This book argues that morality is broader and more diverse than its human manifestation. By examining core moral concepts from the hypothetical perspective of machine morality, it reveals that features we take to be fundamental to morality are in fact contingent on human limitation. Rather than asking whether machines can be moral, or how to make them so, this work uses machine morality as a philosophical lens to explore the conceptual boundaries of morality itself. The result is a new understanding of both the constraints that shape human moral thinking and the wider space of moral possibilities that lies beyond them. In doing so, it not only challenges unexamined assumptions in both moral theory and artificial intelligence (AI) ethics but also demonstrates how the otherness of machine morality provides an opportunity for philosophical discovery.