1. Introduction

In his book A Theory of Justice, Rawls demonstrates the thought of "fair justice", criticizes the utilitarian view of justice which has long occupied the mainstream in the West, and draws a conclusion different from that of welfare capitalism. The criticism of utilitarianism is the breakthrough point of Rawls's theory. From his perspective, both classical utilitarianism, which maximizes the net balance of satisfaction, and average utilitarianism and limited utilitarianism, which are more complex, have the same fatal drawbacks. On the one hand, utilitarianism ignores the principle of equality and lacks a reasonable response to the problem of distribution of wealth. Although utilitarianism can increase the total amount of resources, it cannot guarantee the equal distribution of benefits and costs, which will eventually lead to the widening gap between the rich and the poor [1]. Secondly, utilitarianism incorporates the separative individual interest system into the social interest system, and requires that the individual interest be subordinated to the goal of maximizing social utility. To this end, the exploitation and inequality suffered by minorities are considered "reasonable sacrifices", which means that the fundamental rights of individuals can’t always properly and soundly upheld. Thirdly, the shortcomings of utilitarianism in moral principle cause its legitimacy dilemma. The teleological tendency of utilitarianism determines that it only considers the result of utilitarian calculation, but does not pay attention to the moral legitimacy of the source of utility. This makes it difficult for utilitarianism to gain the support of a sense of justice. By comparing with utilitarianism，Rawls overturns the maximization principle of social utility held by utilitarianism by emphasizing justice and equality, and demonstrates the advantages of "justice as fairness".

The difference between utilitarianism and "fair justice" is reflected in the opposition between teleology and deontology in ethics, that is, which comes first between "right" and "good". Rawls's "two priority principles" on the principle of justice essentially reflect the priority of "right" over "good". In contrast, the utilitarians represented by Hume, Mill and Helvétius put the pursuit of "good" in the first place, and then affirmed the principle of supremacy of freedom and market economy. Rawls's equal liberalism, which promotes the pursuit of justice in the social contract theory，puts forward the principle of justice with the dual value of freedom and equality, and forms the left-wing ideology that reconciling individual rights and free market.

The object of Rawls's principle of justice is "the basic structure of society -that is, the principal system by which the basic rights and duties of citizens are distributed, and the benefits and burdens arising from social cooperation are divided." [2] He upholds and transforms the tradition of Contractarianism and uses rigorous political philosophical analysis to demonstrate two principles of justice that people jointly choose through public reason. Rawls's theoretical construction is based on human rationality, replacing multiple moral judgments with reasonable and prudent choices, and taking rational and just democratic government and political order as the natural pursuit. The theory of justice demonstrates the authority of human reason, and reason has become a key to interpret Rawls's thought of justice.

2. Rationality and Utilitarianism

2.1. The shared rational foundation

Both the utilitarian calculation of interests and the public reasoning required by the theory of justice are based on the common basis of human rationality. Reason gives people the ability to judge, choose and decide, and provides the possibility for cooperation between people. In Rawls's theory, people in the original state are rational people who are purely selfish, just like what utilitarianism recognizes. People are indifferent to each other and each pursues the "basic good" of society [3]. Rational ability is the basis of justice ability, which enables people to establish justice belief, choose justice standards, act according to justice standards, and expect others' behavior to meet the requirements of justice, which is the premise of forming a consistent view of justice in society. In addition, there is an essential difference between rational self-interest and egoism. By "rational citizens," Rawls means "free and equal citizens who can cooperate with others under all acceptable conditions." [4]. Starting from the basis of shared rationality, utilitarianism and a theory of justice diverge.

Taking the hypothesis of rational man as the starting point, the contracting parties in the original state jointly pursue "basic good" and make a public choice on the principle of justice. On the basis of the social contract theory, Rawls designed the "Veil of ignorance" in order to construct a fair procedure to determine the principle of justice. Under the veil of ignorance, the hypothetical contracting party only has knowledge of basic facts and laws, excluding its own class, status, qualifications, existing ideas, social conditions and other differentiated information. Rather than relying on people's moral intuition, it deduces moral rules by combining people's concern for their own interests with their ignorance of their own interests, thus constructing a moral law that almost everyone can agree on [5].

Rawls' justification for the veil of ignorance have distinct layers and structures [6]. The existence of the veil of ignorance, on the one hand, limits people's selfish pursuit, guarantees the fairness and consistency of the universally recognized principle of justice, on the other hand, provides the basis for the public reasoning of justice, so that the consensus view of justice can be reached. First of all, under the assumption of the veil of ignorance, individuals cannot care about their own special interests in the choice of the principle of justice due to insufficient information, so they can limit people's selfish tendency and make it possible for people to unanimously choose a certain concept of justice. Secondly, the veil of ignorance removes the influence of natural and social contingencies, covers up people's various notions of good, and provides conditions for the realization of public reason. Rawls' public reason goes beyond the self-interest dimension of utilitarian rationality, and connects rationality with "legitimacy", human moral sense and sense of justice.

Utilitarianism believes that human reason tends to the goal of "good", and takes "good", happiness, and "good" as the only criteria for rational action. For Rawls and his followers, righteousness is more important than goodness. He relates rationality with righteousness, and citizens make collective reasoning based on the public concept of justice, excluding the private and small coalition rationality from the public rationality, and forming the universal principle of justice through overlapping consensus.

2.2. Rawls' criticism of utilitarianism

Rawls systematically reveals the inherent defects of utilitarianism from the aspects of basic theory, argumentation method and philosophical view. He attributed these defects to its teleological philosophical position. Utilitarianism holds that "good" is the satisfaction of rational desire and is the ultimate goal independent of "right". However, its treatment of the good is too simple. The social utility-maximization goal of utilitarianism includes the individual desire system into the overall social desire system, ignoring the difference between individual independence and individual rational desire, thus eliminating individual liberty and making it difficult to confirm individual rights. As Will Ginricka said, utilitarianism "is not about respecting people... Their aim is to respect interests - with particular people becoming either useful or useless instruments "[7]. The doctrine never sees the individual as a value subject independent of society, with its own will and interests, but merely as a tool to achieve social utilitarian goals.

Rawls insists on the principle of priority of liberty and rights in his theory of justice, which regards human liberty and rights as irreducible basic values. on the contrary, Utilitarian is instrumentalist in its attitude towards rights. Even though its theory contains the assertion of individual rights, it aims to realize utility-maximizing in the final analysis. It adopts the holistic concept of society, regards society as an organism, and tries to integrate individual values into the overall "good" goal. This attitude ignores the separability of individuals from society, and lays a hidden danger for realizing social goals at the expense of minority interests.

From the perspective of methodology, Rawls regards the social contract as a means to discover justice. The public choice of rational contracting parties is the source of the legitimacy of the principle of justice. The reasoning process of utilitarianism, which is contrary to the social contract theory, assumes the perspective of an "impartial sympathetic observer" [4], once again extends the principle of individual choice to the social level. Utilitarianism holds that all interests can be governed by a dominant purpose, so as to achieve the highest "good". But in reality, people's goals are independent and different, and may conflict with each other. Individuals can make choices that serve their own best interests by comparing options and sacrificing certain options appropriately. Moreover in the social level, it may be unjustified for society to rank people's goals in terms of the greatest overall good, because there is no guarantee of compensation for those who sacrifice. The "impartial compassionate observer" is not a self-interested, limitedly rational individual, but an altruistic, perfectly rational transcendent. Altruists only consider the interests of others, and there is no conflict of interests between each other, so there is no need to determine any moral code to regulate social behavior. In this position, people cannot formulate any effective principles of justice. The method of "impartial sympathetic observer" is not only impossible in reality, but also difficult to produce effective reasoning results in theory.

3. Two principles of justice

3.1. The principle of maximum equal liberty

Based on the original state and the veil of ignorance, Rawls' argument points to the just principle of social public choice. The first question he faced is, how are the principles of justice chosen. Rawls uses game theory to make inferences. On the basis of the original state and the veil of ignorance, Rawls postulates three possible circumstances and possible choices for the principle of justice, and assigns objective monetary value to them. In this game, according to the maxmin-criterion, people will choose two principles of justice that they agree with.

In the original state, those who adopt the maxmin-criterion will eventually choose and adhere to the two principles of justice recognized by Rawls. First: Each person is to have an equal right to the most extensive total system of equal basic liberties compatible with a similar system of liberty for all; Secondly, Social and economic inequalities are to be arranged so that they are both: (a) to the greatest benefit of the least advantaged, consistent with the just savings principle, and (b) attached to offices and positions open to all under conditions of fair equality of opportunity. After determining the principles of justice, Rawls gives a "lexicographic sequence" to solve the possible conflicts between the principles of justice, and prioritizes the principles of justice. Rawls puts liberty in the first place. He believes that justice is to establish the most basic liberty system in society, and the construction of a social freedom system first needs to establish the priority of freedom [8].

Rawls emphasized, "Only when the claim to liberty is satisfied, can the other principles come into play." [9]For rational people, self-esteem is the most important "basic good", and the basic liberty of equality is the basic need for citizens to maintain self-esteem. "The effective protection of equal freedom is increasingly of Paramount importance in supporting self-esteem" [4]. Fundamental freedom is a necessary condition for the exercise of reason. As Rawls puts it, "Free men see themselves as those who can amend and change their ultimate ends, and as those who give the utmost priority to the preservation of their liberty in these matters." [4]. This ability to "modify and change" one's own ends is precisely the exercise of rational superlative interests. Even the smallest restrictions on fundamental freedoms limit the autonomy of reasonable people and may constitute a threat to this higher interest.

As the first principle of justice, Rawls' interpretation of liberty takes into account various relative values of liberty, and integrates the concepts of positive liberty and negative liberty. He believed that political liberty had the same value as liberty of conscience, individual and civil liberty, and that it is inadvisable to sacrifice one at the expense of the other. But liberty, if not restricted, can also come into conflict with one another. And the primacy of liberty means that it can only be restricted for its own sake. In order to solve this problem, Rawls regarded the basic liberties as a whole system, the values of various liberties are measured against each other, the value of one liberty depends on the provisions of other ones, and the best arrangement of several liberties depends on the general constraints to which they are subject.

3.2. The principle of fair equality of opportunity and difference principle

The second principle of justice proposed by Rawls is the combination of "the principle of fair opportunity of equality" and "difference principle ". It first require that positions and status in society be open to all under conditions of fair and equal opportunity. Difference principle states that, consistent with the principle of the preservation of justice, social and economic inequalities should be arranged in the best interests of the fewest beneficiaries. The second principle of justice further embodies the egalitarian advocation in Rawls's theory, which is committed to reducing the influence of arbitrary factors on people's differences, and promoting and realizing the substantial social equity in the distribution of opportunities and benefits. Among them, difference principle is one of the most important theoretical contributions of the theory of justice, but also his most controversial point of view.

Rawls' emphasis on the interests of "least beneficiaries" shows the distinct egalitarian tendency in his theory of justice. First, Rawls advocates equal distribution; But Rawls also pointed out that an unequal distribution is just if it serves the interests of everyone, including the least beneficiaries. However, if the degree of inequality is too large, or constantly accumulated, it will result in substantial inequality by failing to guarantee equal social conditions for individuals. Therefore, Rawls further defines the difference principle and restricts the inequality allowed by the difference principle. He proposed "lexical order". In a society with different classes, firstly it is necessary to maximize the welfare of the least beneficiaries. Secondly, to maximize the welfare of the next least advantaged , and reason by analogy. Finally, to maximize the welfare of the best advantaged for the sake of the equal welfare of all preceding classes [10].

The reason why Rawls put forward difference principle is to overcome the influence of contingency factors in social life on distribution, eliminate the obstacles caused by it and adverse conditions of luck to people's pursuit of freedom and equality of opportunity, so that the demand for equality is not only in form, but has the guarantee of substance and results. Difference principle emphasizes the interests of the "least beneficiaries" and requires that the resources should be tilted to the least beneficiaries in the process of redistribution, which is a clear embodiment of Rawls' egalitarian thought. Egalitarianism constitutes the most important moral basis for the principle of difference. As a liberal, Rawls takes into account the situation of the disadvantaged in society while emphasizing the priority of liberty and equality of opportunity, and tries to implement the equality of rights and opportunities with the distribution that benefits the least beneficiaries.

Difference principle mainly reflects Rawls' ethical concern for the disadvantaged groups and the underclass. His explanation and application of difference principle also makes his theory significantly different from other theories of justice and has unique theoretical value and contribution. The multi-perspective interpretation of difference principle has also become the key reason why Rawls's theory of justice is quite controversial.

4. Conclusion

A Theory of Justice responds to people's pursuit of rational and just political order in the context of political conflicts in the 20th century. After that, Rawls continued his in-depth exploration of the issue of justice on the basis of his theory of justice. In Justice as Fairness：A Restatement and Lectures on the History of Political Philosophy, Rawls took "Marx's critique of liberalism" as the lead and came to the conclusion that "justice as fairness" is different from welfare capitalism [11], continuously reflecting and criticizing the utilitarian value system in Western economic, political, and social systems. Rawls inherited and improved the classical contract theory, and he restored the original position of the social contract theory in political philosophy. Rawls replaced the abstract state of nature with the "original state" under the veil of ignorance. Starting from the reality of social inequality, Rawls restated contract consent with the choice of justice principle rather than the transfer of rights, making a new contribution to the development of the social contract theory [12].

Rawls's theory of justice is the most outstanding theoretical achievement of political philosophy in the 20th century. At the same time, Rawls's theory of justice has also been questioned and challenged from both left and right wings. Liberals believe that the principle of justice promotes fairness through redistribution, which leads to excessive intervention by the state in individual life and an infringement on people's rights and liberty. On the other hand, communitarianism criticizes the individualistic tendencies displayed by "equal liberty" and argues that equal liberalism still does not go far enough. Rawls appreciates the systemic and constructive features of utilitarianism, and his theory of justice also showed a tendency to try to achieve comprehensiveness, synthesis and balance. Michael Sandel believes that there is a tension between certain aspects of Rawls’s theory and his criticisms of utilitarianism. For example, while criticizing utilitarianism for ignoring the particularity of individuals, the difference principle of justice theory regards talent as the common asset of society. This view also infringes the particularity of human beings and has the same problems as Rawls' criticism of utilitarianism [13].Rawls's political philosophy has attracted much attention and been widely debated. However, there is no doubt that he is one of the greatest political philosophers since the 20th century. He promoted the shift of Western philosophy to substantive issues.