In its simplest form Utilitarianism is a theory that says that you should decide what you do in order to provide the most happiness and the least pain in a situation.
It is therefore Hedonistic - it is centred around pleasure.
As you look at all the different possible outcomes of a situation to see where pleasure and pain will be balanced the best, it is consequentialist or teleological.
As the outcome of a different ethical question will be different each time, it is relativist.
Jeremy Bentham (1748-1832) stated that naturally we are ruled by two key things - pleasure and pain - two basic instincts.
'Nature has placed mankind under the governance of two sovereign masters, pain and pleasure. It is for them alone to point out what we ought to do as well as to determine what we shall do.' (Bentham, Introduction to the Principles of Moral Legislation, 1789)
Bentham said that we need to look at the possible things we might do and the various outcomes and calculate how much pleasure and pain they might create, finally choosing the one that best maximises pleasure and minimises pain. His approach is therefore quantitative.
He said we need to consider seven different factors, his Hedonic Calculus or the Felicific Calculus.
1. Intensity (how great the pleasures/pains will be)
2. Duration (how long the pleasures/pains will last)
3. Certainty (how likely certain outcomes are)
4. Propinquity (how near to you the pleasures/pains will be - i.e. how much they will affect you personally)
5. Fecundity (how likely the pleasures/pains will be followed by similar pleasures/pains)
6. Purity (how likely the pleasures/pains will be followed by the opposite types of pleasures/pains)
7. Extent (how many people will be affected by it)
Advantages of Bentham's Utilitarianism
It is reasonable to link morality with the pursuit of happiness and the avoidance of pain and misery.
It is also natural to consider the consequences of our actions when deciding on what to do
Criticisms of benthams utilitarianism
You cannot predict the future so the calculations cannot always be accurate.
Pain can be good and pleasure can be bad, therefore utilitarianism can be contradicted.
There are certain things that are intrinsically good or bad, so there is no reason to do calculations each time.
Should animals be considered in the equation? The environment?
Some would say that we have a particular obligation to our family.
The majority may sometimes be corrupt (for example two prison guards who got pleasure out of torturing a prisoner might be allowed to do it under Bentham's Utilitarianism).
Act vs Rule Utilitarianism
Bentham is sometimes referred to as an Act Utilitarian because in his view each time you need to consider each act individually.
Mill relies on rules more, and is sometimes known as a Rule Utilitarian. However some scholars are uncomfortable with this as Mill advocated following general rules that could be broken when necessary. He is therefore sometimes known as a Weak Rule Utilitarian.
By contrast Strong Rule Utilitarianism would say that utilitarian principles should establish rules that should then never be broken - which might become an absolutist theory