The branch of ethics that discusses the meaning and indeed the validity of the word good is called Meta-ethics, meaning ‘beyond' ethics lies ethical language. From here there are two separate branches, cognitive; where "goodness" can be known as an analytic (Moore) or synthetic (naturalists like Mill) property of the world and non-cognitive; where "goodness" cannot be know as a property of the world. Within the non-cognitivists are another group called emotivists, they uphold the view that the word good is merely an expression of feeling. I partially agree with the emotivists view that moral statements are merely an expression of feeling, but I also think that as the ‘good is so exceedingly ambiguous' (Stevenson) that any of the meta-ethical theories have validity to them. Emotivism says that moral statements merely express positive or negative feelings; it is mainly based on better to say, "it's an empirical tradition which stems from..." the work of the Scottish philosopher and empiricist Hume and the idea of Hume's fork. "When you pronounce any action or character to be vicious, you mean... you have a feeling or sentiment of blame." - David Hume. This idea was taken forward by A.J. Ayer who also believed that moral statements were primarily expressions of emotion, hence Emotivism, his theory has been called Hurrah-Boo theory An example of this is to imagine you and a friend are at a football game supporting different teams. When one team scores you cheer and your friend boos. According to this view, saying ‘euthanasia is right' is the same as saying ‘Hurrah for euthanasia!' This is the belief, called logical positivism, that any genuine truth claim must be able to be empirically tested and as moral judgements can't be tested they aren't genuine truth claims and therefore are only expressions of emotion. However, there are a few problems with Ayer's argument.