Teleological moral systems are characterized primarily by a focus on the consequences which any action might have (for that reason, they are often referred to as consequentalist moral systems, and both terms are used here). Thus, in order to make correct moral choices, we have to have some understanding of what will result from our choices. When we make choices which result in the correct consequences, then we are acting morally; when we make choices which result in the incorrect consequences, then we are acting immorally.
Deontological moral systems are characterized primarily by a focus upon adherence to independent moral rules or duties. Thus, in order to make the correct moral choices, we simply have to understand what our moral duties are and what correct rules exist which regulate those duties. When we follow our duty, we are behaving morally. When we fail to follow our duty, we are behaving immorally. In natural law Aristotle stated that there is a universal natural law that our whole world should follow, and this law is determined by a supernatural power.
Later in the 13th century Thomas Aquinas developed Aristotle’s theory and said this supernatural power was God. This theory is an absolutist theory, and most absolutist theories are de-ontologically ethical, however some are not. Situation ethics was developed in the 1960’s by Joseph Fletcher as a reaction to Christian legalism and antinomianism, this is the belief that there are no fixed moral principled but morality is the result of spontaneous acts. There are four rules to situation ethics and six fundamental principles which, according to Fletcher, is what the whole ethical theory depends on.
Teleological ethical theories are consequential in nature because they assert that the morally correct action is one that produces the greatest balance of good over bad consequences compared with alternative actions. Deontological ethical theories are non-consequential and regard the rightness or wrongness of an action as intrinsic to the action itself. There, the consequences are morally irrelevant. Utilitarianism is the best-known teleological theory. Deontological theories include Kant’s categorical imperative, human rights theories, and divine command theories.