Did St. Thomas Aquinas Justify the Transition from 'Is' to 'Ought'

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0. A Short History of the Problem
Argument.” In order to show that good is indefinable, Moore uses as an example “one
of the more plausible definitions of good,” namely that,
to be good may mean to be what we desire to desire. Thus if we apply this definition
to a particular instance and say ‘When we think that A is good, we are thinking that
A is one of the things we desire to desire,’ our proposition may seem quite plausible.
But if we carry the investigation further, and ask ourselves, ‘Is it good to desire to
desire A?’ it is apparent, on a little reflection, that this question is itself as intelligible,
as the original question, ‘Is A good?” – that we are, in fact, now asking for exactly the
same information about the desire to desire A, for which we formerly asked with
regard to A itself. But it is also apparent that the meaning of this second question
cannot be correctly analyzed into ‘Is the desire to desire A one of the things which we
desire to desire?’: we have not before our minds anything so complicated as the
question ‘Do we desire to desire to desire to desire A?’ Moreover any one can easily
convince himself by inspection that the predicate of this proposition – ‘good’ – is
positively different from the notion of ‘desiring to desire’ which enters into its
subject: ‘That we should desire to desire A is good’ is not merely equivalent to ‘That
A should be good is good.’ It may indeed be true that what we desire to desire is
always also good; perhaps, even the converse may be true: but it is very doubtful
whether this is the case, and the mere fact that we understand very well what is meant
by doubting it, shews clearly that we have two different notions before our minds
(PE, 13). 37
According to Moore, the same argument works against every other naturalist
foundational proposal. Another example he gives is the identification of good with
pleasure. If we accepted that “x is good” is equivalent to “x is pleasure,” we would be
forced to accept a tautology, because saying “pleasure is good” we would say no more
than “pleasure is pleasure.” Such a definition, says Moore, does not inform us whether
this something that we desire to desire, is good, because we can still ask whether what
we desire to desire is good. Thus, the question whether it is good remains “open.”
Moore also considers definitions of goodness that hinge upon the notions of more
evolved and more unified, and make the same conclusion: the question remains open. 38
If the question remains open no ethics can be constructed on this foundation.
37 Hutchinson comments: “It is breaking no new ground to point out that Moore’s presentation of the
OQA is quite muddled. In fact, it is shocking how slapdash he is with something he considers so
important” (Hutchinson, p. 29). “Actually, no version of the OQA can establish the indefinability of
good as something certain” (ibid., p. 33, note 41). “Because of all it requires, the OQA is hardly
something we have a right to accept at the beginning of philosophical investigation. … He seems to be
saying that he proved to us that good is indefinable simply by getting us to see that it is!” (ibid., p. 34).
“Finally then, Moore’s ‘argument’ is not an argument, but a means for the attainment of an epiphany.
… The recognition of a question’s significance sets the stage for the epiphany that finally comes
without the obfuscating mediation of reflection. … So Moore’s project becomes one more in a very
long line of attempts to return us to, and keep us in, a state of innocence” (p. 35). See also Alexander
Miller’s analysis of this argument and its relevance today: An Introduction to Contemporary
Metaethics (Cambridge: Polity Press, 2003), p. 10-25.
38 In an article which intends to sum up 20 th century ethics, we can read that “it has been known for the
last fifty years that Moore discovered no fallacy at all. Moreover, Moore’s accident-prone deployment
of his famous ‘open question argument’ in defending his claims made appeal to a now defunct