It is common for us to determine our moral responsibility by weighing the consequences of our actions. According to consequentialist normative theories, correct moral conduct is determined solely by a cost-benefit analysis of an action's consequences:

Consequentialism: "An action is morally right if the consequences of that action are more favorable than unfavorable."

Consequentialist normative principles require that we first tally both the good and bad consequences of an action. Second, we then determine whether the total good consequences outweigh the total bad consequences. If the good consequences are greater, then the action is morally proper. If the bad consequences are greater, then the action is morally improper. Consequentialist theories are also called teleological theories, from the Greek word telos, or end, since the end result of the action is the sole determining factor of its morality.

Consequentialist theories first became popular in the 18th century by philosophers who wanted a quick way to morally assess an action by appealing to experience, rather than by appealing to gut intuitions or long lists of questionable duties. In fact, the most attractive feature of consequentialism is that it appeals to publicly observable consequences of an action. Most versions of consequentialism are more precisely formulated than the general principle above. In particular, competing consequentialist theories specify which consequences for affected groups of people are relevant. Three subdivisions of consequentialism emerge:

Ethical Egoism: "an action is morally right if the consequences of that action are more favorable than unfavorable only to the agent performing the action."

Ethical Altruism: "an action is morally right if the consequences of that action are more favorable than unfavorable to everyone except the agent."

Utilitarianism: "an action is morally right if the consequences of that action are more favorable than unfavorable to everyone."

All three of these theories focus on the consequences of actions for different groups of people. But, like all normative theories, the above three theories are rivals of each other. They also yield different conclusions. Consider the following example. [A woman was traveling through a developing country when she witnessed a car in front of her run off the road and roll over several times. She asked the hired driver to pull over to assist but, to her surprise, the driver accelerated nervously past the scene. A few miles down the road the driver explained that in his country if someone assists an accident victim, then the police often hold the assisting person responsible for the accident itself. If the victim dies, then the assisting person could be held responsible for the death. The driver continued explaining that road accident victims are therefore usually left unattended and often die from exposure to the country's harsh desert conditions.] On the principle of ethical egoism, the woman in this illustration would only be concerned with the consequences of her attempted assistance as she would be affected. Clearly, the decision to drive on would be the morally proper choice. On the principle of ethical altruism, she would be concerned only with the consequences of her action as others are affected, particularly the accident victim. Tallying only those consequences reveals that assisting the victim would be the morally correct choice, irrespective of the negative consequences that result for her. On the principle of utilitarianism, she must consider the consequences for both herself and the victim. The outcome here is less clear, and the woman would need to precisely calculate the overall benefit versus disbenefit of her action.