Abstract: Can values be reduced to facts about nature? There are different forms of ethical naturalism: conceptual naturalism (that value-terms are definable in natural terms, a view that G.E. Moore famously denounced as ‘the naturalistic fallacy’) and substantive naturalism (that certain matters of value in effect come down to certain matters about the natural world). Both these forms of naturalism bring us up against the fuzziness of the notion of the ‘natural’. In this connection, the chapter considers whether values supervene on natural properties, and ends with doubts that they do. The chapter then proposes a third form of naturalism: expansive naturalism, in which the boundaries of the ‘natural’ are pushed outward a bit, in a duly motivated way, with the effect that they now encompass basic human interests and so prudential values.

Keywords: ethical naturalism, G.E. Moore, natural, naturalism, naturalistic fallacy, supervenience,