In the study of ethics there are three types of ethical theories: intuition-based, end-based and duty-based. These three types of ethics seek to describe the rules, behavioral trends and moral codes that govern -- or ought to govern -- human behavior.
End-based ethics involves the idea that a person ought to do what produces the greatest good; the act that produces the greatest good is held to be the most moral act in a given situation. Whereas end-based ethics seek to produce the best result, duty-based ethics refers to a person's intentions; a person may do something that does not produce the greatest good, but if he intended for it to be a morally acceptable act, then it is. The intention is the important part. Intuition-based ethics describes the way in which individuals should do what feels right. A person should exercise their own sense of right and wrong without becoming overwhelmed with intentions or consequences.
Intuition based ethics stem from the Aristotelian philosophers, such as Aristotle and Plato. Aristotle felt that human beings are born with natural senses of right and wrong. He thought that humans have two types of virtues, intellectual virtues and appetites. Intellectual virtues involve the rational mind and making conscious decisions, and appetites refer to a person's desire or emotional response. Sexual desire would be an example of an appetite. Aristotle felt that the key to moral living and ethical behavior is balancing intellectual virtues with appetites; a person must find a happy medium between satiating desire and using the intellect.
End-based ethics, also called consequentialist ethics, are also often referred to colloquially as utilitarianism. End-based ethics require a person to do whatever will produce the greatest good. For example, if a doctor is sick and needs a new kidney, then you might decide to sacrifice your life in order to give the doctor your kidney so that she could become healthy and save thousands of lives. In this way, you have performed a morally acceptable action, as you have sacrificed your own life in order to save thousands of lives. Even if you sacrificed your kidney hatefully and with contempt for the doctor this action is still considered morally right since your intention does not matter. The only thing that matters is the greatest good in the end result.
In duty-based ethics, your intention is of primary concern. Those in support of duty-based ethics argue that you can never know what will actually produce the best result, so end-based ethics are not possible. As a result, what matters is your intention to do good; although each person may have a different concept of what constitutes a good action, individuals ought to do whatever they think is the right thing.