This is what Yves Guyot, for example, does in Les Principes de 1789, Paris, 1894, when he declares, in the name of individualist psychology, that “socialism is restrictive and individualism expansive.” This thesis is, moreover, in part true, if it is transposed.
The vulgar psychology, which answers the purposes of M. Guyot (La Tyrannie socialiste, liv. III, ch. I.), is content with superficial observations. It declares, for instance, that if the laborer works twelve hours, he will produce evidently a third more than if he works eight hours, and this is the reason why industrial capitalism has opposed and does oppose the minimum programme of the three eighths—eight hours for work, eight hours for sleep and eight hours for meals and recreation.
A more scientific physio-psychological observation demonstrates, on the contrary, as I said long ago, that “man is a machine, but he does not function after the fashion of a machine,” in the sense that man is a living machine, and not an inorganic machine.
Every one knows that a locomotive or a sewing machine does in twelve hours a quantity of work greater by one-third than it does in eight hours; but man is a living machine, subject to the law of physical mechanics, but also to those of biological mechanics. Intellectual labor, like muscular labor, is not uniform in quality and intensity throughout its duration. Within the individual limits of fatigue and exhaustion, it obeys the law which Quetelet expressed by his binomial curve, and which I believe to be one of the fundamental laws of living and inorganic nature. At the start the force or the speed is very slight—afterward a maximum of force or speed is attained—and at last the force or speed again becomes very slight.
With manual labor, as with intellectual labor, there is a maximum, after which the muscular and cerebral forces decline, and then the work drags along slowly and without vigor until the end of the forced daily labor. Consider also the beneficient suggestive influence of a reduction of hours, and you will readily understand why the recent English reports are so unanswerable on the excellent results, even from the capitalist point of view, of the Eight-Hour reform. The workingmen are less fatigued, and the production is undiminished.
When these economic reforms, and all those which are based on an exact physio-psychology, shall be effected under the socialist regime—that is to say, without the friction and the loss of force that would be inevitable under capitalist individualism—it is evident that they will have immense material and moral advantages, notwithstanding the a priori objections of the present individualism which can not see or which forgets the profound reflex effects of a change of the social environment on individual psychology.
 ICILIO VANNI, La funzione practica della filosofia del diritto considerata in se e in rapporto al socialismo contemporaneo, Bologne, 1894.