Reality and levels of reality : can macrology always be based on micrology ?
This contribution to the discussion on the issue concerning the connections between micrology and macrology, an issue which is unseparable from the problem arising when explaining social sciences, has five objectives. First of all, it is shown that the most common definition of micro and macro, based on size, is partial and erroneous. It is in fact necessary to introduce a tri-dimensional theory which takes into account, initially, and above all, the nature of the problem to be solved, then the type of hypothesis or simplifiaction adopted in order to reply, lastly the nature of the observation unit and the analysis which must be appropriate as regards the first dimension. Second, this article proposes to develop a typology based on the three dimensions and to summarize in different categories all sociological and economic theories. Third, it is shown that a large number of debates and controversies among these different theories were due to micro-macro relations. Fourth, there is an analysis of the solutions put forward for the problems arising from these relations, and an explanation why certain theories failed. Fifth, and last, it is shown that not a single theory offers a unique solution to micro-macro relations even though certain theories would appear more applicable than others.