The Kantian moralist, like the theologian, is forbidden by the logic of his system to admit the possibility of moral progress. If the moral law is categorical, that is, unlimited by any special purpose, if it exists within us, eternal and immutable as the stars above us, we should be hard put to it to say how this unalterable block, placed in our souls we know not how or by whom, could receive an impetus to progressive development, or in what way this development could be carried out. That which is categorical is absolute, and the concept of progress in the absolute, as in the infinite and the eternal, has no sense. But whoever regards Morality from the biological and sociological point of view is forced to assert its progress, just as the dogmatic mystic, who believes in the categorical imperative, is forced to deny it.
Let us recapitulate the fundamental concepts. Regarded biologically Morality is Inhibition, the development of which is of the greatest importance to the individual, as it enables him not to waste the living force of his cell plasm and of his organs in sterile reflex movements, but to store it up and hold it ready for useful purposes. The stronger his power of inhibition the better he is armed for the struggle for existence, and the better he is armed the more efficient he is. Denial of the progressive development of Inhibition implies a denial that modern man can maintain himself with more ease and security against Nature and hostile or injurious natural phenomena, and that he is more successful in competition with other men than his predecessors on earth. But this latter denial is obviously nonsense. The only individuals who do not take part in progressive development are the degenerates. They are organically inferior, their faculty of inhibition is defective or altogether lacking, they are slaves of impulses which their will and intelligence have no means of controlling, they are the outcome of morbidly arrested or retrograde development, they are the victims and refuse of a civilization too intensive, too exhausting and wearing for some men, and they are destined to fall out of the ranks of a race moving majestically forward and to lie helplessly by the roadside.