Abstract

Since 1992, the World Conference on Environment and Development, mankind has started a new era of sustainable development. However, the current focus of countries is still the economic growth, the current mainstream economics is still the classical economics（Neoclassical economics and Macroeconomics）. There is a big conflict between The“single growth type”economic model that based on the classical economics theory and the“ecological economic social coordinated development”economic model that based on the sustainable development theory, even worse, they are opposite. Sustainable development focuses on the human overall interests, the interests of future generations, the ecological interests of the earth, while the classical economics which based on the“rational economic man”hypothesis is concerned about how to maximize the own benefit of the“economic man”, and the concerns about the interests other than self-interest is“irrational”. Under the guidance of this theory, the actual result is the continuous growth of the global economic, the scarcity of the resources, the deterioration of the environment, the more and more severe disasters and the increasing difficulties of reconciling the conflict between humans. The outbreak of the global economic crisis and the global terrorist activities have shown that the world economic development exists some problems which need to be adjusted. To get rid of the current global dilemma, the development of mankind must follow a path of sustainable and harmonious development and the current economic development model is bound to move from the“growth paradigm”to the“sustainable development paradigm”. In practice, mankind will be out of the era of industrial civilization at the cost of conquering, plundering and sacrificing the ecological environment, and step into the era of ecological civilization that protects and constructs the ecological environment and reconstructs the harmonious coexistence and common prosperity of man and nature. As the time goes, the Economics theory must be improved with the needs of human development, rather than“procrustean”method of which makes our economic activities to adapt to the original economic theory. Therefore, the reality requires us to find a transition from a single economic growth model to a sustainable development model, to find a theoretical system that can be transformed from traditional economics to sustainable development economics, so that we humans can really walk onto the road of sustainable development.

In recent years, many Chinese and foreign scholars has done a lot of researches on how to build a new economic theory to meet the needs of sustainable development and they made lots of achievements. But, there is still lack of a theoretical basis which derives from the classical economics but beyond and contains it at the same time, because only along this line of thought, can the transformation to the sustainable development economics be smooth under the current economic development model. On the basis of previous studies, this paper proposes a new way to construct the theoretical foundation of the sustainable development economics theory, and explores the logical line which is on the basis of such theory, proposes the sustainable development model of the“trinity theory”. The main contents of the research include the following aspects：

1. The requirements of the sustainable development theory to the innovation of the economics theory

Since the industrial revolution, according to the industrial development model, human material civilization has made great progress and created a lot of material wealth, but it also brought disasters to mankind, the conflict between the economic development and the environment has become more and more serious, the sustainable development has became the inevitable development model of mankind. The new development model cannot be developed from the old economic theory, the sustainable development model needs new innovation of the economics theory to adapted to, the economic development needs new economic theory to guide.

2. The limitations of the“rational economic man”hypothesis

Because of the fundamental flaws in theory, the classical economics cannot meet the needs of the new era of the economic development. The classical economics is mainly characterized by the disjunction of the economic and ecological, its theory is based on the hypothesis of the inexhaustible resources and the infinite carrying capacity of the ecological environment, it regards the economy as a isolated system which doesn't depend on the external environment, so called“empty world”by Daly, so it can grow infinitely. In fact, the current economic development of mankind has entered from“empty world”to“full world”, Economic development is constrained by environment and resources, and economic development needs to be sustainable regulation. The sustainable development regulation is contradictory to the paradigm of the“rational economic man”, the main reasons are as follows:（1）bounded rationality of economic subject;（2）imperfectness and asymmetry of information;（3）absence of natural subject;（4）the fail market regulation of the environmental resources, and so on. These conflicts have forced an increasing number of economists to try to reinterpret the connotation of economic man.

3. the introduction of social rationality, to build“social economic man”hypothesis

The theoretical cornerstone of the classical economics is“rational economic man”hypothesis, in this hypothesis, everyone is only concerned with their own interests, the goal is to maximize individual interests. The core of sustainable development is the“intergenerational equity”, which requires humanity to meet the interests of the contemporary people, but also not harm the interests of future generations. This shows that the theoretical basis of traditional economics and sustainable development is out of line. Therefore, we need to extend the classical economic theory to meet the requirements of sustainable development. In order to do this, redefining the individual rationality, assuming the individual rationality is dual, which means caring about self-interest and the benefit of the related group at the same time. Therefore, the individual has both self-interest rationality, but also has social rationality. People with this“dual rationality”are called“socioeconomic man”. On the basis of the hypothesis of“social economic man”, the framework of sustainable development economics is constructed. The“social economic man”hypothesis transcends the“rational economic man”hypothesis, which extends the individual with a single selfbenefiting rationality to an individual with both self-benefiting rationality and social rationality. In the“social economic man”hypothesis, the individual is still considered as an“economic man”in the economic life, but is a“social economic man”that evolved more than“rational economic man. ”

4. The logic main line of the sustainable development economics with the basis of“social economic man”

In the problems of the sustainable development of the environment and ecology, it is proved that there are two situations, one is the market failure and the other one is the government failure, its fundamental reason is the existence of information barriers and the opportunistic behavior. To reduce market failure and government failure, the most important thing is how to reduce information barriers and opportunism, which is difficult to solve by the classical theory based on the“rational economic man”hypothesis. Under the hypothesis of“social economic man”, we have explored the essential meaning of social capital and the foundation of civil society organization, so as to put forward a new logical route for the theory of sustainable development. Civil society organizations are formed on the basis of individual social rationality, and they are opposed to opportunism. In addition, community organizations have their own advantages in reducing information barriers. The reason that the community organizations can compensate government and market failure to some extent is the existence of social capital within social organizations, so that they can choose effective institutional arrangements to avoid moral hazard and adverse selection through social capital such as trust relationship. There is a“voluntariness failure”in the community organizations, so that it requires the tripartite cooperation of the market, government and community organizations. Only if the“communitymarket-government”trinity of the economic complex can be built can the sustainable development be achieved.

5. The application analysis of sustainable development economics based on the“social rationality”

With the logic main line of social economy man-social capital-community organization, we analyzed the core problem of sustainable development. Including the analysis of externalities, the analysis of natural resources, the analysis of intra-generation fairness and the analysis of intergenerational fairness and so on. Based on the hypothesis of“social economic man”, in the analysis of externalities, The concept of externality is put forward, and different solutions are put forward for three kinds of externality. In the analysis of natural resources, we put forward the complementary theory; In intra-generational fair analysis of natural resources, we put forward the contradiction between“overall value”and“the decomposing value”; In the intergenerational equity analysis, we put forward that competition is the key to the intergenerational imbalance, the intergenerational equity can be achieved only if the cooperation can be strengthened. Through the analysis of the main problems of sustainable development, the new economic analysis paradigm based on the hypothesis of“social economic man”has been initially verified.

Keywords: sustainable development; social rationality; social economic man; social capital; civil society organization