, Volume 79, Issue 2, pp 445–460 | Cite as

Goodness and Moral Twin Earth

  • Christopher Freiman
Original Article


Terry Horgan and Mark Timmons’s “Moral Twin Earth” thought experiment allegedly undercuts virtually any form of naturalist moral realism. I argue that a neo-Aristotelian conception of moral properties defeats Moral Twin Earth. Developing themes in the work of Peter Geach, Philippa Foot, and Rosalind Hursthouse, I sketch an Aristotelian moral semantics that is unique in construing terms like ‘right’ and ‘good’ exclusively as attributive adjectives that denote relational properties. On this view, moral goodness is a relational property predicated of those human beings that satisfy kind-relative criteria of goodness; i.e., morally good human beings are good qua human being. The reference of moral terms is therefore fixed by the natural properties of human beings. This account ensures that moral facts cannot differ across worlds in which the relevant natural facts do not differ and thus defeats Moral Twin Earth.


Noun Phrase Natural Property Moral Fact Competent Speaker Natural Kind Term 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



Thanks are due to Julia Annas, Nathan Ballantyne, Matt Bedke, Jason Brennan, Ian Evans, David Schmidtz, Frans Svensson, Mark Timmons, Kevin Vallier, and an anonymous referee for this journal.


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.Department of PhilosophyCollege of William and MaryWilliamsburgUSA

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