In 1968: Radical Protest and its Enemies (HarperCollins, 2018), Richard Vinen describes the ideals and mores of people he calls “68ers.” (He discusses the USA, France, Germany, and Britain and acknowledges that he omits Mexico, Czechoslovakia, and other parts of the world where the events of 1968 were probably more consequential.) For him, the 68ers include Black Panthers in Oakland, Maoist professors in Parisian grandes écoles, striking French industrial workers in shrinking factories, Berlin squatters, and more.

How should we define such a meaningful but heterogeneous category? A similar challenge may emerge when we try to define any religious or aesthetic movement or historical period. This is not only a scholarly but also a practical issue, because words like “68er”–or “expressionist,” or “fundamentalist”–can be used to motivate or to criticize. We should be able to assess whether such words apply.

One option is to apply a general scheme. For instance, 68ers were on the left. That statement invokes the ideological spectrum that originated in the French Revolution. But 68ers often differentiated themselves from the Old Left, and both sides in that debate claimed to be further left than the other.

One could define the spectrum independently and then use the definition to settle the question of how far left the 68ers stood–but surely they did not agree with each other. Nor would they all endorse anyone else’s definition of the ideological spectrum. They devoted considerable attention to debating issues (with their opponents and among themselves) such as race, sexuality, violence, Israel, and voting. Where specific views of these matters fall on the left-right spectrum seems hard to establish without taking a substantive political position.

Another option is to use an exogenous characteristic that is directly observable to define the category. For example, surely 68ers were college students during the year 1968–hence, early Baby Boomers. But most college students were not 68ers (by any definition of that term), and some classic 68ers were considerably older or had never gone to college. Even the founders of Students for a Democratic Society were as old as 32 (Vinen, p. 30), and many important 68ers were industrial workers.

A third option is to use concrete behavior to define the category. Maybe 68ers are those who participated in mass protests during the year 1968. But the largest protest in Paris was in support of de Gaulle and the regime. Some classic 68ers never literally protested. Probably few thought that the act of protesting defined their movement. And “1968” was not constrained by the calendar year. Vinen thinks that most of Britain’s ’68 took place during the 1970s. The “hard hat riot”–in favor of the Vietnam War — took place a bit late (May 1970) but is still part of Vinen’s narrative.

A common approach in the social sciences would be to treat “68er” as a latent construct that can be detected statistically. Imagine a survey with numerous items: “Do you have a poster of Che on your wall?” “Would you abolish prisons?” “Do you live in a commune?” “Do you like the main characters in Bonnie and Clyde?” After many putative 68ers had completed the survey, researchers would use techniques like factor-analysis to detect patterns. The data might show that an individual’s aggregate score on a small set of the questions defines the category of interest. Then we would have a reliable “68er scale.”

I think that kind of method is helpful, but it cannot be presented as innocent of concepts. We might ask about communes and Che Guevara because we already have a loose mental model of a 68er. We wouldn’t ask people their favorite flavors of ice cream. If we did, and the answer happened to correlate with the whole scale, we would treat that result that as a curiosity, not part of the definition of a 68er. But, if we asked about food and found out that 68ers ate lentils, that would be meaningful. Evidently, we must already know something about what a 68er is as we draft the survey. What is already in our minds?

My own view would build on Wittgenstein’s notion of a family resemblance. In Philosophical Investigations (67), he writes, “the various resemblances between members of a family: build, features, colour of eyes, gait, temperament, etc. etc. overlap and cris-cross in the same way.” He’s arguing that many useful words point to groups of objects that need not all share any single feature but that tend to share features from a list, much as a surname can point to a cluster of people who tend to display some of the same physical characteristics. (“Lots of the Joneses have curly red hair.”) Statistical procedures like cluster analysis can point to these resemblances.

But we know why physical features recur in families: DNA. Why would certain musical choices, political opinions, recreational drugs, hairstyles, and career choices cluster to form the group that we identify as 68ers? Is there an underlying cause?

I think of it this way: Each person holds many beliefs and values. Ideas come and go, and individuals hold them with various degrees of confidence. But ideas are not independent of each other. People think one thing and conclude something else as a result, thus linking two of their beliefs with a reason. For example, they might start by liking Joan Baez and come to oppose the Vietnam War, or vice versa. But there are many ways to put ideas together, and few do it in just the same way. You could hold a strongly anti-authoritarian premise that takes you to anarchism or to capitalism. You could begin by opposing the Vietnam War and find yourself against capitalism or against the state. (I’ve known some Boomer libertarians for whom Vietnam was the formative experience.)

Thus a group like the 68ers (and many others) consists of a cluster of people with a family resemblance, but the reasons that connect their individual beliefs and values together tend to recur, and they recur for discernible reasons. In that sense, a satisfactory account of the group is a list of many of their common specific beliefs and values plus a discussion of the ways that they tend to fit together. The resulting map will not describe everyone but it will capture some of the common patterns and explain on what basis members of the group disagree with each other.

See also: Levine, P. (2024). People are not Points in Space: Network Models of Beliefs and Discussions. Critical Review, 1–27 (2024). https://doi.org/10.1080/08913811.2024.2344994