What is the open-question argument?

The open-question argument is a philosophical argument introduced by G. E. Moore in 1903 to refute the idea that goodness can be equated with any non-moral natural or supernatural property. By demonstrating that any identity claim between goodness and properties like pleasure remains an open, meaningful question rather than a tautology, Moore argued against ethical naturalism. This suggests that moral facts cannot be reduced to simple observable properties.

What we know

• The open-question argument was put forward by British philosopher G. E. Moore in section 13 of Principia Ethica in 1903. [1, 2]
• The argument uses a modus tollens structure to show that if a property like pleasure were identical to goodness by definition, asking whether pleasure is good would be a meaningless closed question. [2]
• Because questions like "I know that it is pleasurable, but is it good?" are open and informative rather than uninformative tautologies, Moore concluded that goodness cannot be analytically reduced to natural or supernatural properties. [2]

Where to go next

• whoWho was G. E. Moore?
• the bigger pictureWhat is ethical naturalism?
• compared withHow does expressivism view moral language?
• how it workedWhat is the structure of a modus tollens argument?
• a case in pointWhat was published in Principia Ethica?
• an unexpected connectionHow does begging the question differ from an open question?While the open-question argument relies on meaningful substantive questions to refute ethical definitions, the fallacy of begging the question involves circular reasoning where an argument's premises presuppose its conclusion.

Sources

• [1]open-question argument (Wikidata Q7095717) · CC0 1.0
• [2]Open-question argument · CC BY-SA 4.0
• [3]Begging the question · CC BY-SA 4.0
• [4]Expressivism · CC BY-SA 4.0
• [5]Open question · CC BY-SA 4.0