The issue of the basis of contracts was strongly marked by the doctrine of autonomy of will. However, changes in society have led to a new stage in the evolution of legal thinking. Social interests, interests other than those derived from the doctrine of autonomy of will, became part of the concerns of contract law, highlighting the greater role of law in the new notion of contract.
According to this new conception, the autonomy of the will would not be the only source of obligation. The autonomy of the will should be understood as self-regulation in the interests of the parties, and therefore, an act of private autonomy, but this act should be performed under the conditions allowed by law, as only in this way would the contract have legal effectiveness. In this way, the law supersedes the autonomy of the will.
This new point of view destroys the position of supremacy of the individual and free will in law. Along with individual will, other values share the basis of contracts, such as good faith, trust, equity and security in legal relations in the new contractual theory.
Thus, if in the classical conception of the contract the internal will should prevail over the declared will, in the new contractual theory, the preference will fall on the declared will and the appearance of will, in the so-called theory of trust.
Cláudia Lima Marques registers that:
Socialized contract law rediscovers the role of law, which will no longer be merely interpretative or supplementary, but binding. The law will protect certain social interests and will serve as a limiting instrument on the power of will.
In our opinion, this desired contractual justice lies precisely in the equivalence of benefits or sacrifices, in the protection of trust and good faith on both sides.
Will remains one of the foundations of contracts, but it finds limitations in the social function of the contract, in good faith, in equity. And the State will limit the autonomy of the will through rules and also through the review or extinction of contracts through the courts.
The law develops a contractual theory with a social function, that is, it recognizes the influence of the social aspect of the contract, including justice in the concrete case. In this new theory there is great relevance of good faith and also objective good faith; an action of the contracting parties that is consistent with reasonable expectations, that is motivated by loyalty and prohibiting abuse. Good faith embraces an ethical principle, based on loyalty, trust and honesty.
It can be said that in the most modern types of contracts, such as consumer contracts, the will of the parties, in addition to being relativized, is even dispensable. In fact, there are social relationships that imply obligations, and actually living itself is even legalized. And this is not surprising when it comes to extra-contractual civil liability, which is one of the ways in which living implies obligations for third parties regardless of our will. But of course there are limits to the legalization of social contact, and this limit is similar to that of the current contract: good faith, the principle of trust, equity.
Society must be responsible for the social well-being of citizens and regulate the rights of individuals, the consequence of which is the relativization of subjective rights with the use of the principle of social function in private relations.
Even if the parties to a contract sign a private patrimonial contract, society can interfere in this private relationship to ensure the balance of this contract to promote the harmony of social relations, even if it has to mitigate the autonomy of the will.
Taisa Maria Macena de Lima 8 summarizes the principle of social solidarity well:
Naturally, the principle of social solidarity does not mean disregard for individual rights, but a tendency to balance the value of human dignity and collective values.
Thus, the social aspect becomes present in all rights and duties signed by the contracting parties that must be carried out functionally, but without straying from the economic and social purposes for which the contract was entered into. From the point of view of sociality, it appears that contractual law, due to the new socio-economic realities, needed to adapt and acquire a new function, which means the realization of justice and contractual balance.
Socialization is manifested in the interventionism of the State in the life of contracts and in the change of paradigms itself, which will eventually lead to greater use of the principles of good faith and contractual revision in the formation and execution of obligations.
This perspective is linked to the new understanding of the will in the business phenomenon and the ‘function of the contract’, the latter as an autonomous source of obligatory relationships. In this way, the contract has the main function of safeguarding justice and equity.