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. Just because something is morally justifiable, such as abortion, doesn't mean that we passionately support its practice as he suggests in ‘Hurrah-boo theory' as well as this, this argument is self-refuting. It claims that "Any genuine truth claim must be able to be tested by sense experience." But this claim itself can't be tested by sense experience. So, by its own standard, logical positivism can't be a genuine truth claim. In contrast to the logical positivists and emotivists are duty based ethics, such as Kantian ethics. Kant believed that morality did not rest on sense experience as Hume would suggest but instead through a priori reason, as ethical principles aren't empirical like an act utilitarian would state but instead are necessary truths for rational beings. Kant not only believed that emotion had no part to play in the meaning of the word ‘good' but also in the way in which the ‘good' was brought about. ‘The good will shines like a jewel for its own sake.' - Kant. Kant believed that the absolute moral good derived from the categorical imperative had to be acted out purely out of ‘duty for duties sake,' we should have no ulterior motive to do good other then it being the right thing to do, emotion contradicts with this virtue. Similarly, divine command theorists would state that what is good is what is commanded by God, and we should follow these laws out of our duty to God commands. I do not fully agree with the duty based ethics view on morality that it should be purely out of duty, I personally agree more with Hume's assumption that ‘reason is the slave of the passions' and that the addition of an emotive force behind our morality makes it more virtuous then purely ‘duty for duties sake.' However, another cognitive ethical perspective for a moment that contradicts both Kant and Emotivism is Utilitarianism. On face value utilitarianism could seem quite similar to Emotivism or logical positivism, as what is morally good is what provides the most pleasure to the greatest number, pleasure being an emotion in most peoples opinions that is good.