Hume's Enquiry Concerning the Principles of Morals › The Is-Ought Problem

Buried in a paragraph of the *Treatise*, but implicit throughout the *Enquiry*, lies what may be Hume's most influential contribution to ethics: the is-ought problem. > "In every system of morality, which I have hitherto met with, I have always remarked, that the author proceeds for some time in the ordinary way of reasoning, and establishes the being of a God, or makes observations concerning human affairs; when of a sudden I am surprised to find, that instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not." The point is deceptively simple. You cannot derive a conclusion about what ought to be the case from premises that only describe what is the case. No amount of factual information, however complete, can by itself generate a moral conclusion. Something else is needed: a sentiment, a valuation, a caring about outcomes. This observation (sometimes called "Hume's guillotine") has cut through centuries of moral philosophy. It challenges any attempt to ground ethics in pure reason, natural law, divine command, or scientific fact. Each of these approaches, Hume suggests, smuggles in a hidden evaluative premise. The natural law theorist assumes we ought to follow nature. The divine command theorist assumes we ought to obey God. The scientific ethicist assumes we ought to maximize well-being or minimize suffering. But these "oughts" cannot be derived from the "is" statements that precede them. Scholars continue to debate exactly what Hume meant by this passage and how strong a claim he intended to make. Some read it as a logical point about the impossibility of deriving evaluative conclusions from purely descriptive premises. Others see it as a more modest observation about the need to make our evaluative premises explicit. Either way, the passage has shaped metaethics ever since. ::: {.callout-tip title="Practical Application"} When someone argues that you should do X because of facts Y and Z, ask yourself: what's the hidden assumption that connects these facts to this obligation? Recognizing the gap between is and ought clarifies what's really at stake in ethical disagreements. :::