These are typically based on the human desire for equality as well as the desire to do good ("What is Natural Law?"). Furthermore, natural rights evolve legally from natural laws often. They also often see an intertwining of religious beliefs, although they can also be expressed as more an intertwining of moral beliefs that are then supported by religion. The primary weakness of natural law theory is that it is sometimes difficult to determine if a belief is truly universal, or simply cultural. Virtue Ethics:

Virtue ethics determines whether an action is right or wrong by the virtue of the action.

Virtue ethics is currently one of three major approaches in normative ethics. It may, initially, be identified as the one that emphasizes the virtues, or moral character, in contrast to the approach which emphasizes duties or rules (deontology) or that which emphasizes the consequences of actions (consequentialism). Suppose it is obvious that someone in need should be helped. A utilitarian will point to the fact that the consequences of doing so will maximise well-being, a deontologist to the fact that, in doing so the agent will be acting in accordance with a moral rule such as "Do unto others as you would be done by" and a virtue ethicist to the fact that helping the person would

be charitable or benevolent ("Virtue Ethics").

One...

It also relies upon the character of the individual to do what is virtuous. Although it may be legal to take an action, virtue ethics theorizes that a virtuous person will still take the more ethical action, if given the decision. It also accounts for the social influence on what is accepted as morally correct behaviors. However, there is a significant weakness to virtue ethics. This weakness is that what individuals perceive to be virtuous is not the same across cultures or even individuals. As an example, Al Qaeda see it as virtuous to hijack a plane and commit an act of terrorism. Most Americans would say that this action is the antithesis of virtue.
Works Cited

"Kant's Moral Philosophy." Stanford Encyclopedia of Philosophy. N.p., 23 Feb. 2004. Web. 9 Feb. 2011. .

MacKinnon, Barbara. Ethics: theory and contemporary issues. Belmont, Calif.: Wadsworth Pub. Co., 1995. Print.

"Virtue Ethics." Stanford Encyclopedia of Philosophy. N.p., 18 July 2007. Web. 9 Feb. 2011. .

"What is Ethical Relativism?" Philosophy - AllAboutPhilosophy.org. N.p., 2011. Web. 9 Feb. 2011. .

"What is Natural Law Theory?." wiseGEEK: . N.p., 1 Jan. 2011. Web. 9 Feb. 2011. .