The Cartesian tradition yields a very definite conception of what value – moral, aesthetic and so on – must be. Or, rather, it yields a specific framework of possibilities for the sort of thing value must be. The view of the mind as essentially an interiority – something located entirely inside the skins of mental subjects – presents us with a stark choice when trying to understand the nature of value. Either value must derive from the inside – from the activities of the mind – or it must exist on the outside, objectively present in the world independently of those activities. Broadly speaking, the former view is known as subjectivism and the latter as objectivism. This choice between subjectivist and objectivist models of value has pretty much defined moral debate since the time of Plato.

This debate has its problems. If we opt for the idea that value is ultimately a product of the mind, understood as something located exclusively inside the skins of mental subjects, then we are quickly led to the idea that value is not really in the world at all. That is, we are driven to the view that the world, and the things in it, do not really possess value in themselves. Should the activities of the mind that constitute value cease, there would be no value; the apparent value of worldly items would dissipate. Real value, on this subjectivist model, lies on the inside; it is possessed by the outside only to the extent that the inside is able to project it outwards.