Explain the fact-value distinction and Hume's is-ought gap, and assess the naturalistic fallacy and challenges to a sharp separation

What this dot point is asking

SEAB wants you to explain the distinction between facts and values, the related is-ought gap identified by Hume, and the naturalistic fallacy identified by Moore, and then to assess whether fact and value can really be sharply separated. This is the gateway issue of the ethics area: how you answer it shapes whether you think there can be moral knowledge at all. Your task is to state the distinction and its classic defences, and to weigh the challenges to a sharp separation.

The answer

Facts and values, descriptions and prescriptions

A factual or descriptive claim says how things are: water boils at a certain temperature, most people fear death. A value or normative claim says how things ought to be, or evaluates them as good or bad, right or wrong: we ought to keep promises, cruelty is bad. The fact-value distinction is the claim that these are fundamentally different kinds of statement. Descriptive claims are answerable to observation; normative claims seem to involve something more, an evaluation or prescription that observation alone does not settle.

Hume's is-ought gap

Hume noticed that writers often proceed through factual claims about what is and then, suddenly, slip into claims about what ought to be, without explaining the transition. His point is logical: you cannot validly derive a normative conclusion from purely descriptive premises, because the conclusion contains an evaluative term (ought) that appears nowhere in the premises, and a valid argument cannot have in its conclusion what is wholly absent from its premises. To reach an ought you need at least one evaluative premise. This is the is-ought gap, and as a point about validity it is widely accepted.

Moore's naturalistic fallacy

G. E. Moore made a related point about defining good. The naturalistic fallacy is the alleged error of identifying goodness with some natural property, such as being pleasant or being desired. Moore's open-question argument supports this: for any proposed natural definition of good, say "good means pleasant," it remains a sensible, open question to ask "this is pleasant, but is it good?" If the definition were correct, the question would be closed (like asking "this is a bachelor, but is he unmarried?"). Since the question stays open, good is not identical to any natural property, so values cannot be reduced to facts.

Challenges to a sharp separation

The distinction faces challenges. The most important comes from thick ethical concepts such as cruel, courageous, generous and just. These seem to be descriptive and evaluative at once: to call an act cruel is both to describe it (deliberate infliction of suffering) and to condemn it, and you cannot cleanly peel the evaluation off the description. If thick concepts entangle fact and value, then a sharp metaphysical dichotomy between the two looks doubtful. A further challenge holds that facts about human flourishing or harm constrain what can count as a reasonable value, even if they do not strictly entail value conclusions.

Separating two claims

The careful position distinguishes two different theses that are often run together. The first is the logical is-ought gap: from purely factual premises alone, no normative conclusion validly follows. This stands. The second is a metaphysical dichotomy: facts and values are utterly distinct domains with no overlap. This is more questionable, because thick concepts show the two can be entangled in our actual moral language. So one can accept Hume's logical point while denying a clean metaphysical separation, and this nuance is what strong essays exploit.

Examples in context

Example 1. From a statistic to a policy. A report states that a city's crime rate has risen (a fact) and concludes that the city ought to expand its police force (a value). The conclusion does not follow from the statistic alone: it needs an evaluative premise about how society should respond to crime, and an empirical one that more police reduces crime. The example shows the is-ought gap in everyday policy reasoning, where a hidden evaluative premise does the real work.

Example 2. The thick concept of cruelty. Describing a punishment as cruel does two things at once: it reports a feature (it inflicts gratuitous suffering) and it condemns it. Try to separate the pure description from the evaluation and the concept seems to lose its point. This is the standard illustration that thick concepts resist a clean fact-value split, which is why they are the leading challenge to a sharp separation even for those who accept Hume's logical gap.

Try this

Q1. State Hume's is-ought gap as a point about valid inference. [6 marks]

• Cue. No normative conclusion (ought) validly follows from purely descriptive premises (is), because a valid argument cannot contain in its conclusion an evaluative term absent from its premises; an evaluative premise is needed.

Q2. Explain Moore's open-question argument and what it is meant to show. [8 marks]

• Cue. For any natural definition of good (good is pleasant), it stays a sensible open question to ask "it is pleasant, but is it good?"; if the definition were correct the question would be closed, so good is not identical to any natural property.

Q3. Explain how thick ethical concepts challenge a sharp fact-value separation. [6 marks]

• Cue. Concepts like cruel and just are descriptive and evaluative at once and cannot be cleanly split into a pure description plus a separate evaluation, suggesting fact and value are entangled in moral language.