The Obligation Basis in Contract Law

In the legal interactions of humans, a contract is made and the people obligate themselves to this contract and the decree is prohibited and deserves compensation, and due to this contract, a person committed for doing something and on the other hand, these obligations have compelling powers that are crystallized in the form of its implementation and are distinguished from ethical promises. Where does the source of obligation come from? In responding to this question, many ideas were raised that each of the opinions has many followers, including the rule of will, constraint, law, justice etc. and among them, the advocates of this theory which emphasize on intention, make the will only the source of the obligation to contract. But it does not seem that the only will of the person who usually seeks to attract personal interests is effective in this obligation and commitment, but along with this individual will, one has to pay attention to the role of the collective will of humans seeking to attract the interests of the people, and finally it is acknowledged.