The starkest difference between the ethical theories of utilitarianism and deontology reside in that the former makes ethical decisions based upon consequences and the latter makes decisions based upon principle.
Whereas utilitarianism may ask questions such as “Does this action lead to the greatest good?” or “Will the result of this specific action be beneficial to me or to others?”, deontology asks “Am I following the law in this action?” or “ Does this action fulfill my ethical duty?”. Both of these theories have their own unique advantages and disadvantages.
Regarding advantages, the utilitarian theory is extremely accessible to diverse groups of people functioning within a pluralistic society. Since the theory defines moral behavior as that which leads to the best consequences for oneself and for others, it is possible to act with respect to one’s own and other people’s happiness regardless of other moral structures within which people operate.
For example, a Buddhist and a Christian can both act morally toward one another without relying on their own metaphysical belief structures.
In addition, by giving consideration to the ends of moral action, it is possible to avoid hurting people in order to uphold a principle: in this theory, for example, it would be permissible to lie to Nazi police about hiding Jews because the result of saving Jewish lives is greater than the consequence of telling a lie.
However, problems with this theory are abundant. The greatest problem is that it is not so easy to define what the greatest good for the most people may in fact be.
In some situations, the greatest good may be to euthanize old people or deformed babies; yet this does not seem ethically permissible. When consequences determine ethical behavior, we face the risk of overlooking the rights of the individual in order to achieve a “greater” good.
Deontological theory is advantageous in that it is able to ground ethics upon law and duty. In this framework, we are always able to know exactly how we should act in a certain situation because we have either a theoretical foundation or a command upon which to base all of our decisions.
In this case, as Kant pointed out with his categorical imperative, I know that at all times and in all situations I should never make an exception of myself. I should never act in a way that I cannot at the same time will to be universalized. For example, if I cannot will that all people download illegal music from the internet, I should refrain from doing the same myself.
However, this theory also has its disadvantages. On the one hand, it is difficult to get all people to agree on the same law or the same commands. If people do not recognize the same authority, their deontological ethic will differ substantially. On the other hand, it is possible to universalize any command if one would like, such as “don’t eat ice-cream on Sundays”.
There is nothing wrong with this principle, but as an ethical command it is rather nonsensical. As such, deontology needs some other criteria for deciding which duties should be universalized than the theory itself allows.
Kant, Immanuel (1948). Groundwork of the Metaphysics of Morals. (H. J. Paton, Trans.). London: Hutchinson. (Original work published 1785, and published in a collection in 1903; page references to this edition).
Kant, Immanuel (1836). The Metaphysics of Ethics. (John William Semple, Trans.). Edinburgh: Thomas Clark. (Original work published 1785).