 Standing alone, however, both responses seem vulnerable to the claim that similarities associated with species membership may explain, but cannot justify, the treatment of all other human beings as moral equals. Why should a sense of fellowship, however strong, be a source of moral status? If our sense of fellowship reflected what mattered morally, why wouldn’t we feel greater fellowship with McMahan’s intelligent, morally sensitive Martian than with a human infant whose developmental disabilities make him apparently unresponsive to other humans?