Mental-threshold egalitarianism, well-known examples of which include Jeff McMahan’s two-tiered account of the wrongness of killing and Tom Regan’s theory of animal rights, divides morally considerable beings into equals and unequals on the basis of their individual mental capacities. In this paper, I argue that the line that separates equals from unequals is unavoidably arbitrary and implausibly associates an insignificant difference in empirical reality with a momentous difference in moral status. In response to these objections, McMahan has proposed the introduction (...) of an intermediate moral status. I argue that this move ultimately fails to address the problem. I conclude that, if we are not prepared to give up moral equality, our full and equal moral status must be grounded in a binary property that is not a threshold property. I tentatively suggest that the capacity for phenomenal consciousness is such a property, and a plausible candidate. (shrink)

Secular arguments for equal and exclusively human worth generally tend to follow one of two strategies. One, which has recently gained renewed attention because of a novel argument by S. Matthew Liao, aims to directly ground worth in an intrinsic property that all humans have in common, whereas the other concedes that there is no morally relevant intrinsic difference between all humans and all other animals, and instead appeals to the membership of all humans in a special kind. In this (...) article, I argue that both strategies necessitate drawing a line that is both arbitrary and implausibly opens a moral gulf between individuals whose difference from one another in terms of empirical reality is entirely unremarkable, providing reasons to reject them that go beyond the standard objections in the literature. I conclude that, if all humans are to be included in the community of equals, we must lay to rest the idea that we can do so without also including a wide range of non-human animals. (shrink)

There are few moral convictions that enjoy the same intuitive plausibility and level of acceptance both within and across nations, cultures, and traditions as the conviction that, normally, it is morally wrong to kill people. Attempts to provide a philosophical explanation of why that is so broadly fall into three groups: Consequentialists argue that killing is morally wrong, when it is wrong, because of the harm it inflicts on society in general, or the victim in particular, whereas personhood and human (...) dignity accounts see the wrongness of killing people in its typically involving a failure to show due respect for the victim and his or her intrinsic moral worth. I argue that none of these attempts to explain the wrongness of killing is successful. Consequentialism generates too many moral reasons to kill, cannot account for deeply felt and widely shared intuitions about the comparative wrongness of killing, and gives the wrong kind of explanation of the wrongness of killing. Personhood and human dignity accounts each draw a line that is arbitrary and entirely unremarkable in terms of empirical reality, and hence ill-suited to carry the moral weight of the difference in moral status between the individuals below and above it. Paying close attention to the different ways in which existing accounts fail to convince, I identify a number of conditions that any plausible account of the wrongness of killing must meet. I then go on to propose an account that does. I suggest that the reason that typically makes killing normal human adults wrong equally applies to atypical human beings and a wide range of non-human animals, and hence challenge the idea that killing a non-human animal is normally easier to justify than killing a human being. This idea has persisted in Western philosophy from Aristotle to the present, and even progressive moral thinkers and animal advocates such as Peter Singer and Tom Regan are committed to it. I conclude by discussing some important practical implications of my account. (shrink)