MORAL TWIN EARTH

Abstract

Terence Horgan and Mark Timmons have recently published a series of articles where they attack the new moral realism as developed by Richard Boyd. 1 The new moral realism rests on semantics that uses some of the main ideas of the causal theory of names, especially the idea that kind terms have a or a synthetic definition, such as 'water is H20.' By arguing that moral semantics can provide us with synthetic definitions of moral terms it appears that the moral realist has just the tools she needs for naturalistic accommodations of moral realism. For example, the availability of synthetic definitions would help moral realists rebut Moore's open question argument in a fairly straightforward way. Against this Horgan and Timmons have argued that our intuitions about the semantics of non-moral language and moral language differ, and that while twin-earth semantic intuitions generate one result in Putnam's twater case, moral twin-earth fails to generate comparable results for moral terms.2 Horgan and Timmons conclude from this that the semantic norms governing the use of natural kind tem1s differ from the semantic nom1s governing the use of moral terms. I will argue that Horgan and Timmons' intuitive moral twin-earth argument fails to derail the new moral realism. Further, I will discuss Boyd's semantic theory and raise problems for it that do not rely on the use of moral twin-earth.