Utilitarianism is a way of looking at ethics, it focuses on trying to ensure the maximum happiness in many different ways. There are many different forms of utilitarianism, the four I will discuss are act, rule, naive and preference utilitarianism.
Rule utilitarianism tries to give the greatest overall benefit to society, the best rule/law of conduct is found and everyone is found an a rule utilitarian will follow it. However, this can cause problems if you use this rule in a place where it is not generally followed as problems will be caused if you differ from the general population. Another difficulty is that all the best rules would be very complicated and this would make them hard to follow and many people would not bother to follow them at all.
Examples of rule utilitarianism: A man needs a lot of money to get a lifesaving operation on his heart, he doesn't have the money and contemplates robbing a bank for it.
Because he follows rule utilitarianism he decides to let himself die because robbing a bank is against the rules that he believe are for the benefit of society. Another example: A man from the USA comes to Australia to live, one of the rules he believes is for the greater benefit of society s driving on the right side of the road. He is forced to go against his rule utilitarianism because of the fear of a car crash.
Preference utilitarianism tries to satisfy peoples' preferences. The best action is the one which satisfies the highest amount of peoples' preferences. These preferences must only count for preferences about oneself or people might have preferences that cancel out other peoples preferences (for example: A person wishing to be rich and a person wishing for everyone to be poor),