What is the moral significance of being human? In this dissertation, I defend the humanist doctrine known as basic equality, according to which all human beings deserve to be treated as equals: they deserve equal consideration of their interests and have equal moral rights. A growing number of philosophers (“the skeptics”) believe basic equality is false. In this dissertation, I defend basic equality against their central concern: that human beings are too different to deserve equal treatment of any kind.,Basic equality is a foundational idea of modern moral and political philosophy. For example, basic equality has been evoked to defend the test of universalizability in Kantian ethics as well a strong principle of impartiality in Utilitarian ethics. Basic equality has important political implications as well: it has been used to defend democracy and universal human rights and to explain what is wrong in wrongful discrimination. So much is at stakes when we consider whether basic equality is true. ,I start by bringing to light an assumption of the skeptical argument against basic equality: Correlationism. According to Correlationism, how individuals deserve to be treated is correlated with the extent to which they possess some morally significant property, such as rationality or autonomy or virtue. Philosophers who accept this assumption (the “Correlationists”) believe that if basic equality is true, it is because human beings equally possess some such property. If humans do not possess any such property to an equal degree, basic equality is false. So says the skeptic. ,My defense of basic equality begins by arguing that Correlationism is false. When the Correlationist argues that the way individuals should be treated is correlated with the extent to which they possess some property, she must rely, I argue, on the principle of formal equality, according to which equal cases should be treated equally and unequal cases unequally. If we can show that basic equality cannot be an instance of the more general principle of formal equality, we would show that Correlationism is false. By analyzing the ethical implications of formal equality and basic equality, I argue that basic equality is indeed not an instance of the more general principle of formal equality, and so that Correlationism is false, and the skeptical argument against basic equality fails.,Then, I turn to develop a positive account of basic equality, one that does not rely on descriptive equality for its justification. I call this account “the respect view”. On this view, basic equality is not grounded in descriptive equality but in a more fundamental ethical requirement to respect human beings. Respect, I argue, is a comparative and egalitarian attitude: If two individuals deserve respect, then treating one’s interests as less important than another’s is disrespectful to the one whose interests as treated as less important. I then argue that individuals can deserve respect even if descriptive equality is false. Last, I argue that all human beings deserve respect, despite not having any morally significant property to an equal degree. From this I conclude that despite the fact that descriptive equality is (probably) false, basic equality applies to all human beings. ,I end by considering the moral status of nonhuman animals. I argue that while some nonhuman animals might have comparable overall cognitive functioning as some human beings, and while all sentient animals have some moral rights, nonhuman animals, unlike human beings, do not deserve respect, and so basic equality does not apply to them. The upshot of the respect view, then, is that all human beings and only them deserve to be treated as equals. This conclusion stands against recent developments in applied ethics, which tend to favor the extension of basic equality beyond human beings or to restrict basic equality to a subset of human beings.