The political philosophy that is shared by developed countries in the early 21st century is individualistic liberalism, which seeks to expand the liberties of individuals to the greatest degree possible. Liberalism discusses appropriate ways of stably maintaining and developing representative democracy, which is a political system intended to realize liberties, and concepts that provides its foundation.
Modern liberalism includes various schools of philosophy, among which there have been a variety of arguments. A Theory of Justice (Rawls, 2010), written in 1971 by John Rawls, an American political philosopher, formed the foundation of, and determined the paradigm for, those arguments. In A Theory of Justice, Rawls criticized utilitarianism and theorized about a form of liberal thought that places more focus on equality. Here, I will first provide an overview of Rawls' thought based on A Theory of Justice and Justice as Fairness: A Restatement (2001), which was compiled as an edited collection of lecture notes from his last years, and clarify the challenges faced by Rawls' version of liberal philosophy.
Rawls considers it the ultimate goal of political philosophy to stably maintain society as a political community over a long term. Encouraging people with various desires and passions and different goals to think of society as a whole is one of the goals of the political philosophy advocated by Rawls at the beginning of Justice as Fairness: A Restatement. More specifically, Rawls argues that the role of political philosophy is to encourage people to think of their various political and societal systems as a whole and to consider the basic ends and objectives of the systems to be those of a society with its own history—a nation—rather than those of individuals, families or members of associations, by showing which of all possible ends are based on justice and reason and how those ends can be made compatible with each other. In American society, which Rawls had in mind when he presented these ideas, there are clashes of various religious and cultural opinions among the people, which, fundamentally, cannot be reconciled. The role of political philosophy is to encourage the people to develop a sense of acceptance regarding the presence of such clashes of irreconcilable opinions, to mitigate any xenophobia against other people with different opinions, and to have a positive view of their society. In other words, political philosophy should encourage diverse groups of people to become reconciled with society and to live a positive life, and it should present what the "just form" of political and economic systems that would realize this end is like.
Given the goal of political philosophy, which is to encourage reconciliation and harmony between people with diverse backgrounds and opinions, the political philosophy as conceived by Rawls must be an idea that can be shared by people with different religions, cultures and philosophies. In other words, from Rawls' point of view, the political philosophy must be a theory that can serve as the common denominator ("overlapping consensus," to use Rawls' own phrase) of various thoughts and opinions. The Rawlsian political philosophy can be summarized as the two principles of justice, which were discussed in A Theory of Justice. The two principles of justice, which define "the just form" of human society, are as follows:
The first principle maintains that each individual has a claim to basic liberties (liberties of thought and belief, speech, and choice of occupation) as long as the claim is compatible with other people's claims to those liberties.
The second principle sets the conditions for tolerating the presence of social and economic inequalities. The conditions are "fair equality of opportunity" and the "difference principle." The principle of "fair equality of opportunity" requires that all people be given equal opportunity to benefit from a socially or economically beneficial position. The presence of inequalities may be tolerated only if fair equality of opportunity is ensured. The "difference principle" requires that social and economic inequalities be arranged so that they are to the greatest benefit of the least-advantaged members of society (who are referred to here as the "most vulnerable"). In other words, the presence of social and economic inequalities may be tolerated as being in accordance with justice only on condition that the existence of those inequalities bring greater benefits to the most vulnerable than does their absence.
Rawls deduced the difference principle within his famous "veil of ignorance" theory. Rawls argues that people agree on the difference principle as a social contract in the "original position," and elaborates on the argument as follows. In the original position, people are ignorant of their own societal attributes (e.g., their intellectual and physical capacities and the social class and economic status of the families into which they were born). Rawls called this state a veil of ignorance. People in the original position, who are wrapped in a veil of ignorance, explore a consensus on the principles of justice (the just form of society) while sharing common knowledge regarding human society. This sounds more like a policy decision model under representative democracy than a hypothetical origin of a history.
Under Rawls' theory, people are supposed to be rational and self-seeking, but when wrapped in a veil of ignorance in the original position, they worry more over what benefits they would receive if they were to become socially most vulnerable. As a result, they agree on the difference principle, which requires that social and economic inequalities be arranged so that they are to the greatest benefit of the most vulnerable.
In this case, Rawls simply assumes that people wrapped in a veil of ignorance would worry most about the benefits that they would receive if they were to become a member of the most vulnerable class and provides no detailed explanation as to why it should be so. One plausible explanation (although Rawls himself is said to have disagreed with it) is one offered from the perspective of economics based on the theory of Knightian uncertainty.
In economics, uncertain incidents whose probability distributions are known are referred to as "risks," but in the real world, there are deep uncertainties whose probability distributions are unknown. The "deep" category of uncertainty whose probability distribution is unknown is called Knightian uncertainty, after Frank K. Knight, an economist who emphasized the difference between the two categories of uncertainty (Knight ).
Let us take the case of people who want to avoid Knightian uncertainty but actually face that uncertainty. It has been mathematically proven that under Knightian uncertainty, if people facing uncertainty are to benefit themselves maximally in a self-seeking, rational manner, they choose the option that would maximize the benefits to be received in a worst-case scenario.
We presume that what is faced by people wrapped in a veil of ignorance in the original position is deep uncertainty in which the probability distribution is unknown (Knightian uncertainty). Regular business cycles that occur where political and market systems are established are types of random events whose probability distributions are known. That is because people in the original position, who have yet to decide what kind of social system to develop, may be considered as facing a Knightian uncertainty whose probability distribution is unknown.
In this case, as long as people in the original position make decisions in a rational, self-seeking manner, they agree to the arrangement of social inequalities that would be to their greatest benefit if they were to become socially most vulnerable. This principle strictly applies under the assumption that people tend to make efforts to avoid Knightian uncertainty. In other words, the difference principle may be described as the principle for tolerating the presence of inequalities agreed upon by rational people as a result of self-seeking maximization of their own benefits in the event of a Knightian uncertainty.