It is necessary to note that the maximization of benefit is different from the Majority Rule. For instance, it is to sacrifice benefit of majority that many people contribute money to save a life, but also maximization of the benefit, because the changes of benefits of different people are different.

The Greatest Happiness Principle of Mill and Bentham²⁶ can be concluded from upper conclusion, when the change of each one's benefit is the same.

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

It is always possible for one side to sacrifice when benefit of different people conflict, no matter whether the total of benefit can rise. There are three ways to sacrifice: by force, will or deal. It is struggle to sacrifice one's benefit by force. It is justice struggle when the aim is to raise the total of benefit, which fit the upper theorem, and the opposite is not justice. The struggle cannot be designated as justice or not but can be designated as good or evil, when the total of benefit cannot rise or avoid to fall.

Struggles include peaceful ones or not peaceful ones. Struggle is not possible to avoid in society, and it is possible to trigger positive feedback, namely vicious cycle or revenge on each other, which can always bring catastrophe.

Consequently, a lot of laws, conventions and rules are created to decrease the loss and realize fair play as far as possible. Rules also make it easy for people to make decisions, prevent assessing gains and losses from start every time. Rules are useful to realize maximization of benefit, though no present rules are prior criterion of justice. The rule, which is not able to help us to raise benefit or decrease loss, is not justice.

Theorem: The law, moral and all other rules are justice only when they are able to help people to raise benefit or decrease loss.

This is the basis of Rule Utilitarianism which Jacques Thiroux mentioned.²⁷ 

To sacrifice one's benefit by deal means to alienate some interest of beneficiary to victim. In this way benefit contradiction may be transformed to unification, which is ideal but not possible in all kinds of conditions. To sacrifice by will is dedication, which is necessary for social progress. But it is not so good when there are too many dedications.

It is evil to harm others no matter how much it does, and is possible to be understood and admitted only when gain is bigger than loss. It is evil to save yourself with blood of others, unless it is admitted in advance and compensated.

The practical imperative of Immanuel Kant is, “Act in such a way that you always treat humanity, whether in your own person or in the person of any other, never simply as a means, but always at the same time as an end.”²⁸ This rule is not right,sometimes people can be treated as means to reach other's aim. For example, there are many medical experiments using people as object, surely enough without danger of life. Otherwise people should not be used, unless there is no other ways and it is able to save many lives. Generally, however, solutions are able to be found, like using animals to do medical experiments.