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Incommensurability in ethics

DOI: 10.4324/9780415249126-L144-1
Version: v1,  Published online: 2005
Retrieved August 18, 2022, from

Article Summary

In ethics and neighbouring subjects, incommensurability has been attributed to at least three different kinds of entities, namely moral theories or traditions, abstract values, and particular bearers of value. Even when confined to a given kind of entity, ‘incommensurable’ and its cognates are used in several different senses. Moral theories or traditions have been judged incommensurable in the sense that rational agreement or disagreement between their proponents is impossible. Incommensurability of abstract values may mean that any bearer of a particular value is better than any bearer of some other value, or that all or some bearers of one value are incomparable in value to all or some bearers of another value. In either case, incommensurability of abstract values reduces to incommensurability of value bearers.

Applied to value bearers, there is one usage of ‘incommensurable’ according to which items are incommensurable if they cannot be measured on a common cardinal, i.e. interval or ratio, scale. Another usage identifies incommensurability with incomparability. Since there are competing understandings of incomparability, this usage gives rise to different notions of incommensurability. Finally, incommensurability of value bearers may be understood in terms of vagueness in the betterness relation.

Many arguments for incommensurability, understood primarily as incomparability of value bearers, have been given. Often such arguments appeal to the apparent diversity of values, or to the alleged fact that value is not amenable to ‘calculation’. The latter consideration is not, however, a cogent argument for incomparability. Two further influential arguments for incomparability are the ‘minor improvement’ argument, and the argument from ‘constitutive incommensurability’.

A further question concerns the consequences of incommensurability for ethical theory and practice. Incommensurability of moral theories or traditions appears to yield far-reaching theoretical consequences. Incommensurability of value bearers may affect the cogency of certain moral theories, as well as theories of the good. Furthermore, the possibility of incommensurable value bearers is often thought to impinge on the scope of practical rationality.

Citing this article:
Carlson, Erik. Incommensurability in ethics, 2005, doi:10.4324/9780415249126-L144-1. Routledge Encyclopedia of Philosophy, Taylor and Francis,
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