Abstract
This paper is concerned with the problem of causal ordering, that is, the problem of when an input output relation can be established for a system. The problem is already discussed by H.A. Simon. According to Simon, the causal ordering is not given by a logical implication but determined by the structure of a model and is essentially a reflection of the mechanisms specifying the structure. We stand on the same viewpoint as his. We insist that Simon's mechanism is reflected in the time sequence of events in a dynamic system and hence give the definition of causal ordering by using a non-anticipation criterion.
The former part of the paper disusses the definition of causal ordering referring to Simon's paper. The lattar part is concerned with the asymmetry problem of the causal ordering defined above, that is, the problem of whether or not an input output relation can be inversed. Since it is difficult to solve the problem in general, we treat a basic linear system and a general system with a specific structure and show that when a system is strongly non-anticipative, its causal ordering is asymmetry.
