(2) While this extreme denial of the possibility of laws of human action is logically possible, the actual success of those sciences which deal with human behaviour in the statistical way forbids us to accept it. The success of these sciences shows that human behaviour, considered in the gross, does exhibit certain approximate uniformities. But there seems to be no means of proving that all aspects of human behaviour would show such uniformity if considered in gross in the same fashion. It is at least conceivable that some social activities would fail to exhibit approximation to an average value, no matter how extended the area and period taken as the basis of investigation. We might conceivably have to admit that there are departments of social life for which no “laws” can be formulated. If we disregard this possibility in practice, the reason is a methodological one. It is our _interest_ to discover such uniformities, and therefore, as failure _may_ only mean a temporary check to the success of our investigations, we properly make it a rule of method to assume that it is no more than this. We treat all sequences as capable, by proper methods, of reduction to uniformity, for the same reason that we treat all offenders as possibly reclaimable. We desire that they should be so, and we cannot prove they are not so, and we therefore behave as if we knew they were so. A word may be said as to the nature of the practical need upon which the postulate of Uniformity is based. As we have previously seen, the allied postulate of Causality arose from the practical need of devising means for the control of natural processes. But the causal postulate alone is not enough to satisfy this need. For even if we can assume that every event is determined, sufficiently for practical purposes, by its antecedents, and thus that the knowledge of those antecedents, when obtained, is a knowledge of the means to its production, our practical command over the production of the event is not yet assured. For we can have no general confidence in our power to produce the event by employing the ascertained means, so long as it is possible that the result may on each occasion be affected by variations too minute for our detection, or for other reasons not accessible to our perception. We need to be assured that what seems the same to us is, for practical purposes, the same, and so that the employment of the _same_ means may be trusted to lead to the same result. This is the condition which is expressed in an abstract form by the principle of Uniformity, which states that the course of natural processes conforms to general laws; in their actual application to the concrete processes of actual nature these laws are properly practical rules for the production of effects, and their inviolability means no more than that we may successfully treat as the same, in their bearing on the results in which we are interested, things which appear the same in relation to certain