This paper focuses on the epistemic significance of disagreement for a specific kind of contractualist (not contractarian) moral theory. I argue that a purely hypothetical version of contractualism excludes a prima facie attractive conciliationist view of disagreement simply because of the way it constructs the moral point of view. There is no room, in such an approach, for rational, hypothetical peer disagreement within the monological deliberative procedure itself. Attempts to supplement this monological procedure with a kind of post hoc appeal to actual disagreement undermine the basic rationale for adopting a hypothetical approach in the first place. An actual agreement approach to contractualism, by contrast, is well-positioned to take disagreement seriously. For such an approach, moral disagreement signals a failure to fully validate or constitute a binding norm, one that may produce – rather than merely result from – genuine moral indeterminacy. Furthermore, as each of our positions within contractualist discourse reflects a defeasible conviction about what could be the subject of genuine, intersubjective agreement among all affected, when we encounter disagreement that is not subject to clear defeaters, we do indeed have grounds to think our convictions may be mistaken, or that we must modify our credences in ways that reflect the risks we consciously run in defending and acting on convictions that do not enjoy justificatory completion.

Ethics’ reputation for wide-ranging, interminable disagreement, coupled with conciliationism regarding disagreement, has been leveraged as a basis for moral skepticism. The focus of this essay is on this challenge as it has been applied to philosophical ethics. I call the empirical conjecture underwriting the challenge into question – namely, that disagreement is widespread and roughly balanced within ethics – by describing the results of two studies involving over 400 moral philosophers. The studies reveal widespread agreement, and even consensus, on a range of purportedly contentious moral issues – capital punishment, abortion, eating meat, physician-assisted dying, euthanasia, and many others. The evidence the studies provide suggest that the extent of disagreement within ethics that the conciliationist challenge relies upon likely does not exist.

Moral naturalists are often said to have trouble making sense of inter-communal moral disagreements. The culprit is typically thought to be the naturalist’s metasemantics and its implications for the sameness of meaning across communities. The most familiar incarnation of this metasemantic challenge is the Moral Twin Earth argument. We address the challenge from the perspective of analytic naturalism and argue that making sense of inter-communal moral disagreement creates no special issues for this view.

Hobbes believed that the state of nature would be a war of all against all. Locke denied this, but acknowledged that in the absence of government, peace is insecure. In this paper, I analyse both accounts of the state of nature through the lens of classical and experimental game theory, drawing especially on evidence concerning the effects of punishment in public goods games. My analysis suggests that we need government not to keep wicked or relentlessly self-interested individuals in line, but rather to maintain peace among those who disagree about morality.

Moral disagreement is sometimes thought to pose problems for moral realism because it shows that we cannot achieve knowledge of the moral facts the realists posit. In particular, it is ‘fundamental’ moral disagreement—that is, disagreement that is not due to distorting factors such as ignorance of relevant nonmoral facts, bad reasoning skills, or the like—that is supposed to generate skeptical implications. In this paper, we show that this version of the disagreement challenge is flawed as it stands. The reason is that the epistemic assumptions it requires are incompatible with the possibility of fundamental disagreement. However, we also present an alternative reconstruction of the challenge that avoids the problem. The challenge we present crucially invokes the principle that knowledge requires ‘adherence’. While that requirement is usually not discussed in this context, we argue that it provides a promising explanation of why disagreement sometimes leads to skepticism.

In large, impersonal moral orders many of us wish to maintain good will toward our fellow citizens only if we are reasonably sure they will maintain good will toward us. The mutual maintaining of good will, then, requires that we somehow communicate our intentions to one another. But how do we actually do this? The current paper argues that when we engage in moral responsibility practices—that is, when we express our reactive attitudes by blaming, praising, and resenting—we communicate a desire to maintain good will to those in the community we are imbedded in. Participating in such practices alone will not get the job done, though, for expressions of our reactive attitudes are often what economists call cheap talk. But when we praise and blame in cases of moral diversity, expressions of our reactive attitudes act as costly signals capable of solving our social dilemma.

Complicity in an immoral, and even criminal, activity, such as robbery or murder, is itself regarded as involving responsibility for those acts. What should the position be of health professionals who are expected to participate in actions that they believe are morally wrong? Professional responsibilities may clash with private conscience. Even referring a patient to someone else, when what is in question may be assisted suicide, or euthanasia, seems to involve some complicity. This is a live issue in Canada, but similar dilemmas occur elsewhere. Physicians and others should not be coerced into involvement of any kind in what they regard as wrong. Such coercion goes against the very principles of liberal democracy. Conscience matters. Reasonable accommodation should be given to those whose moral judgment may be at variance with prevailing professional norms. Moral questions should still be given weight within medicine, and disagreements respected. Dedication to the promotion of human welfare should be paramount, but it should be recognized that there may be different visions of what such welfare consists of.