Historically speaking, Jeremy Bentham in his Introduction to the Principles of Morals and Legislation(1789) and John Stuart Mill in Utilitarianism (1863) are the founders of utilitarianism, while Francis Hutcheson (1755) and William Paley (1785) could be seen as their legitimate predecessors by pointing out that utility should be seen as an important standard of evaluation in ethical reasoning and decision-making. Bentham claims that the duration and intensity of pleasure and pain are of utmost importance and that it is even possible – according to Bentham - to measure the right action by applying a hedonistic calculus which determines the exact utility of the actions. The action with the best hedonistic outcome should be put into practice. His position is called radical quantitative hedonism. Mill instead questions the very idea of a hedonistic calculus and argues that one must distinguish between mental and bodily pleasure by giving more weight to mental pleasures. His position is called qualitative hedonism. Mill’s basic formula of utilitarianism is as follows:
The creed which accepts as the foundation of morals, Utility, or the Greatest Happiness Principle, holds that actions are right in proportion as they tend to promote happiness, wrong as they tend to produce the reverse of happiness. By happiness is intended pleasure, and the absence of pain; by unhappiness, pain and the privation of pleasure. (Mill’s Utilitarianism, chapter 2)
There is widespread agreement that there exist numerous different utilitarian theories in modern ethics; hence it would be impossible to provide an adequate depiction of all important major strands in this brief subsection. However, the following four main aspects are typical for each utilitarian theory. (1.) The consequence principle: Utilitarianism is not about actions but about the consequences of actions. This kind of theory is a form of consequentialism, which means that the moral worth of the particular action is determined by its outcome. (2.) Happiness: Utilitarianism is a teleological theory insofar as happiness (but, not in the ancient sense of the term) is the main goal that should be achieved. This particular goal can be identified with (i.) the promotion of pleasure, (ii.) the avoidance of pain or harm, (iii.) the fulfilment of desires or considered preferences, or (iv.) with meeting some objective criteria of well-being. (3.) Greatest Happiness Principle: Utilitarianism is not about mere happiness but about “the greatest happiness” attainable. Utilitarianism is a theory with one principle that judges the consequences of a given action regarding its utility, which is the general aim of actions. The moral rightness or wrongness of actions depends on the goal of achieving the greatest happiness for the greatest number of sentient beings, in short, “the greatest happiness for the greatest number”. (4.) Maximising:The collective amount of utility regarding sentient beings affected by the action should be maximized. This line of reasoning contains strong altruistic claims because, roughly speaking, one should only choose those actions which improve other sentient beings’ happiness.
Furthermore, one major methodological distinction should be mentioned briefly since it really divides all utilitarian theories in two different groups by either applying the principle of utility to actions or rules. In act utilitarianism (or direct utilitarianism) the principle of utility is applied to the particular action; in this case, one asks whether the action in question is morally right or wrong in this particular situation. In rule utilitarianism (or indirect utilitarianism), instead, the principle of utility is applied to rules only which, in turn, are applied to the particular actions and serve as guidelines for human behaviour in order to guarantee the greatest happiness for the greatest number. Here, the vital question is whether a specific rule maximises the general utility or not. From time to time, it happens that the general utility will be maximised by rule utilitarianism to a lesser degree than it would have been the case regarding act utilitarianism. For example, one should act according to the general rule which says that one should keep one’s promises which - in the long run - maximises the general utility (rule utilitarianism). However, in some cases it would be better to adhere to act utilitarianism since it maximises the general utility to a higher degree depending on the particular situation and circumstances of the case in question (act utilitarianism).