Secular ethics is a branch of moral philosophy in which ethics is based solely on human faculties such as logic, reason or moral intuition, and not derived from purported supernatural revelation or guidance (which is the source of religious ethics). Secular ethics comprises any ethical system that does not draw on the supernatural, such as humanism, secularism and freethinking.

The majority of secular moral systems accept either the normativity of social contracts, some form of attribution of intrinsic moral value, intuition-based deontology, or cultural moral relativism. A smaller minority believe scientific reasoning can reveal moral truth. This is known as science of morality. Approaches like utilitarianism, subjective moral relativism, and ethical egoism are less common, but still maintain a significant following among secular ethicists.^{[citation needed]} Little attention is paid to the positions of moral skepticism and moral nihilism; however, many religious and some secular ethicists believe that secular morality cannot exist without a god or gods to provide ontological grounding, or is at least impossible to apprehend apart from authoritative revelation.