Now, it happens that the relation of sufficient reason enters very substantially into human conduct. It is this element of discriminating forethought that distinguishes human conduct from brute behavior. And since the economist’s subject of inquiry is this human conduct, that relation necessarily comes in for a large share of his attention in any theoretical formulation of economic phenomena, whether hedonistic or otherwise. But while modern science at large has made the causal relation the sole ultimate ground of theoretical formulation; and while the other sciences that deal with human life admit the relation of sufficient reason as a proximate, supplementary, or intermediate ground, subsidiary, and subservient to the argument from cause to effect; economics has had the misfortune-as seen from the scientific point of view-to let the former supplant the latter. It is, of course, true that human conduct is distinguished from other natural phenomena by the human faculty for taking thought, and any science that has to do with human conduct must face the patent fact that the details of such conduct consequently fall into the teleological form; but it is the peculiarity of the hedonistic economics that by force of its postulates its attention is confined to this teleological bearing of conduct alone. It deals with this conduct only in so far as it may be construed in rationalistic, teleological terms of calculation and choice. But it is at the same time no less true that human conduct, economic or otherwise, is subject to the sequence of cause and effect, by force of such elements as habituation and conventional requirements. But facts of this order, which are to modern science of graver interest than the teleological details of conduct, necessarily fall outside the attention of the hedonistic economist, because they cannot be construed in terms of sufficient reason, such as his postulates demand, or be fitted into a scheme of teleological doctrines.