IF we have proved to our satisfaction that the breakdowns of civilizations are not brought about by the operation of cosmic forces outside human control, we have still to find the true cause of these catastrophes; and we will first consider the possibility that these breakdowns are due to some loss of command over the society's environment. In attempting to solve this problem we will employ the distinction that we have already made between two kinds of environment: the physical and the human.
Do civilizations break down owing to loss of command over their physical environments? The degree of command over its physical environment possessed by any society can be measured, as we have already pointed out, by its technique; and we have already ascertained, while studying the problem of 'growth', that, if we set ourselves to plot out two sets of curves—one set representing the vicissitudes of civilizations and the other the vicissitudes of techniques—the two sets of curves not only fail to correspond but display wide discrepancies. We have found cases of technique improving while civilizations remain static or decline and cases of technique remaining static while civilizations are in movement, either forward or backward as the case may be. i We have therefore already gone a long way towards proving that loss of command over physical environment is not the criterion of the breakdowns of civilizations. In order to complete our proof, however, we have to show that, in cases where the breakdown of a civilization has been coincident with a decline in technique, the latter has not been the cause of the former. We shall find, as a matter of fact, that the decline in technique has been, not a cause, but a consequence or symptom.
When a civilization is in decline it sometimes happens that a particular technique, that has been both feasible and profitable during the growth-stage, now begins to encounter social obstacles and to yield diminishing economic returns; if it becomes patently unremunerative it may be deliberately abandoned. In such a case it would obviously be a complete inversion of the true order of cause and effect to suggest that the abandonment of the technique in such circumstances was due to a technical inability to practise it and that this technical inability was a cause of the breakdown of the civilization.____________________