Good is indefinable: the open question argument

The open question argument; the naturalistic fallacy

G. E. Moore 1873 · 1958Good cannot be defined by anything else: equating 'good' with 'pleasant' is a mistake.

What it claims

"good" names a simple and indefinable notion, like "yellow", which is not the same as any natural property. Confusing it with pleasure or desire is committing the "naturalistic fallacy".

Why

For any definition of good, we can still ask "but is it good?", so the question is not empty.

The same idea through history

David Hume1740Hume had already noticed that people slip without warning from what "is" to what "ought" to be, and that this step needs explaining. But Hume concluded that morality comes from feeling; Moore concludes something quite different.

G. E. Moore1903Moore, building on his teacher Henry Sidgwick (for whom "ought" cannot be analysed), holds that "good" names a simple quality that no definition can replace. He calls the mistake of confusing it with a natural property the "naturalistic fallacy".

In short

"Good is indefinable: the open question argument" is an argument by G. E. Moore (Principia Ethica, chapter I, § 6-13 (1903), 1903) on the question "What makes something right?" (answer: nature or conscience). Its claim: "good" names a simple and indefinable notion, like "yellow", which is not the same as any natural property. Confusing it with pleasure or desire is committing the "naturalistic fallacy". According to AskPhilosophy's logic check (Z3 solver), the argument is valid only if one grants a premise the author leaves unstated (P2, P4). AskPhilosophy presents 3 objections, 3 of them with a documented reply, and the original text behind each premise, checked word for word.

Principia Ethica, chapter I, § 6-13 (1903)

Valid with an implicit premise

What is good? Pleasure, say some; what we desire, say others. Moore proposes a very simple test. Take any definition, for example "good = pleasant". Then ask: "it is pleasant, but is it good?" The question makes sense, it remains open. If "good" really meant "pleasant", it would be as empty as asking "it is pleasant, but is it pleasant?". Moore's conclusion: "good" cannot be defined; it is a simple notion, like yellow. Truths about what is good in itself cannot be proved: Moore calls them "intuitions". We place the argument in this camp because, for Moore, the good is not an external command: it is known directly, by the mind.

click a premise to reject it

If you accept every premise, logic forces you to accept the conclusion. So the debate is about the premises.

Checked by a logic solver: the premises cannot all be true while the conclusion is false.
Without the implicit premise: Without P4, the computer finds a case where "good" and "pleasant" do not mean the same, yet still name the same property, like "water" and "H2O": good would then be a natural property. Without P2, it finds a case where the question remains open although the definition is correct, simply because it is not obvious.

With its four premises, the argument is valid. It rests on two hidden premises. P2 says that a correct definition never leaves an open question: that is what the "paradox of analysis" disputes. P4 moves from the meaning of words to the nature of things: that is where Putnam and Boyd attack. Moore never writes P4, but his argument needs it to conclude that good is not a natural property.

Analogy. Try explaining what yellow is to someone who has never seen it. You can talk about wavelengths, lemons, the sun: none of this is yellow itself. For Moore, "good" is like "yellow": we recognise it, we do not define it.

Objections

Each objection is a conversation: click to see who replies and where the debate stands.

C. H. Langford (the paradox of analysis) 1942 · attacks premise 2

Every successful analysis falls into a trap: if the definition has exactly the same meaning as the word defined, it teaches nothing; if it does not, it is wrong. Yet some definitions are both correct and informative. So a question can seem "open" simply because the correct definition is not obvious: that does not prove there is none.

Moore replies

Moore Moore's reply (1942)

Moore acknowledges the problem. He maintains that a correct analysis links two different expressions of one and the same concept, but he admits that he does not see clearly how to solve the puzzle.

The debate goes on (our summary) As early as 1939, Frankena charged Moore with assuming what had to be proved: saying that the question "is pleasure good?" remains open already grants that "good" and "pleasure" differ. Moore's defenders answer that the question does not stay open like a hard definition in mathematics: it stays open even for someone who knows all the facts, because "good" serves to guide our choices. It is in this form that the argument is still discussed today.

Hilary Putnam, then Richard Boyd 1981 · attacks premise 4

Moore confuses concepts and properties. "Temperature" does not mean "mean molecular kinetic energy", and yet they are the same thing: science discovered it. Likewise, "good" may not mean the same as any scientific word, without this preventing goodness from being a natural property. It would be up to inquiry to discover it, not to the analysis of words. Boyd (1988) draws from this a "naturalistic" moral realism.

Moore replies

Terence Horgan and Mark Timmons A defence of Moore's spirit: "Moral Twin Earth" (1991)

Imagine a Twin Earth where the word "good" is governed by a different natural property from ours. If goodness were a natural property like water, the people of that Earth and we would be talking about different things, and our moral disagreements would be a mere misunderstanding. Yet it would rather feel like a real disagreement. So the open question returns, in a new form.

The debate goes on (our summary) Naturalists answer that our impressions of disagreement can mislead us, as they misled us about water before chemistry. The comparison with water and temperature has a limit, though: we know how science found H2O, whereas we cannot yet see what inquiry would find the natural property "good".

A. J. Ayer (1936), then Charles Stevenson 1936 · attacks the conclusion

Moore is right to reject natural definitions of good, but wrong to appeal to intuition: what seems evident to one person seems doubtful, or even false, to another, and no test can settle it. If "good" cannot be defined, it is because it names nothing: it is a pseudo-concept. Saying "you were wrong to steal that money" is only saying "you stole that money" in a tone of disapproval. This is emotivism, the direct heir of the open question.

Moore replies

Moore Moore's reply to Stevenson (1942)

Moore makes a surprising concession. He feels some inclination to think that two men arguing about an action may only be expressing opposing attitudes, as Stevenson says. But he also still has some inclination to think that his old view was true: they assert incompatible things, one right and one wrong. He says he does not know how to decide.

The debate goes on (our summary) Emotivism has its own difficulties: if "stealing is wrong" is neither true nor false, it is hard to see how we can reason with it, for instance in "if stealing is wrong, helping to steal is wrong". This is Geach's objection (1965). The debate between those who see truths in morality and those who see attitudes remains open, and Moore's open question still serves as a weapon for both sides.