The reason, he says, is that the apparent consensus about libertarianism that emerged in the 1970s and started unraveling by the 1990s was just a temporary condition—an anomaly; libertarianism has otherwise been a shifting, evolving movement suffering "recurring bouts of fragmentation and re-fragmentation."

Libertarianism has no "fixed philosophical essence," Zwolinski says, or you wouldn't have seen the drastic swings in how the term was applied between Déjacque's anarcho-communism of the 1850s and Leonard Read's free markets and limited government of the 1950s, let alone the present-day. There simply has never been a permanent, stable paradigm of liberty.

Yes, an apparent consensus was arrived at in the 1970s in the "rights-based free-market" views of Robert Nozick, Ayn Rand, and Murray Rothbard—which Zwolinski also tellingly labels as rationalist and absolutist. (Code-word alert: he means unempirical and dogmatic, which are bad things, unlike the empirical and flexible approach he favors.) But this was more of a historical accident, or perhaps a breathing spell, before society in general and libertarian theory in particular began a steady unraveling and loss of cohesion.

And now we have a half dozen or so factions all claiming a spot under the "big tent" of libertarianism: bleeding-heart libertarians with their interest in social justice and the possibility of wealth redistribution and racial reparations, left-libertarians and their critique of "actually-existing capitalism" (not just the mixed economy of government favors and regulations, but also "boss"-run businesses), paleolibertarians getting cozy with right-wingers, tech-right, neo-reactionaries aligned with Peter Thiel and Elon Musk—and, of course, the aging remnant of the Nozick-Rand-Rothbard axis that wonders why the others don't see true nature of liberty the way they do.

As Zwolinski explains, the reason why the rationalistic, absolutist champions of rights and free markets just don't get it is that they fail to realize that libertarianism isn't a cohesive system of ideas but instead is a sociological phenomenon, explained by what he refers to as "tribalism." He applies to libertarianism the framework described by Hyrum and Verlan Lewis in their book The Myth of Left and Right, in which they claim that "left" and "right" are tribes, "not coherent ideologies," and that they "don't hang together because of any underlying philosophical essence," but "because they happen to be the positions currently held by the left-wing and right-wing tribes."

A number of things must be said about this "tribal," sociological analysis of political shifting and about Zwolinski's prescriptions of how to make peace with it. First of all, there's the idea already noted that libertarianism should be a "big tent" under which all the various "tribes" of claimants to the title can live and work together. Multiple tribes—under one tent? Whoever heard of such a thing! Perhaps neighboring villages, but one big tent?