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What does Moore’s open question argument actually prove, and what is the standard reply to it?

Emeka Anyaoha Fellow
· 4 replies
Meta-ethicsAnalyticMedieval ChristianModern EuropeanNatural lawDavid HumeG. E. MooreGottlob Frege#is-ought#moral-naturalism#naturalistic-fallacy#open-question-argument
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Moore's open question argument from Principia Ethica (1903) keeps coming up as I work through ethics on my own, and I cannot tell whether it is a deep insight or a trick.

Here is my understanding. Take any proposed definition of good in natural terms, say “good means what promotes happiness”. Then ask: “This promotes happiness, but is it good?” Moore says that question is still open; a competent speaker can sensibly wonder about it. But if “good” just meant “promotes happiness”, the question would be like asking “this promotes happiness, but does it promote happiness?”, which is closed. So good is not the same as promoting happiness, and the same move works against any natural definition. Good is simple and indefinable.

My physics training tells me there must be something wrong with this. People once could sensibly ask “this is water, but is it H₂O?”. It was an open question for a long time. And yet water is H₂O.

So my questions:

  1. Is that the standard reply, or am I missing something?
  2. Is the open question argument the same as Hume's point that you cannot get an ought from an is? People seem to use “naturalistic fallacy” for both.
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4 answers

Accepted answer

  1. Ana Clara Ferreira

    ✓ Accepted answer Fellow

    You have found the standard reply, Emeka, and it goes back to Frege's distinction between sense and reference. “Water” and “H₂O” have different senses, different ways of presenting a thing, so the question whether water is H₂O is informative and open. But they refer to the same substance. Moore's argument shows at most that “good” and “promotes happiness” differ in sense. It does not show that they cannot pick out the same property.

    That reply was developed by naturalist realists who say goodness may be a natural property discovered a posteriori, like water's chemical make-up. So the argument is good against analytic definitions (claims about what the word means) and much weaker against metaphysical identities (claims about what the property is).

    What survives, many think, is something subtler: the persistent openness of the question suggests that moral concepts have a distinctive role in guiding action that natural concepts lack. Expressivists build on that. But as a refutation of naturalism, the argument needs that extra premise.

    1. Emeka Anyaoha

      Fellow

      This is clear now. So Moore shows that “good” is not a synonym for any natural term, and the water case shows that does not settle what goodness is. Hume makes a separate point about inference. I think what bothered me was hearing three different arguments under one label. Thank you, Ana Clara especially.

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Other answers

  1. Alistair Gow

    Fellow

    On your second question: they are different, though related. Hume's famous paragraph at the end of the first section of Book 3 of the Treatise complains that writers move from statements about what is to statements about what ought to be without explaining how. That is a point about inference: no set of purely factual premises seems to entail a moral conclusion. Moore's is a point about meaning or identity: good cannot be defined in natural terms. You can accept Hume's and reject Moore's, and many naturalists do.

    Helpful · 1
  2. Ikechukwu Anyanwu

    Fellow

    And a word on the phrase “naturalistic fallacy”, which is regularly thrown at natural law theory. Aquinas does not argue from “humans tend to do X” to “X is good”. The first precept of natural law, that good is to be done and pursued and evil avoided, is for him self-evident, and the basic human goods are grasped as goods by practical reason, not deduced from biology. Whether that escapes Hume is debated among Thomists themselves, but it is not the crude fallacy it is often accused of.

    Helpful · 2