I was wondering whether the idea that goodness cannot be defined and is just intuitively recognisable when observed, still holds significant weight? It seems somewhat similar to Plato's idea of goodness in the sense that we know it when we see it but we cannot perfectly describe in our world.

It may be true that all things which are good are also something else, just as it is true that all things which are yellow produce a certain kind of vibration in the light. And it is a fact, that Ethics aims at discovering what are those other properties belonging to all things which are good. But far too many philosophers have thought that when they named those other properties they were actually defining good; that these properties, in fact, were simply not "other," but absolutely and entirely the same with goodness. (Principia, § 10 ¶ 3)

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    I tweaked the claim to constrict the ask to focus on contemporaneous professional philosophers, and hopefully stave off objections about opinions.
    – J D
    Apr 4, 2022 at 14:36
  • From the perspective of some linguists, the Natural Semantic Metalanguage posits that GOOD is a semantic prime, one of the universal and irreducible basic building blocks of meaning. Apr 5, 2022 at 4:35

2 Answers 2


The irreducibility of normativity is a mixed bag nowadays. There are intuitionists like Michael Huemer or Robert Audi(?) who I think advance the thesis tout court, but otherwise it still does show up in veiled forms. For example, start out from part of the SEP gloss of metaepistemology:

Terence Cuneo’s (2007) defense of metaepistemological realism also comes in the service of a further objective, in Cuneo’s case, a defense of metaethical realism. Cuneo’s master argument is as follows:

  1. If moral facts do not exist, then epistemic facts do not exist.
  2. Epistemic facts exist.
  3. So, moral facts exist.
  4. If moral facts exist, then moral realism is true.
  5. So, moral realism is true (Cuneo 2007: 6)

Now piece this together with a claim that the concept of knowledge is itself irreducible, and you have a recipe for a Moore-Ross deontic irreducibility claim, too.

Still, for all that, the stronger your irreduction, the more absurd-seeming your gloss of deontic concepts. Rawls puts it like so (A Theory of Justice, 1999 ed., pg. 418):

Ross holds that the sense of right is a desire for a distinct (and unanalyzable) object, since a specific (and unanalyzable) property characterizes actions that are our duty. ... But on this interpretation the sense of right ... resembles a preference for tea rather than coffee... to make it regulative of the basic structure of society is utterly capricious...

So note that there is still room for discursive reflection on even irreducible deontic concepts: Prichard found space to argue over what the irreducible property of rightness attaches to, saying that it was not possible actions directly, but the agents who are under obligation, to which the predicate of obligation intrinsically applies.


1.) Moore does not present a definition of „good“. His new idea is to take the property „good“ as an irreducible basic term. Hence it cannot be defined.

That’s common use in axiomatizing a mathematical theory: One does not define the basic terms. Instead one gives axioms which fix the relation between the basis terms.

Hence I am sceptical that Moore considers „good“ a property that is just intuitively recognisable when observed. Where does he make a similar statement?

2.) The situation concerning Plato : Also Platon does not define the idea of the good. All he does is to present a simile, namely the simile of the sun. Comparing the good with the sun which nourishes everything and makes things visible, he says about the good:

Now, that which imparts truth to the known and the power of knowing to the knower is what I would have you term the idea of good, […] (The Republic, VI, 508e,1-3)

3.) There is an ongoing discussion on the meaning of „good“ between cognitivist and non-cognitivist positions. The question is a main topic of metaethics. A classical introduction and survey of this field is „William Frankena: Ethics.“ See also


with further references.

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