Man's behaviour, according to Sadr, is categorized into three types of relationships: social, economic and religious. They stem from man's basic relationship to other men, to the environment, and to God. The economic relations, however, are outcome of his inner instinct of self‑love that "always drives him to seek good thins for himself, to secure his interest, and satisfy his needs.  Accordingly, man, in his relationship with the environment, was predisposed to utilize all possible resources to satisfy his needs and increase his pleasure. In due time, he was willing to use animals and plant to help him in his struggle against the environment. Although his essential needs were simple in the early period of history, his mental capacities enabled him to develop new means to help him utilize the resources of the environment. Thus his needs are always expanding due to the complexity of utilizing the resources of the environment.
Man's relationship with others of his kind was the natural outcome of his need to satisfy his desires. The complexity of life, arising from his relationship with the environment, made it difficult for him to cope adequately with his needs. Cooperation with others made the effort to satisfy his needs manageable. Cooperation with others result in a sharing of benefit with all participant in the community.  The inner instinct of self‑love that drove man to create the first community are evident. These instinct gave rise to man's exploitation of his brother.
Because people were not equal in their physical and mental capacities, they obviously differed in their utilization of the resources of the environment. Such differentiation of capabilities is part of the divine plan for bringing about cohesion through the division of labour to the human community. People of different capabilities function in different tasks within the social order.  However, man's desire to maximize his interest drove some men to exploit the situation for their benefit. Human needs were growing due to man's mental and economic development. His experience broadened his capacities to utilize the resources of his environment. His passion to acquire more of the environmental resources for himself became prevalent. Consequently, some men were willing to oppress others to satisfy their greed and egos (both outcome of self‑love). It was then that the human community faced oppression in the form of economic exploitation.
This conflict between social peace and individual instinct of maximizing interest was persistent throughout history. This historical conflict, Sadr argues, is between two classes: those individuals who control the environmental resources (economic and social) and endeavour to protect their interest, and the rest of the society which strives to live in peace and cooperation. Marxist believe the problem originated with a few people controlling economic resources. The only way to bring about peace to the social order is through the revolution of the oppressed class to destroy the special interest of the privileged class. Capitalist, on the other hand, believe such social conflict to be the result of limited natural resources of the environment, which are not sufficient to satisfy the needs of all people.  Thus, social conflict will always be prevalent. Only through incremental and gradual reforms can society hope to manage social conflict from overtaking human progress. On this basis, capitalists oppose any type of social revolution. However, Islam disagrees with both the views and considers environmental resources to be sufficient to satisfy all people's needs.
According to Sadr, the proem rests with the channelling of human nature: how can the instinct of self‑love be directed in a proper manner? Unless a solution emerges to control human desires and deflect the potential for exploitation of others, social order rests on shaky foundations. Therefore, $adr clearly states that the socioeconomic problem is the result of the misconduct of man. He specifies two reasons for the socioeconomic problems: (1) the oppressive character of man, arising from his self‑love; and (2) man's inefficiency in the utilization of economic resources.
According to Sadr's interpretation, the ills stemming from man's oppressiveness in the economic realm of life persist in the form of inequitable distribution of economic resources on the one hand and from inefficient utilization of these resources, which result in underdevelopment of economic resources and their waste. A solution must overcome these two basic ills of the economic behaviour of man. Sadr specifies three components of the Islamic solution: (1) cessation of the various forms of oppression manifest in the unjust distribution of economic resources; (2) disciplining of "human nature to achieve control of the instinct of self‑love; and (3) utilization of economic resources to satisfy the needs of all humanity.
. Al‑Sadr, "Al‑Nizam al‑'Islami muqaranan bil‑nizam al‑ra'smali wa al‑Markisi" (The Islamic System Compared with the Capitalist and the Marxist Systems) in Ikhtarnalak, 160.
. Ibid., 161
[4.] Al‑Sadr, Iqtisaduna (Our Economics) (Beirut: Dir al‑Ta'aruf, 1982), 311313.
. Here Sadr seems to mention the view of Thomas Robert Malthus. He disregards other capitalist economic thinkers who believe that the source of economic problem is the distribution of economic wealth.