The open-question argument is a philosophical argument put forward by British philosopher G. E. Moore in §13 of Principia Ethica (1903),[1] to refute the equating of the property of goodness with some non-moral property, X, whether natural (e.g. pleasure) or supernatural (e.g. God's command).
The idea that Moore begs the question (i.e. assumes the conclusion in a premise) was first raised by William Frankena.
[4] The Darwall-Gibbard-Railton reformulation argues for the impossibility of equating a moral property with a non-moral one using the internalist theory of motivation.
On the other hand, externalism holds that moral properties give us reasons for acting independent of desire or utility.
If internalism is true, then the OQA may avoid begging the question against the naturalist by claiming that the moral properties and the motivations to act belong to different categories, and therefore, necessarily are not analytically equivalent.
That is, it remains an open question whether the properties which do give rise to certain sentiments ought to guide our actions in that way.
is intelligible and so, in that limited sense, whether or not water is H2O is an open question; note that this does not address the issue of significance.
"Water is H2O" is an identity claim that is known to be true a posteriori (i.e., it was discovered via empirical investigation).
This is done by invoking rightness and wrongness to explain certain empirical phenomena, and then discovering a posteriori whether maximizing utility occupies the relevant explanatory role.
[7] For example, they argue that since right actions contingently have certain effects e.g. being causally responsible for a tendency towards social stability—so it follows we can fix the term "right" refer to the empirical description "the property of acts, whatever it is, that is causally responsible for their tendency towards social stability.
We can then conclude that we have learned that "right" refers to "maximizing utility" through a posteriori means.
[9] A citizen living on the frontiers of the Wild West is told by the sheriff that his brother is the Masked Man who has recently been robbing banks.
The "explicit knowledge" solution comes from philosophers Mark Balaguer and Terry Horgan.
All the definition, or analysis, did, was to make explicit what the children and adults already implicitly knew about the concept of "circle".