Economic development may be defined as that part of the total social developmental process which results in an increase in per capita real income in any society or segment of society. In other words, economic development is that part of the total process of social change which makes us all richer. It cannot be understood, however, except as part of a total process in society.

The rate of economic development as measured by the rate of increase of per capita real income has varied from negative rates in declining societies to rates of 8-10% per annum in modern Japan. Historically we can distinguish three periods or processes of rapid growth interdispersed at different times and places by slow or even negative growth. The three periods of rapid growth are 1) the transition from the Paleolithic to the Neolithic, 2) the transition from the Neolithic to civilized society, and 3) the transition from civilization to post-civilized society which is going on now.

There are many interesting parallels between the system of development in society and biological evolution. The systems are different enough to make us beware of inexact analogies but they are, similar enough to suggest that they are both examples of a larger process, which has been at work in this part of the universe for a very long time. This is the process of the development of structures of increasing complexity and improbability. This process starts with the evolution of the elements; helium is less probable than hydrogen. It goes on through biological evolution with increasingly complex and improbable forms culminating in man. The human nervous system then takes up the evolutionary task by developing increasing knowledge and complexity of organizations. What we call economic development is only-a single aspect of this cumulative process.

The evolutionary process always operates through mutation and selection and has involved some distinction between the genotype which mutates and the phenotype which is selected. In biological evolution this distinction is very clear, in social evolution much less so; nevertheless, it exists. The genotype is propagated by a process which might be called "printing" or simple reproduction of structure. The gene creates another gene exactly like itself by printing itself, as it were, on the matter around it, just as a page of type can print its essential form on innumerable sheets of paper.

The process by which the genotype constructs the phenotype may be described as "organization". It is this process by which the information contained in the fertilized egg eventually produces the chicken or a human being. In social systems, genotypes consist of such things as maps, blueprints, ideas, books, computers, ideologies, images of the future, prophets, entrepreneurs, and so on which have the capacity of organizing role structures, organizations, patterns of behavior and artifacts. Thus the automobile is a social phenotype originating in the ideas, plans and blueprints in the engineer's office and materializing in the "womb" of the factory. A church is a phenotype produced by the ideas, experiences, and "sacred histories" of its founders and members.

Economic development manifesto itself largely in the production of commodities, that is, goods and services. It originates, however, in ideas, plans, and attitudes in the human mind. These are the genotypes in economic development. This whole process indeed can be described as a process in the growth of knowledge. What the economist calls "capital" is nothing more than human knowledge imposed on the material world. Knowledge and the growth of knowledge, therefore, is the essential key to economic development. Investment, financial systems and economic organizations and institutions are in a sense only the machinery by which a knowledge process is created and expressed. We see this very clearly by contrasting the post-war history of Japan and Germany where the material capital was largely destroyed but the knowledge was not, and which therefore recovered with great rapidity from the destruction of the war, with the history of many other countries which did not suffer physical destruction but where the knowledge base for economic development did not exist.

A problem of great current interest is the role of revolution in the evolutionary process, especially of course in economic development. The term is carelessly used and sometimes means merely an unusually rapid rate of change. More exactly it means some qualitative change in the structure of the system, which may give rise to more rapid rates of change. I have sometimes called these "gear changes" in the evolutionary process and there have been many of them in both biological and social evolution, the greatest of which was the development of man himself, which was a truly revolutionary change in this part of the universe. Another name for this type of phenomenon is an "acceleration".

Political revolutions, that is, the substitution of one governing group for another may or may not be accelerations in the above sense. Where the group which is aware of and favorable towards development replaces a group which is not favorable to development, an acceleration may take place. It is important to recognize, however, that revolutions are a "cost" and the acceleration which may or may not follow is the "return". There is real danger in what might be called sentimental revolutionism which idealized the process of revolution in itself. This may easily lead to what might be called "high cost revolutions" and if a society can get an acceleration without a revolution it is all the
better off.