Online research in philosophy

It is widely believed that Twin-Earth-style thought experiments show that the contents of a person's thoughts fail to supervene on her intrinsic properties. Several recent philosophers have made the further claim that Twin-Earth-style thought experiments produce metaphysically necessary conditions for the possession of certain concepts. I argue that the latter view is false, and produce counterexamples to several proposed conditions. My thesis is of particular interest because it undermines some attempts to show that externalism is incompatible with privileged access.

In Chapters 4 and 5 of his 1998 book From Metaphysics to Ethics: A Defence of Conceptual Analysis, Frank Jackson propounds and defends a form of moral realism that he calls both ‘moral functionalism’ and ‘analytical descriptivism’. Here we argue that this metaethical position, which we will henceforth call ‘analytical moral functionalism’, is untenable. We do so by applying a generic thought-experimental deconstructive recipe that we have used before against other views that posit moral properties and identify them with certain natural properties, a recipe that we believe is applicable to virtually any metaphysically naturalist version of moral realism. The recipe deploys a scenario we call Moral Twin Earth.

(1) Is content in the head? I believe that water is wet. My twin on Twin Earth, which is just like Earth except that H2O is replaced by the superficially identical XYZ, does not. His thoughts concern not water but twin water: I believe that water is wet, but he believes that twin water is wet. It follows that that what a subject believes is not wholly determined by the internal state of the believer. Nevertheless, the cognitive similarities between me and my twin are striking. Is there some wholly internal aspect of content that we might share?

In a series of articles, Terry Horgan and Mark Timmons have argued that Richard Boyd’s defence of moral realism, utilizing a causal theory of reference, fails. Horgan and Timmons construct a twin Earth-style thought experiment which, they claim, generates intuitions inconsistent with the realist account. In their thought experiment, the use of (allegedly) moral terms at a world is causally regulated by some property distinct from that regulating their use here on Earth; nevertheless, Horgan and Timmons claim, it is intuitive that the inhabitants of this world disagree with us in their moral claims. Since any disagreement would be merely verbal were the alleged moral facts identical to or constituted by different natural facts, the identity or constitution claim must be false. I argue that their argument fails. Horgan and Timmons’ thought experiment is underdescribed; when we fill out the details, I claim, we shall see that the challenge to moral realism fades away. I sketch two possible interpretations of the (apparently) moral claims of the inhabitants of moral Twin Earth. On one interpretation, they fail to disagree with us because they actually agree with us; on the other, they fail to disagree with us because they are not moralizers at all. Which interpretation is true, I argue, will depend on the facts that explain the differences between us and the inhabitants of moral twin Earth.

In this paper I argue against Twin-Earth externalism. The mistake that Twin Earth arguments rest on is the failure to appreciate the force of the following dilemma. Some features of things around us do matter for the purposes of conceptual classification, and others do not. The most plausible way to draw this distinction is to see whether a certain feature enters the cognitive perspective of the experiencing subject in relation to the kind in question or not. If it does, we can trace conceptual differences to internal differences. If it doesn’t, we do not have a case of conceptual difference. Neither case supports Twin Earth externalism.

In order to rebut G. E. Moore’s open question argument, ethical naturalists adopt a theory of direct reference for our moral terms. T. Horgan and M. Timmons have argued that this theory cannot be applied to moral terms, on the ground that it clashes with competent speakers’ linguistic intuitions. While Putnam’s Twin Earth thought experiment shows that our linguistic intuitions confirm the theory of direct reference, as applied to ‘water’, Horgan and Timmons devise a parallel thought experiment about moral terms, in order to show that this theory runs against our linguistic intuitions about such terms. My claim is that the Horgan–Timmons argument does not work. I concede that their thought experiment is a good way to test the applicability of the theory of direct reference to moral terms, and argue that the upshot of their experiment is not what they claim it is: our linguistic intuitions about Moral Twin Earth are parallel to, not different from, our intuitions about Twin Earth.

Hilary Putnam's Twin Earth thought experiment has come to have an enormous impact on contemporary philosophical thought. But while most of the discussion has taken place within the context of the philosophy of mind and language, Terence Horgan and Mark Timmons (H8cT) have defended the intriguing suggestion that a variation on the original thought experiment has important consequences for ethics.' In a series of papers, they' ve developed the idea of a Moral Twin Earth and have argued that its significance is that it has the resources to undermine naturalistic versions of moral realism.' H8t T don't hold back in their assessment. "Moral Twin..

A number of philosophers defend naturalistic moral realism by appeal to an externalist semantics for moral predicates. The application of semantic externalism to moral predicates has been attacked by Terence Horgan and Mark Timmons in a series of papers that make use of their “Moral Twin Earth” thought experiment. In response, several defenders of naturalistic moral realism have claimed that the Moral Twin Earth thought experiment is misleading and yields distorted and inaccurate semantic intuitions. If they are right, the intuitions generated by Moral Twin Earth cannot be appealed to in arguments against externalist moral semantics. The most developed case against the Moral Twin Earth argument that follows this strategy is found in a paper by Stephen Laurence, Eric Margolis and Angus Dawson. Here I argue that their attack on the Moral Twin Earth thought experiment fails. Laurence, Margolis and Dawson have not shown that we have reason to distrust the semantic intuitions it generates.