What is the difference between deontological and teleological ethics systems?

One factor we can use to better understand how to apply an ethical theory is to determine whether it is deontological or teleological. Deontological ethics systems rely on our sense of duty to act according to what is right. Therefore, they are very much focussed on whether an action is morally right in and of itself, rather than looking to the consequences, intentions or motives of an action. We might say that these rules are therefore 'absolute'- they hold complete authority and do not change to fit different situations, but rather should be applied all the time. An example of a deontological theory includes Aquinas' Natural Moral Law, since it proposes a set of key 'primary precepts' and appeals to our duty to follow these , regardless of the situation we may be in; for example the rule that we must always act to 'preserve life' - i.e. to not kill.A teleological theory, on the other hand, looks to the consequences or 'end' of an action to deterine whether it is morally right. This comes from the Greek word 'telos' meaning 'ultimate aim'. A teleological theory can therefore be applied situationally and contextually - we must consider whether an action in a given situation will produce a desired outcome. In Bentham's theory of Utilitarianism, for example, all actions that lead to 'pleasure' or 'utility' are morally right. In this case, we cannot say 'killing is always wrong', but should consider cases separately for their outcomes: for example in the case of death penalty for a proven serial killer, this may be seen as morally justified as it reduces overall pain.