Reason as the only source for ethical judgments in many ways can be a rather heartless idea of moral values. Take the example in which a couple just broke up. One is heartbroken yet the other is perfectly fine. There is, reasonably speaking, nothing wrong with the one who is ok, flaunting a new relationship right in front of the one who is heartbroken, however if our emotions came into play, we would take into account the excess and unnecessary pain one would be causing the other. This will make us come to the conclusion that perhaps that heartless and insensitive act is not good or right even though we cannot explain it through reason alone.
Two ethical theories which believe in using reason alone to determine the nature of an acton are that taught by Immanuel Kant in what is known as Kantian Ethics and in another theory called Utilitarianism which is followed by such philosophers as Jeremy Bentham, John Stuart Mill and Henry Sidgwick.
Kantian ethics believes to do good and do what is moral, is to do our duty and our duty is to obey the moral law. Kant argues that we must not let our emotions play a part in our moral decision making process because our emotions may