Editing Metaethics (section)

=== Non-cognitivist theories ===
[[Non-cognitivism|Non-cognitivist]] theories hold that ethical sentences are neither true nor false because they do not express genuine [[proposition]]s. Non-cognitivism is another form of moral anti-realism. Most forms of non-cognitivism are also forms of [[expressivism]], however some such as Mark Timmons and Terrence Horgan distinguish the two and allow the possibility of cognitivist forms of expressivism. Non-cognitivism includes:
* [[Emotivism]], defended by [[A. J. Ayer]] and [[Charles Stevenson (philosopher)|Charles Stevenson]], holds that ethical sentences serve merely to express emotions. Ayer argues that ethical sentences are expressions of approval or disapproval, not assertions. So "Killing is wrong" means something like "Boo on killing!".
* [[Quasi-realism]], defended by [[Simon Blackburn]], holds that ethical statements behave linguistically like factual claims and can be appropriately called "true" or "false", even though there are no ethical facts for them to correspond to. [[Projectivism]] and [[moral fictionalism]] are related theories.
* [[Universal prescriptivism]], defended by [[R. M. Hare]], holds that moral statements function like universalized [[Imperative mood|imperative]] sentences. So "Killing is wrong" means something like "Don't kill!" Hare's version of prescriptivism requires that moral prescriptions be [[Moral universalism|universalizable]], and hence actually have objective values, in spite of failing to be [[indicative]] statements with [[truth-value]]s per se.