Final answer:
Sir William David Ross gave the first fully developed account of traditional Duty Theory, recognizing prima facie duties that are not absolute or equally important.
Step-by-step explanation:
Sir William David Ross gave the first fully developed account of traditional Duty Theory. He believed that earlier moral theories, such as utilitarianism and deontology, were too simplistic and failed to account for our common experience of morality. Ross proposed a moral theory that recognized prima facie duties, which are moral commitments that are not absolute or equally important. These duties include fidelity, reparation, gratitude, promotion of aggregate good, and non-maleficence.