Editing G. E. Moore (section)

====Open-question argument====
{{Main|Open-question argument}}
Moore's [[argument]] for the indefinability of 'good' (and thus for the fallaciousness in the "naturalistic fallacy") is often termed the [[open-question argument]]; it is presented in [http://fair-use.org/g-e-moore/principia-ethica/s.13 §13 of ''Principia Ethica'']. The argument concerns the nature of statements such as "Anything that is pleasant is also good" and the possibility of asking questions such as "Is it ''good'' that x is pleasant?". According to Moore, these questions are ''open'' and these statements are ''significant''; and they will remain so no matter what is substituted for "pleasure". Moore concludes from this that any analysis of value is bound to fail. In other words, if value could be analysed, then such questions and statements would be trivial and obvious. Since they are anything but trivial and obvious, value must be indefinable.

Critics of Moore's arguments sometimes claim that he is appealing to general puzzles concerning analysis (cf. the [[paradox of analysis]]), rather than revealing anything special about value. The argument clearly depends on the assumption that if 'good' were definable, it would be an [[Logical truth|analytic truth]] about 'good', an assumption that many contemporary moral realists like [[Richard Boyd]] and [[Peter Railton]] reject.  Other responses appeal to the [[Frege]]an distinction between [[sense and reference]], allowing that value concepts are special and ''sui generis'', but insisting that value properties are nothing but natural properties (this strategy is similar to that taken by [[physicalism|non-reductive materialists]] in [[philosophy of mind]]).