Plato

• Platonic ethics has been a constant theme of ethical thinking for well over 2400 years. The role of the theory is to place reason over both the passionate and motivational parts of the soul. It places a brake on the ego so it can enjoy the realm of truth. Truth is intellectual and never changing, and therefore, it is only the reason that can reach and understand it. The person's soul, if properly arranged, brings about behavior that is in union with Truth and Good.
  
  

Augustine

• Augustinian ethics is about ultimate union with God. It is similar to Platonic ethics in that it holds that the good that people seek can never change, never go away and satisfy the whole man, not just the soul. Hunger and thirst are necessary correlates to bodily satisfaction, and to slake one's thirst is just to see another thirst coming right behind it. It is never satisfied. To base one's life around such pleasures is therefore irrational. This is not sufficient. Human beings want goods that never go away and contain the greatest pleasure. This can only be found in God.
  
  

Bentham

• The utilitarian school of ethics holds that good action brings more pleasure into the world than there was before. All actions are considered bad if they decrease the amount of pleasure in the world. This view, developed by Jeremy Bentham, holds that the only usable ethical formula is that people are repelled by what is evil and attracted to what is good. The repulsion or attraction is what makes such things good or bad. Its role therefore, is to maximize what most people think is good and reduce what most people think is bad.
  
  

Kant

• The very opposite of Bentham can be found in Immanuel Kant. Duty, not pleasure, is the real role and goal of ethical life. The role of Kant's ethics is to keep the will free. If it is free, then it has no personal, selfish interest it is trying to manifest in the world. Therefore, the will is universal and covers all willing. This universal maxim then states that one can only will an action that everyone can will. Cheating is bad because if everyone were to will it, trust in society would fall apart, leading to total chaos. If it can be willed by all, it is free, since there is no personal interest motivating the will. Hence, the universal maxim is what should be the grounding of ethical life.