Concepts and properties in Moore's open question argument

In the case of this post, I want to stress that any feedback is welcome and encouraged. I am currently looking into G.E. Moore's so-called open question argument. A fuller discussion of the argument than what I present here is in the works. If you would like to take a look at the fuller discussion, please let me know.

In his Principia Ethica, first published in 1903, G.E. Moore famously claims that goodness is not identical with any natural property. He defends this claim with what has come to be called the “open question argument”. In this post, I claim that the open question argument rests upon a substantive and potentially controversial assumption about the relationship between concepts and properties. I then briefly consider how one might defend this assumption against one major objection. 

The name “open question argument” is somewhat misleading; Moore himself never uses the expression “open question”. What philosophers call the open question argument is first stated by Moore in §13 of the Principia Ethica. There Moore notes that, for any natural property P, the question “Is what is P good?” is “intelligible”. Thus, some scholars, such as Caj Strandberg (2004, 181), argue that, for Moore, an “open question” is an “intelligible” question. However, Moore does not base his argument on the claim that the question “Is what is P good?” is “intelligible”. Instead, Moore bases his argument on the claim that, for any natural property P, the question “Is what is P good?” does not have the same meaning as the question “Is what is P P?”, in the sense that “good” and “P” correspond to different “notions”, i.e. concepts. From this, he concludes that goodness is not identical with any natural property. Thus, we can reformulate the open question argument as follows: for any natural property P, the concept of goodness is not identical with the concept of P; therefore, goodness is not identical with any natural property.

Thus reformulated, the open question argument clearly relies on the following implicit premise:

The Non-Identity Principle: If the concept of property F is not identical with the concept of property G, then F and G are themselves not identical.

Notice that the Non-Identity Principle could not be generalized to apply to objects in general: it is not true that, if the concept of object X is not identical with the concept of object Y, then X and Y are themselves not identical. For example, consider water and H₂O. People had the concept of water long before they had the concept of H₂O, so the concept of water is distinct from the concept of H₂O. Yet water and H₂O are identical. Thus, if the Non-Identity Principle is true, then it reveals a major difference between properties and other objects. In my opinion, the Non-Identity Principle may be the most philosophically interesting part of Moore’s open question argument.

However, the Non-Identity Principle faces a major objection. Consider the property of being water and the property of being H₂O. As Thomas Hurka (2010) points out,[1] these properties appear to be identical, since water is H₂O. And now the Non-Identity Principle faces a problem. As we have noted, the concept of water is not identical with the concept of H₂O. Thus, we seem to have a case where two properties are identical, even though the concepts of those properties are not. And so we seem to have a counterexample to the Non-Identity Principle.

However, I think that the Non-Identity Principle’s proponent has a good defense available. It is not at all clear that the property of being water is identical with the property of being H₂O. For example, suppose we interpret the term “water” as meaning, roughly, “wet, transparent, tasteless stuff found in lakes, rivers, etc.” Then the property of being water would be the property of being wet, transparent, tasteless stuff found in rivers, streams, etc. Now, something could instantiate this property without being H₂O. Therefore, the property of being water would seem not to be identical with the property of being H₂O.

But let’s try to give the water-H₂O objection a run for its money. What analysis of the term “water” would make this objection plausible? Well, the property of being H₂O is the property of having the chemical structure H₂O. And we discovered that chemical structure by studying the stuff found in lakes, rivers, etc. So let’s say that the term “water” means “whatever has the same chemical structure as the stuff in lakes, rivers, etc. in the actual world”. Then the property of being water would be the property of being whatever has the same chemical structure as the stuff in lakes, rivers, etc. in the actual world. This at least makes it plausible that the property of being water is identical with the property of being H₂O.

Even on this analysis of the term “water”, however, it is not clear that the two properties are identical. The property of being water is the property of being whatever has the same chemical structure as the stuff in lakes, rivers, etc. in the actual world. The property of being H₂O is the property of having the chemical structure H₂O. It is true that these two properties occur together. Indeed, they occur together necessarily. Yet this does not yet mean that the properties are identical, and I see no way (without begging the question) to prove that they are identical. Hence, the water-H₂O objection turns out to be inconclusive against the Non-Identity Principle.

I have only scratched the surface of what could be said for and against the Non-Identity Principle. But I hope I have shown that it is one of the more interesting aspects of the open question argument.

References:

Hurka, Thomas, "Moore's Moral Philosophy", The Stanford Encyclopedia of Philosophy (Summer 2010 Edition), Edward N. Zalta (ed.), URL = <http://plato.stanford.edu/archives/sum2010/entries/moore-moral/>.

Moore, G.E. Principia Ethica. Cambridge: Cambridge UP, 2000. (First published 1903.)

Strandberg, Caj. “In Defence of the Open Question Argument”. The Journal of Ethics 8.2 (2004): 179-96.

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[1] Here Hurka gives a variation on a common objection to the open question argument: it is not an analytic truth that water is H₂O, yet the property of being water seems to be identical to the property of being H₂O. Hurka aims this objection at Moore’s claim that, if “good” and “P” have different meanings, then goodness is not identical with property P. However, Hurka—like the other interpreters of Moore whom I have read—does not seem to explicitly recognize the Non-Identity Principle underlying this Moorean claim.