There is an interest relationship between people. 1, when their own interests are inconsistent with those of others, people always tend to satisfy their own interests, which is the nature of any creature. So in order to satisfy their own interests, there is a struggle. They use war, plunder, rule and use to realize their own interests. 2. When one's own interests are consistent with those of others, people's interests are closely linked. In order to satisfy one's own interests, there will be cooperation to realize one's own interests through peace, equality, freedom and mutual assistance. 3, the question is whether the interests between people are consistent. In capitalist society, individual interests are based on sacrificing the interests of others and aim at obtaining unlimited interests. Those interests are illegal because they are at the expense of others' interests. Finally, most people are even deprived of the benefits of survival. Therefore, Marx put forward the idea of productism, hoping to link the interests of all people together, so that there would be no struggle. Only by uniting can everyone's interests be met and human beings develop harmoniously. Nowadays, there are both struggles and alliances between people, which are achieved as the rich unite to oppress the poor and the poor unite against the rich. In short, people tend to cooperate when their interests are consistent and equal, and tend to struggle when their interests are inconsistent and unequal. It is such a state.