Talk 2: Defending Moral Twin Earth (7 April 2011)

Philosophy Seminar Series: 7 April 2011, 4.30 – 6pm, Philosophy Resource Room; Speaker: Mok Wan Hao Jacob, Current MA Student, NUS; Moderator: Ms Charlene K.L. Koh


In “Return to Moral Twin Earth”, David Merli puts forth three replies to the Moral Twin Earth (MTE) argument against Naturalistic Moral Realism (NMR). The MTE argument—first stated by Terry Horgan and Mark Timmons—undermines NMR by constructing a scenario wherein different speaker communities’ usage of moral terms like “good” or “right” are univocal despite picking out different natural properties—something that NMR renders implausible. Merli replies on behalf of NMR by arguing that (i) Twin Earth will have to be either too similar to or too different from Earth to have moral terms share meaning and pick out different natural properties, (ii) the moral expertise of future Twin-Earthians and Earthians with stable fully coherent moral theories (‘End-Of-Day theories’) who think that their moral terms are equivocal should prompt current Twin Earthians and Earthians to think the same, and (iii) there is a way to make sense of disagreement in the MTE scenario without giving up NMR via the notion of disagreement over the “last-ought-before-action”. I will attempt to show that Merli’s responses do nothing to scotch the MTE argument.

The presentation will have four parts. The first part (Part I) of the presentation will see the reconstruction of the MTE argument in greater detail—pointing out that much of the force of the argument rests on our semantic intuitions. In the Part II, I deal with Merli’s first reply. I argue that Merli generates a false dilemma for the MTE scenario and assumes wrongly that the content differences of moral terms in the MTE scenario must be more significant than those across cultures on Earth. In Part III, I highlight the problem with Merli’s second reply: he assumes too much in thinking that the moral expertise of future Twin Earthians and Earthians translates to semantic expertise. In the fourth and final portion (Part IV), I consider Merli’s third reply and argue that the notion of disagreement over the last-ought-before-action is helpful only if Merli’s first two replies are convincing.

JacobAbout the Speaker: Jacob Mok completed his undergraduate studies in philosophy earlier last year at the National University of Singapore with first class honours—his honours thesis being an attempt at defending the Equivalence Thesis. He is currently pursuing a M.A. in philosophy at the very same institution. His interests include the philosophy of science, moral philosophy, and normative ethics. He is fascinated with issues of theoretical confirmation and with how non-humeans about practical reason can hold what they do.

More information on the Graduate Seminar Series can be found here.

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