this explanation. It's just that... to say that Muslims like left-wing parties because right-wing parties hate Muslims, is only to rewrite the algebra. We can just as well pose our puzzle as: Why does antipathy to Muslim immigrants come in a right-wing package, when the offending Muslim viewpoints are primarily offensive to left-wing social liberalism? Right-wingers in the West might very well think, "Good! These incoming Muslim men know a thing or two about enforcing traditional gender norms and keeping out the gays! Maybe they'll rub off on us and forestall our downward spiral of degeneracy!" This sounds impossible to imagine, but that's the puzzle; why is this impossible to imagine when it's at least as plausible, and arguably more plausible, than what we are observing empirically. It sounds very implausible that someone who likes to wave a placard expressing love for brown-skinned folks who hate most queers also likes to denounce white people for only loving nine out of ten queers. And yet this occurs today. If Piketty's solution is unsatisfying, then what's a better explanation?

Wait no longer, because I have the answer. Well, a hypothesis. Which means I personally believe it is the answer (at the time of this writing).

We are accustomed to seeing today's leftist activists as extreme ideologues. The reason contemporary leftist culture is so baffling to so many people is that — it's presumed — they are overly possessed by an ideology; they are extremists on some set of principles; they are crazy because they are too radical, with respect to some set of ideas that is assumed to be underlying their speech and behavior.

Recall my article from a few months ago, analyzing the General Social Survey. I found that the anti-free-speech leftists, the most visible of left-wing activists today, are not technically more extreme leftists; rather, these 'authoritarian leftists' seem to be drawn from those who identify as only somewhat leftist. In other words, they are extreme on some dimension, but it's not leftism per se.

This dovetails with the hypothesis I would like to make here. Contemporary left-wing activists do not suffer from ideological possession or overly extreme devotion to any ideology. In fact, they lack ideology. That's the answer. The contemporary left is simply a grievance processing machine. Ideology has nothing to do with it. Ideology has as much to do with left-wing activism as Mozart has to do with the garbage disposal beneath your kitchen sink: You might hear it on their commercials, but that's about it. The inventors were not listening to it when the idea first presented itself. It plays zero role in the machine's function, which is why the machine runs perfectly fine no matter what the user happens to be listening to. This is why many left-wing activists today can hate one person for being a queer-hater and then profess love for some other queer-haters, all in the same day.

Many people will not believe my hypothesis, because it seems obvious that left-wing activists are constantly referring back to certain shared mental structures. That's true, but that's not all that ideology involves. Political scientists have long observed that vague 'worldviews' don't necessary qualify as ideologies. One of the key marks of ideology, properly understood, is constraint (Converse 1964):

"constraint" or "interdependence" refers to the probability that a change in the perceived status (truth, desirability, and so forth) of one idea-element would psychologically require, from the point of view of the actor, some compensating change(s) in the status of idea-elements elsewhere in the configuration. Philip E. Converse, The Nature of Belief Systems in Mass Publics, 1964

When I say that left-wing activists are relatively non-ideological, I am not saying that they are not possessed by certain consistent social-psychological processes; I am only saying that the main process is not primarily ideological in this technical sense, because a hypothetical change in one node of the belief-web does not require any change in any other node of the belief-web. Ideology implies a kind of automatic, mechanical updating of the belief-web, given some exogenous shock. It's this functional automaticity, taken to extremes, that makes us think of ideologues as robot people.

And there is good empirical evidence that, in fact, it's conservatives who are motivated by ideology, while leftists mostly care about group interests. See Grossmann and Hopkins (2016). In a nutshell, they look at the language used by lefties and righties when they articulate their likes and dislikes. Do they relate their likes and dislikes to certain ideas or principles, or do they refer to how different groups are affected? They find a pretty huge difference, as revealed in this graph from their 2015 paper (which pretty much speaks for itself):

This finding deserves to be better known. If there is an ideology of left-wing activists, it is that there are no principles other than getting stuff for groups who don't have as much stuff as other groups. If you fervently believe that, it can look and sound a lot like an ideology. And you can call it an ideology if you'd like — if it looks like a duck, and walks and quacks like one, then ain't it a duck?—the only problem is that this will make you baffled by all the patent logical inconsistencies. One of the reasons why leftism today is so baffling to so many people is because people expect these "ideologues" to be possessed by some set of principles, and then people burn a lot of glucose trying to infer what these principles are. To no avail.

This non-ideological ideology of left-wing activists also helps to explain why leftists love Muslim immigrants, and why Muslim immigrants vote for left-wing parties. Leftists love Muslims because Muslims have grievances that left-wing parties can profitably process for them. Why Muslims love left-wing parties should now be obvious: it's because they have grievances in need of processing, and the left-wing parties are structurally incapable of opposing, let alone stopping, anything Muslim immigrants think or do — on account of their non-ideological, i.e., unconstrained operating philosophy.