Words with nonpejorative technical uses and nontechnical pejorative uses

There are some words which have both a technical meaning in some field of study and a pejorative meaning that is more widely known.  A notorious example is “Negro,” which now tends to be used as a slur in colloquial English but which physical anthropologists still use because none of the alternatives captures the meaning they need to express.  Another example would be “cult.”  In the study of religion, “cult” is the rites and practices of a particular group.  A scholar of religion could refer to any faith group as having a “cult” in this sense and be confident that no one would take offense.  Of course, there’s also the pejorative sense of “cult,” a sect considered false or extreme. 

The word “essentialism” is at the head of a whole category of examples.  Some philosophers hold that each entity in the universe has a number of qualities, that some of these qualities are more important to the entity than others, and that human reason is capable of distinguishing the more important qualities from the less important ones.  This view is called essentialism.  Essentialism in this sense is a perfectly respectable philosophical position, and from the days of Plato and Aristotle down to the present it has consistently commanded the allegiance of many eminent thinkers.  Few would claim that these thinkers have proven beyond doubt that essentialism is true, but it is certainly plausible.  Indeed, while virtually anyone who has read a little Plato can put up a reasonable case for essentialism, it takes a considerable philosophical background to make a sensible case against it. 

The same word is used in a different, though related sense.  Many postmodernist thinkers use the word “essentialist” as a sort of curse word.  In their parlance, “essentialist” often seems to mean something like “stereotyped” or “inattentive to details.”  The “essentialism” they invoke seems to be an image of a person who slaps hasty definitions on categories, assigns other people to those categories, and proceeds to interact with the people as if the only qualities they had were those that defined the categories to which they were assigned.  So, someone who decides to equate “ukuleleist” with “weirdo who doesn’t want to grow up” might meet someone who plays the ukulele and insist on always and only treating that person as a weirdo who doesn’t want to grow up.  Sociologists among you will be reminded of the role of labeling in social relationships, but I think you can see that this use of the word “essentialism” is a gross caricature of the philosophical position I sketched above. 

The names of many philosophical schools and positions have been subjected to this kind of semantic shift.  So the ancient Epicureans argued that pleasure was a positive good; their opponents transformed their name into a synonym for “gourmand.”  The Stoics argued that a right understanding of nature’s laws would free the mind from fear; now we say “stoic” when we mean “unemotional.”