This is an outline and summary of three of the most prominent ethical theories in the history of philosophy. (Note that all three of these represent different ethical absolutist/universalist theories. A view known as ethical relativism follows these.) Please take this as a sketch that invites you to investigate these ethical theories further. After each brief sketch, I will provide some web links that will be helpful to read.
Virtue Ethics (especially Aristotle)
From Wikipedia (http://en.wikipedia.org/wiki/Virtue_ethics):
“Virtue ethics is a branch of moral philosophy that emphasizes character, rather than rules or consequences, as the key element of ethical thinking. In the West virtue ethics was the prevailing approach to ethical thinking in the ancient and medieval periods. The tradition suffered an eclipse during the early modern period, as Aristotelianism fell out of favour in the West. Virtue ethics returned to prominence in Western philosophical thought in the twentieth century, and is today one of the three dominant approaches to normative ethics (the other two being deontology and consequentialism).” “A system of virtue ethics, having offered an account of the good life, then identifies those habits and behaviours that will allow a person to achieve that good life: these habits and behaviours are the virtues (arête). In the course of one's activities one will have opportunity to practice these virtues. Sometimes these virtues will be, or will seem to be, in conflict with one another: a common dilemma is the apparent conflict between honesty and compassion, when telling a friend the truth (about his appearance, say) would hurt that friend's feelings. In such cases the agent must exercise her practical wisdom (phronesis) to resolve the conflict. Ultimately, a lifetime of practicing these virtues will allow the agent to flourish and live the good life (eudaimonia). In fact, in most accounts, practicing the virtues partially constitutes eudaimonia rather than being merely a means to that end.” “Eudaimonia is a state variously translated as "happiness" or "human flourishing". The latter translation is more accurate; eudaimonia is not a subjective, but an objective, state. It characterizes the well-lived life, irrespective of the emotional state of the person experiencing it. According to Aristotle, the most prominent exponent of eudaimonia in the Western philosophical tradition, eudaimonia is the proper goal of human life. It consists of exercising the characteristic human quality-- reason-- as the soul's most proper and nourishing activity. Aristotle, like Plato before him, argued that the pursuit of eudaimonia was an activity that could only properly be exercised in the characteristic human community-- the polis or city-state. Although eudaimonia was first popularized by Aristotle, it now belongs to the tradition of virtue ethics generally. For the virtue ethicist, eudaimonia describes that state achieved by the person who lives the proper human life, an outcome which can be reached by practising the virtues. A virtue is a habit or quality that allows the bearer to succeed at his, her, or its purpose. The virtue of a knife, for example, is sharpness; among the virtues of a racehorse is speed. Thus to identify the virtues for human beings, one must have an account of what the human purpose is.”
Utilitarianism (especially John Stuart Mill)
From Wikipedia (http://en.wikipedia.org/wiki/Utilitarianism): “Utilitarianism is the ethical doctrine that the moral worth of an action is determined solely by its contribution to overall utility. It is thus a form of consequentialism, meaning that the moral worth of an action is determined by its outcome—the ends justify the means. Utility — the good to be maximized — has been defined by various...