The serious threat to objectivity in ethics does not come from the mere existence or even the degree of ethical disagreement, but from its persistence. What leads philosophers to deny that rational justification is possible in ethics is not that people disagree about their ethical conclusions in the beginning or that they disagree so often, but that their disagreement persists even after prolonged reasoning with one another. This inability to achieve agreement by rational methods would not bother us if it were clear that some of the parties to the dispute were uninformed or irrational, but the hard fact is that eminently reasonable men may continue to disagree on ethical issues even after each has considered carefully every reason advanced by the other in support of his conclusion. When no amount of reasoning leads rational men to agree on which ethical conclusion is true, how can it still be claimed that there is an objective truth in ethics?
To begin with, it is important to recognize that this characterization of the persistence of ethical disagreement is inaccurate and misleading. It is inaccurate to say that "no amount" of reasoning leads rational men to agree on their ethical conclusions because this implies that the largest possible amount of reasoning has been completed. However, the process of rational criticism, in which reasoning is embedded, has no limit; it is an open-ended process of discussion and reflection. No matter how long this process of challenge and response has gone on, it could go on longer. It is more accurate to say that even very prolonged reasoning fails to lead rational men to ethical agreement, but even this is misleading. It is only half true that prolonged reasoning does not bring agreement. Granted that on many occasions this is true, there are many other occasions on which reasoning does produce agreement. What we actually find, then, is that some ethical disagreements persist in the face of reasoning and that some are resolved.
Does this partial persistence of ethical disagreement rule out the claim to objective truth? To claim that a statement is true, if my analysis is correct, is to claim that all completely rational men who are fully aware of all relevant considerations would agree to it after indefinite criticism. Thus the claim to truth does presuppose agreement, but the agreement it requires is an ideal agreement to emerge from the process of rational criticism carried on for an indefinite time among an indefinite number of reasoners. There is always a logical gap between the result of actual reasoning among a limited number of imperfectly rational men through a limited period of time and the ideal agreement projected by the claim to truth. Therefore, the actual persistence of ethical disagreement does not refute the claim of ethical statements to objective truth, for the agreement presupposed by this claim is an ideal agreement that might emerge if only the process of reasoning were continued farther [sic; should be "further"].
(Carl Wellman, "Ethical Disagreement and Objective Truth," American Philosophical Quarterly 12 [July 1975]: 211-21, at 212-3 [italics in original])
Note from KBJ: Wellman is correct that the actual persistence of ethical disagreement does not refute the claim of ethical statements to objective truth. The question, however, is not whether the persistence of ethical disagreement refutes the claim to objective ethical truth, but whether it renders the claim improbable or implausible. We're dealing with probabilities, not certainties. Which of the following is more likely: (1) that brilliant people over the course of two and a half millennia have been unable to discover the truth about right and wrong, good and bad, just and unjust, even though the truth is out there, waiting to be discovered; or (2) that there are no objective ethical truths? The latter, in my judgment, is far more likely. In light of this, it is ethical objectivists, not ethical subjectivists, who have the burden of persuasion. They must do more than refute arguments for ethical subjectivism. They must make arguments for ethical objectivism. I have never seen a plausible argument for ethical objectivism. What I see is a lot of bad arguments against ethical subjectivism.
Keith Burgess-Jackson, J.D., Ph.D. 