Ten world famous paradoxes have caused heated discussions among netizens. These ten paradoxes have touched upon important issues in physics, ethics, epistemology and philosophy, and are of far-reaching significance, enough to cause some important changes in theory.

“The tram problem” is one of the most well-known ideolo- gical experiments in the field of ethics. Its content is roughly as follow: A madman has tied five innocent people to tram tracks. An out of control tram approached them, and they would be crushed after a few moments. Fortunately, you can pull a lever and let the tram go to another track. But there is another problem. The madman has also tied a man on that track. Consider the above situation, should you pull the lever?

People often encounter similar problems in their lives. The principle of justice is necessary to make correct decisions. What are the fundamental principles of justice? There are two perspectives. One is the benefit as the ultimate principle, the other is dogma. We have heard many dogmas and rules, Confucian dogmas, Christian dogmas, Kant's moral principles, communist spirit, socialist core values, and so on. These principles often conflict with each other and make people at a loss. For example, Kant stated that we must not kill anyone. Everyone's humanity is a purpose and cannot be used as a means. According to this principle, it is not allowed to pull the lever, because it is to use that person as a means to save other people.

Every dogma is defined by people. None of them is priori. What is the basis for people to put forward these principles? It is the benefits of the people. Therefore, the benefits of people are the ultimate value standards. This kind of thinking is called humanism or utilitarianism.

The most important principle of humanism is to provide the greatest benefit for the most people. According to this principle, we should sacrifice one person's benefits to save multiple people. This is not like some people saying that they violate the Utilitarian principle and it is just the correct decision precisely based on utilitarian principles.

There are different relations between human benefits, so the standards of justice need concrete analysis. The relationship between people's benefits is divided into two types: one is conflict, one rises as the other fall (up-down); and the other type is non-conflict, one rise with the other rise or remain fixed (up-up). The non-conflict interests exist everywhere, and it is the unification of interests. The unification of interests is also called win-win and harmony. It is the most ideal situation. The act of justice in this relationship is both selfish and good.

Theorem: Benefit of each person is the criterion of justice when benefits of people are in the up-up relation.

When interests are united, they do not cause conflicts between people. They are what all people are willing to accept and are the basis for people's cooperation.

there are two kinds of up-down. (a) the total benefit is not able to rise or avoid to fall; (b) the total benefit is able to rise or avoid to fall.

Theorem: Both choices on benefit between the subject and others may be justice when benefits conflict and the total benefit is not able to rise or avoid to fall.

For example, there is only one champion in a sports competition. Whatever you choose it means someone has to sacrifice. At this time, whatever you choose is justice.

If the sum of benefits may increase, then one party needs to make sacrifice to achieve Paretian optimization. At this time, the choice of justice is to sacrifice the interests of someone in order to realize the greatest benefit.

Theorem: The maximization of benefit is justice when benefits conflict and the total benefit is able to rise or avoid to fall.

In many countries, efficiency is prioritized and fairness is taken into consideration. Efficiency here refers to the maximization of social benefits, not to the efficiency of a machine or a social organization.

Although it is difficult to calculate the sum of interests, people have been making such calculations and comparisons. For example, after the Vietnam War, Americans felt that national interests were overestimated and they no longer wished to sacrifice their own interests for national interests. But after “9.11”, Americans felt that national interests are very important and they were willing to pay more tax for the country's security. Each year, Congress's budget debates are mainly due to differences in the calculation of the sum of benefits.

It should be noted that the rule to maximize the sum of interests is not exactly the same as the rule that minority obeys the majority. For example, each person donates a little money to save a person's life, which is at the expense of the majority, but it is also to maximize the sum of interests, because the sum of the interests of the sacrificed majority is less than the individual's interest of that person.

When the influence of behavior on the interests of each individual is almost equal, the following inference can be derived from the above theorem:

Corollary: Benefit of majority is the criterion of justice, when benefits conflict and each one's change of benefit is almost the same.

There are three ways to sacrifice the interests of someone: by force, will or deal. Forcing someone to sacrifice is called struggle. If the goal of the struggle is to increase the total interest and meet the principle of justice, it is called the just struggle. If the total interest is reduced, it is called the unjust struggle. If the sum of interests is unchanged, this struggle does not matter justice and injustice, but it has good and evil. The struggle includes both force and peace. Human society is always inevitably struggling.

Conflicts can cause damages for both parties. To reduce this damage, people hope to find a choice acceptable to both parties. Sacrificing the interests of one party by means of transactions is to allow the beneficiaries to transfer part of the benefits to the victims. This kind of approach can turn interest conflict into benefits unity, which is the most ideal. But can not be realized in all conditions.

The approach to sacrifice the interests of one party by voluntary is called dedication. This often becomes a necessary condition for social development.

It is good for you to damage your own interests and safeguard the interests of others, regardless of the size of the benefits. If you damage the interests of others and safeguard your own interests, then only when benefit is greater than the loss, it may be understood and allowed. To harm others' small profits to safeguard one's own interests, such as using the blood of others to save one's live, is also evil and needs to be compensated by rewards, thanks or other ways.