The idea of contract theory germinated as early as the ancient Greek school of wise men, and then Epicurus, the ancient Greek philosopher, clearly expounded it. Regard the state and law as the products of mutual agreement. 15 ~ 16 th century, some aristocratic thinkers who opposed tyrants systematically discussed the idea of contract theory and used it as the basis for resisting unfair rule. The most popular period of contract theory was17 ~18th century. The main representatives are J. Arctius, H. Grotius and B. B. de Spinoza in the Netherlands, T. Hobbes and J. Locke in Britain, S.von Pufendorf in Germany, J.-J. Rousseau in France, etc. The contract theory in this period is generally based on the theory of natural law, which holds that human beings originally lived in a natural state without state and law, were dominated by natural law and enjoyed natural rights. However, due to various inconveniences, in order to better realize natural rights, people unite, conclude contracts and establish a country. Thinkers have different understandings of the form and essence of contracts and come to different political conclusions. These different conclusions reflected the political needs of the bourgeoisie under different historical conditions and played a progressive role in the anti-feudal struggle. /kloc-after the 0/9th century, the contract theory was criticized by various kinds and gradually declined. A new contract theory emerged in the 20th century, mainly represented by J.B. Rawls of the United States. The "contract" or "original agreement" he said was not made for participating in a special society or creating a special form of governance. The purpose of contract is only to establish a basic moral principle to guide the design of the basic social structure, that is, the principle of justice. It is believed that this principle must include two parts, one is the principle of equality and freedom, and the other is the combination of the principle of social fairness and equality and the principle of difference.

Survival is a competition, because before the competition begins, no one can guarantee that he will be the final winner of violent competition, and the loser of violent competition pays too much, usually even his life. Therefore, civilized society has created such a rule: the range of means that can be selected in competition is limited to the range that can ensure that the most basic interests of losers will not be harmed, and the first thing is to eliminate violent means of competition. This should be the earliest "limited responsibility system" and what westerners call "fair competition".

People who are willing to accept the behavioral constraints stipulated by the rulers in the contract, that is, the legal constraints, become citizens of civilized society. Rulers or agents will protect their interests according to the law, or punish citizens who violate the law and hurt the interests of other civilized citizens who have signed contracts with rulers.