The aim of this article is to explore John Henry Newman's reflections on the meaning of the medical profession in a lecture to medical students in Dublin. Specifically, it will show how Newman's exposition of what we have called the ″medical fallacy″ allows us to consider him as an authoritative interlocutor in the debate on the naturalistic fallacy and the indefinition of the good, led by David Hume and Georg Edward Moore. Thus, in times of COVID-19, euthanasia and emotivism, delving into the thought of the English author can contribute to illuminating the bioethical problems of our time.