Abstract

Plato’s Socrates says in the Phaedrus that we should “cut up each kind according to its species along its natural joints, and to try not to splinter any part, as a bad butcher might” (265e). In the Statesman Plato’s interlocutors make the similar suggestion that kinds should be divided from one another “limb by limb, like a sacrificial animal” (287c). This jointing metaphor is often used to illustrate the divisibility of the natural world into objective kinds or natural categories—such as into particles like electrons, species, such as Homo sapiens, or even into sociological kinds like care-giver or psychological ones like fear. It has been thought that by dividing the world at its joints, we can lay bare the natural kinds; when we fail to so divide we splinter the world’s kinds like an incompetent butcher. In accordance with the metaphor, each bone in the animal body is likened to a category of things in the natural world. The claim that there is one natural set of joints at which we can physically separate the parts of the animal parallels the claim that there is a unique set of natural categories into which we should partition objects into species. Some, such as David Hull, say that this metaphor is “apt” (Hull 1989, 153) and others, like Ian Hacking, that it is “unsavory rubbish” (Hacking 1991, 111). Philip Kitcher is equally critical, writing that: “Plato gave us a vivid metaphor, suggesting that our classificatory task is like that of carving a beast at its joints. But that is just metaphor. I find it hard to give substance to the notion that nature is a beast with joints or that it comes with neat fenceposts that our scientific language must respect.”.