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Adams’ Open-Question Argument Against Ethical Naturalism


In the second chapter of his impressive book Finite and Infinite Goods: A Framework for Ethics, Robert Merrihew Adams offers an interesting variation on G. E. Moore’s famous open-question argument against ethical naturalism.[1] Adams, following Moore, takes ethical naturalism to be, “roughly, the view that ethical terms signify natural properties that are or will be mentioned in the best development of the natural sciences, including psychology and the other social sciences” (p. 58). Assuming that naturalists were in the business of giving reductive analytic definitions of ethical terms, Moore famously objected that since such analyses could always be intelligibly questioned, they could not be true by definition (Principia Ethica, Section 13). Though Adams grants that the argument fails[2], he claims that it contains an important element of truth which he expresses as follows:

  • “[A]llowing empirical reasoning of the causal explanatory sort to have the last word [in ethical inquiry] is incompatible with a [critical] stance that is essential to ethical thinking and some other important types of evaluative and normative thinking” (p. 77).
  • “The [critical] stance amounts to at least this. For any natural, empirically identifiable property or type of action that we or others may regard as good or bad, right or wrong, we are committed to leave [sic] it always open in principle to raise evaluative or normative questions by asking whether that property or action-type is really good or right, or to issue an evaluative or normative challenge by denying that it is really good or right” (p. 78).
  • “[T]o treat the value of any natural object or action, or … the value of any human consensus, as immune to [evaluative or normative] criticism is a fearful abridgment of ethical possibility. In a religious perspective, it is idolatry” (p. 78).

But this version of the open-question argument, like similar critiques of ethical naturalism[3], seems to be deeply confused.

In the first place, much the same critical stance is surely essential to modern science as standardly conceived, and it can hardly be said to be incompatible with giving causal-explanatory empirical reasoning the last word in scientific inquiry![4] Even our best scientific theories could–epistemically speaking–turn out to be false.

In the second place, ethical naturalists can and (influenced by empirical science) generally do adopt a fallibilist perspective in moral epistemology: they deny that certainty is achievable and insist on the rational revisability of each ethical judgment.[5] Even our best ethical theories, they would say, could turn out to be false.[6] So they can hardly be committed to treating some ethical judgments as immune to criticism.

Adams would probably reply that I am missing the point, that the real issue is whether an ethical theory that–by agreement of all parties–fully and uniquely met scientific standards of empirical justification could still intelligibly be criticized. And he insists that it could and that ethical naturalists must deny this.[7] But in fact it is easy for naturalists to accommodate such criticism: they need only maintain that a critic of the empirically justified ethical theory would have a substantively mistaken view of epistemic justification in ethics. Again, the analogy with science is helpful: a scientific theory that–by agreement of all parties–fully and uniquely meets scientific standards of epistemic justification can still intelligibly be criticized, except perhaps by someone who accepts those very standards as applied to whatever topic is under discussion. Indeed, critics of science have often raised such criticism when scientific theories conflict–in reality or perception–with their cherished beliefs about religion, creation, the soul, or what have you.

In the third place, given the array of thoughtful arguments Adams musters on behalf of his own divine-command theory of morality[8], he evidently regards it as superior (especially in explanatory value) to its rivals. Why doesn’t his version of the open-question argument, then, imply that he has thereby abandoned the critical stance essential to ethical thinking and “fearfully abridged ethical possibility”? Contrary to what Adams suggests[9], at this point it is not enough to appeal to the glaring imperfection and fragmentariness of our knowledge of the transcendent God on whom morality supposedly depends. For ethical cognitivists of all kinds–nontheistic as well as theistic–can and should agree that our moral knowledge is inevitably imperfect; and fallibilists in particular are as entitled as Adams to insist on the verification-transcendence of moral truth.[10] Moreover, Adams is not in a good position to claim that our moral knowledge is fragmentary; for his articulation of the divine-command theory requires (quite reasonably) that the divine commands on which moral obligation is supposedly based have been genuinely communicated to us.[11]

I conclude that Adams’s version of the open-question argument against ethical naturalism is no more successful than the original version of Moore, and that if it did work it would undercut his own ethical supernaturalism.


[1] Oxford: Oxford University Press, 1999. A review of this book I wrote earlier this year for www.infidels.org indicates what I take to be some of its many virtues and some of its flaws.

[2] “The fact that the correctness of an analysis can be intelligibly questioned,” he notes, “does not show that the analysis is not correct” (Finite and Infinite Goods, p. 78). Given his familiarity with the work of Richard N. Boyd and Nicholas L. Sturgeon (see sections 2.2-2.4), it is initially surprising that Adams does not mention here the chief response of contemporary ethical naturalists to the open-question argument: namely, that their theories do not depend on analyses of the meaning of ethical terms. See, for example, Nicholas L. Sturgeon, “Moral Explanations” in Morality, Reason and Truth: New Essays on the Foundations of Ethics, ed. by David Copp and David Zimmerman (Totowa, NJ: Rowman and Allanheld, 1985), pp. 58-62, 73, 75n15-16, and “Gibbard on Moral Judgments and Norms” in Ethics 1985, pp. 25-26. Also see Richard N. Boyd, “How to be a Moral Realist” in Essays on Moral Realism, ed. by Geoffrey Sayre-McCord (Ithaca, NY: Cornell University Press, 1988), p. 199. Perhaps the omission is merely due to the fact that Adams gives his version of Moore’s argument after discussing Sturgeon’s nonreductive naturalism and in the course of discussing Boyd’s nonreductive naturalism.

[3] Adams acknowledges his debt here “to broadly similar critiques of causal explanatory criteria for ethical truth in [Thomas] Nagel, The View From Nowhere, [Oxford, Oxford University Press, 1986,], pp. 144-46; in [David] Copp, “Explanation and Justification in Ethics,” Ethics, 1990]; and especially in unpublished work of Sigrun Svavarsdottier” (p. 78n). His version is also somewhat reminiscent of the well-known moral twin Earth argument of Mark Timmons and Terry Horgan; see Ch. 2 of Timmons’s Morality Without Foundations: A Defense of Ethical Contextualism (Oxford: Oxford University Press, 1998). I criticize the Timmons/Horgan argument in a work in progress called “Moral Twin Earth Revisited,” but do not regard it as deeply confused.

[4] Unless, of course, there is no “last word” in scientific inquiry, as fallibilists may insist. (I return to fallibilism in the next paragraph of the text.) And if there isn’t, then ethical naturalists aware of this fact will and should insist that there is no last word in ethical inquiry either.

[5] For example, see pp. 67-71 of Sturgeon’s “Moral Explanations” for a Quinean approach that suggests fallibilism.

[6] To be sure, ethical naturalists who accepted a Peircean or ideal-justification account of moral truth might not wish to say this. But then, like Peirceans regarding scientific truth, they would need to be persuaded that a suitably critical stance requires the fallibility even of ideally justified belief. I can find no real argument in Adams to this effect.

[7] Finite and Infinite Goods, pp. 79-81.

[8] Finite and Infinite Goods, esp. Chs. 10-11.

[9] Finite and Infinite Goods, pp. 81-82.

[10] Moreover, this inconsistency problem is especially troublesome for Adams given the role played in his arguments by a priori, analytic–and thus presumably objectively certain and rationally unrevisable–claims about morality (Finite and Infinite Goods, pp. 234, 236). I discuss these claims in my online review.

[11] Finite and Infinite Goods, section 3.3. See section 3.4 for more on divine commanding, and 15.3-15.4 on general vs. special revelation.

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