Naturalness (final)

In the wake of David Lewis’s seminal paper ‘New Work for a Theory of Universals’ (1983), a certain use of the word ‘natural’ has become widespread in metaphysics and beyond. In this usage, properties can be classified as more or less natural, with perfectly natural properties as a limiting case. For example, Lewis would claim that being negatively charged is much more natural than being either negatively charged or part of a spoon, and may even be perfectly natural. Some philosophers have enthusiastically taken up this way of talking, perhaps with extensions and modifications. Others regard it as marking a grave turn for the worse in contemporary metaphysics. Many others prefer to avoid it, motivated not by any settled conviction that it is a bad thing, but by the sense that if they were to employ it, they would be tying their philosophical fortunes to a piece of controversial metaphysical speculation. What is at stake in the debate between the enthusiasts and the sceptics? Frustratingly, the differences are often articulated in terms of differing attitudes. The sceptics are said to ‘reject’ the distinction between natural and unnatural properties, while the enthusiasts are said to ‘accept’ or ‘countenance’ it, and perhaps even to ‘take it as primitive’. But it is far from clear what it means to have any of these attitudes to a distinction; and in any case, autobiographical claims of the form ‘I reject/accept/take as primitive this distinction’ are not the sorts of things around which we should be structuring philosophical debates. Meanwhile, when enthusiasm and scepticism are given propositional content, there is great variation as regards how the contents are characterised. In many of the works of naturalnessenthusiasts, the only vision of the sceptical alternative that comes into view seems to involve wild claims such as that it is never the case that one thing is more similar to a second thing than to a third thing, or notoriously obscure claims to the effect that facts of this or that sort fail to be ‘objective’. On the other hand, discussions of the