Does the “Incommensurability Thesis” Imperil Common Sense Moral Judgments?

American Journal of Jurisprudence 37:1 (1992).

The distinguished legal philosopher, R. George Wright, has recently explored the implications for free speech jurisprudence of the debate among moral philosophers about the “incommensurability” of values. Wright’s analysis suggests that contemporary natural law theorists (and others) who defend the “incommensurability thesis” hold (or, for the sake of consistency, should hold) that choices between rationally grounded options are necessarily arbitrary. He has argued, for example, that my own defense of the proposition that basic values are incommensurable commits me to the proposition that, under ordinary circumstances, there cannot be a conclusive moral reason for choosing to interrupt “one’s recreational coffee drinking in order to rescue one’s friend from a painful accidental death.” In a private communication, Professor Wright has asked how I and other defenders of the incommensurability thesis can maintain that thesis while at the same time holding that someone faced with a choice between, say, risklessly saving a tot’s life and spending an extra hour on the golf course should, ordinarily, save the tot’s life.

Wright fears that strict adherence to the incommensurability thesis imperils our common sense belief that sometimes people are morally bound to choose one practical option over a competing option despite the fact that the competing option is itself rationally grounded (i.e., grounded in a basic human value). He supposes that we must admit some commensurability of values in order to save the common sense belief. I shall argue that Professor Wright’s fear is unwarranted and his supposition mistaken. The incommensurability thesis is perfectly consistent with the non-arbitrariness of morally significant choices. Hence, we may adhere strictly to the incommensurability thesis, as I think we should, without abandoning the common sense belief that many choices between rationally grounded practical possibilities admit of right and wrong answers.

I begin with a few clarifications. Wright marshals the common sense belief that choices between rationally grounded possibilities for action are often non-arbitrary against what he describes as “the broad assertion that disparate values . . . are [in] commensurable.” In referring summarily to “disparate values,” however, he neglects to take note of a distinction that is strictly respected by prominent defenders of the incommensurability thesis, namely, the distinction¬†between non-basic (e.g., instrumental) and basic (i.e., intrinsic) values. Intrinsic values, such as human life and health, friendship, knowledge, and skillful work and play, are incommensurable because they provide ultimate reasons for choice and action, i.e., reasons whose intelligibility as motives for action are not derivative of other, more fundamental reasons. Basic values, inasmuch as they provide ultimate reasons for action, are irreducible to one another or to some common underlying factor. Any value that is reducible to some more fundamental value is not a basic value; any reason for action whose intelligibility is derivative of some more fundamental reason is not an ultimate reason for action. By contrast, purely instrumental values, such as money, which provide reasons for action only as means to, or conditions for, the realization (or fuller realization) of more fundamental values, are not ultimate reasons for choice and action. Hence, they are nonbasic.

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