The term “essentialism” often comes up in my classes, and I always stop my students to ask what it means. It is supposed to be a bad thing to make essentialist claims, but what exactly is the problem? Perhaps an essentialist is someone who makes a claim of the form “all X’s are A”, for example, “all women are nurturing” Yet in academic work, people rarely make such categorical claims; obviously most variables, well, vary. Maybe most X’s are A, maybe more X’s are A than Y’s are A, but in the social sciences our data are almost always noisy. The sin of essentialism has to be something more than simply inaccurate generalization. But what? Maybe essentialists use dichotomies where the world is continuous; maybe essentialists use univariate models when the world is multivariate. But the accusation of essentialism seems a lot more freighted than would be the case if the problem were simply ignoring complexity. Of course the world is complex, but one has to understand the simple case first, before trying to figure out the more complicated, general scenario.
One possible concerns has to do with locally accurate but culturally and institutionally dependent generalization. If women do tend to be more nurturing, maybe it is in part because we have all internalized powerful norms about what it means to be masculine and feminine, norms up that were up until recently supported by laws that allowed men and women very different opportunities. Maybe in other actual or possible cultures and institutional settings men and women aren’t / wouldn’t be much different, with respect to nurturing. The problem here would be overgeneralization, mistaking an accurate generalization about a particular place and time for a truth about all places and times. Anti-essentialism in this sense would be closely connected with “social construction.” Those likely to put forward charges of essentialism are those who believe, with Nietzsche and Foucault, that most allegedly universal human characteristics have a historical origin (not an evolutionary origin). It also connects with older Marxist ideas about how the regular patterns we observe in social phenomena can be relative to (i.e. only hold within) particular social systems. Classical economics was not wrong, according to Marx, it was simply right about one particular system, and did not grasp the dynamic process that would lead from one system to another.
So far, the concerns about essentialism we’ve canvassed have been essentially empirical. Lots of things are socially constructed, lots of things do vary across cultures, but presumably not everything, or not to the same extent. Just how much is an open question.
However, in rejecting essentialism people may also be objecting to policies based on generalizations, even when the generalizations are accurate, and even when the generalizations are not generated by the policies in question. Consider racial profiling. People may argue that racial profiling is ineffective, that it is based on false stereotypes, and that the public awareness of the policy reinforces false stereotypes, but a further objection would be that it is wrong to impose serious costs on all people with characteristic X just because people with characteristic X are statistically slightly more likely to commit a crime. This moral objection should be familiar; Mill opposed temperance in On Liberty, despite the plausible case for restricting alcohol based on increased likelihood of harm-to-others (e.g. domestic assault, rape), because it saddled responsible drunks with the faults of the problem drinkers. It is a form of anti-utilitarian thinking, a requirement of individualized treatment.
Finally, a rejection of essentialism may involve a denial that there is one (or any) defining purpose or goal human life. Traditionally, the “essence” of something was the defining formula for a thing of that kind, which identified the characteristics of a fully developed or perfected thing of that kind. This way of thinking goes back to Aristotle and Plato, and makes some intuitive sense for tools and living creatures. In rejecting essentialism, people could be denying that claims about what makes a good or perfected human being should play any explanatory role in scientific explanation, but more likely they are denying that there is one pinnacle of human perfection. Perhaps there are many different, conflicting, but authentically good lives one can lead, displaying different, incompatible but genuinely admirable virtues. Essentialism in this sense would be objectionable because it assumes a kind of ethical monism, when in fact values are plural, and conflicting. (I suppose that anti-essentialism could involved denying that it makes any sense to talk of better and worse lives – scepticism or relativism – but I don’t find that an interesting or plausible view).
Final point: these normative forms of “essentialism” are objectionable, if they are objectionable, for familiar liberal reasons: individual responsibility and pluralism about the good. The objectionable empirical forms of essentialism are just that: perhaps true but perhaps false claims that need to be assessed based on the best evidence available.