How Quine's Critique of Analytic Philosophy Undermines the Is-Ought Distinction

The is-ought distinction — the thesis that no descriptive statement can entail a normative one — is typically treated as one of philosophy's most secure results. It originates with Hume's observation that moral conclusions seem to appear without logical warrant from factual premises, and it was given formal teeth by Moore's open question argument, which purports to show that "good" cannot be identified with any natural property. Together, these arguments underwrite the so-called naturalistic fallacy.

The critical insight here is that these arguments form a dependency chain with a fatal vulnerability. Hume's gap requires Moore's demonstration that evaluative predicates are non-natural. Moore's open question argument, in turn, presupposes that we can give analytic definitions of natural kinds and that there is a robust analytic-synthetic distinction — assumptions that were standard at the birth of analytic philosophy but which Quine systematically dismantled. Quine showed that the analytic-synthetic boundary cannot be drawn without circularity, and that essences are discovered empirically rather than stipulated a priori. Without the analytic-synthetic distinction, the open question argument cannot establish that goodness is categorically different from natural properties.

This does not license every naturalistic reduction of value to fact. What it does is reopen a question that has been prematurely closed. The naturalistic fallacy, far from being a logical law, was a technical prohibition resting on technical premises — premises that the subsequent development of philosophy has undermined. The relationship between descriptive and normative claims is a live philosophical problem, not a settled one.