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Jan Eisner Professor of Archaeology, Comenius University in Bratislava; Author, The Artificial Ape
Polythetic Entitation

When is a wine glass not a wine glass? This question fascinated the archaeological theorist David Clarke in the late 1960s, but his elegant solution, critical for a correct conceptualization of artefacts and their evolution over time, is shamefully ignored. Understanding polythetic entitation opens the door to a richer view of the built world, from doors to computers, cars to chairs, torches to toothbrushes. It is a basic analytical tool for understanding absolutely anything that people make. It indicates limits to the idea of the meme, and signals that it may be reasonable to consider the intentional patterning of matter by Homo sapiens as a new, separate kind of ordering in the universe.

Celebrating the end of our archaeological excavation season, someone tops up my glass with wine . . . except it is not a glass. That is, it is not made of glass; it is a clear plastic disposable object, with a stem. Nevertheless, when I put it down on a table to get some food and then cannot find it, I say, "Who took my glass?" In this context, I am effectively blind to its plasticness. But, with the situation transposed to an expensive restaurant and a romantic evening with my wife, I should certainly expect my glass to be made of glass.

Clarke argued that the world of wine glasses was different to the world of biology, where a simple binary key could lead to the identification of a living creature (Does it have a backbone? If so, it is a vertebrate. Is it warm blooded? If so, it is a mammal or bird. Does it produce milk? . . . and so on). A wine glass is a polythetic entity, which means that none of its attributes, without exception, is simultaneously sufficient and necessary for group membership. Most wine glasses are made of clear glass, with a stem and no handle, but there are flower vases with all these, so they are not definitionally-sufficient attributes; and a wine glass may have none of these attributes—they are not absolutely necessary. It is necessary that the wine glass be able to hold liquid and be of a shape and size suitable for drinking from, but this is also true of a teacup. If someone offered me a glass of wine, and then filled me a fine ceramic goblet, I would not complain.

We continually make fine-tuned decisions about which types of artefacts we need for particular events, mostly unconscious of how category definitions shift according to social and cultural contexts. A Styrofoam cup could hold wine, mulled wine, or hot soup, but a heat-proof, handled punch glass would not normally be used for soup, although it would function just as well. Cultural expectations allow a Styrofoam cup to be a wine glass at a student party but not on the lawn at Buckingham Palace; a wine glass in a Viennese café is often a stemless beaker, which would be unusual in London, where it would be read as a water- or juice-glass. And a British mulled wine glass in a metal holder, transposed to Russia, would not formally or materially differ from a tea glass to use with a samovar.

Our cultural insider, or emic, view of objects is both sophisticated and nuanced, but typically maps poorly onto the objectively measurable, multidimensional and clinal formal and material variance—the scientific analyst’s etic of polythetic entitation. Binary keys are no use here.

Asking at the outset whether an object is made of glass takes us down a different avenue from first asking if it has a stem, or if it is designed to hold liquid. The first lumps the majority of wine glasses with window panes; the second groups most of them with vases and table lamps; and the third puts them all into a super-category that includes breast implants and Lake Mead, the Hoover dam reservoir. None of the distinctions provides a useful classificatory starting point. So grouping artefacts according to a kind of biological taxonomy will not do.

As a prehistoric archaeologist David Clarke knew this, and he also knew that he was continually bundling classes of artefacts into groups and sub-groups without knowing whether his classification would have been recognized emically, that is, in terms understandable to the people who created and used the artefacts. Although the answer is that probably they did have different functions, how might one work back from the purely formal, etic, variance—the measurable features or attributes of an artefact—to securely assign it to its proper category? Are Bronze Age beakers, with all their subtypes, really beakers, and were they all used for the same purposes? Were they "memes" of one another, like the sort of coded repeatable information that enables the endless reproduction of individual computer-generated images? Or were some beakers non-beakers, with a distinct socially-acceptable deployment?

Clarke’s view clashes with the common-sense feeling we have about wine glasses having an essential wineglassness. Granted, there can be a Platonically-ideal wine glass if we so wish, but it is specific to times and places, as well as contextual expectation. Currently, the heartland territory of the wine glass is dominated by transparent stemmed drinking vessels made of real glass, but such memic simplicity blurs towards the multidimensional edges of the set as attribute configurations trend towards the sweet-points that mark the core, but never at-once-both-sufficient-and-necessary, attributes we expect in our classic ideas of cultural and technological objects. Clarke noted that the space–time systematics of polythetic attribute sets were extraordinarily complex, patterned at a level beyond our immediate grasp.

So the memic turns out simply to be the emic, a shorthand description only, and not part of a valid analytic once our cultural insider knowledge is removed. For the prehistoric archaeologist, the absence of such knowledge is axiomatic. Determining which attributes had original cultural salience, why and how, is endlessly challenging. Those who attempt it without polythetic entitation are flailing in the dark.