We now see that the many centuries that filled the history of civilization were a necessary preparation for socialism, a slow struggle to escape from nature's slavery, a gradual increase of the productivity of labor, up to the point where the necessaries of life for all may be obtained almost without exertion. This is the prime merit of capitalism and its justification, that after so many centuries of hardly perceptible progress it taught man to conquer nature by a rapid assault. At the same time it set loose the forces of production and finally transformed and bared the springs of the productive process to such a degree that they easily could be perceived and grasped by the human mind; this was the indispensable condition for the control of this process.
As never since the first advent of production of commodities there has been such a fundamental revolution, it must necessarily be accompanied by an equally fundamental spiritual revolution. This economic revolution is the conclusion of the long period of class antagonisms and of production of commodities; it carries with it the end of the dualist and supernatural thoughts arising from this source. The mystery of social processes passes away with this period, and the spiritual expression of these mysteries must necessarily disappear with it. The slow development of human thought from ignorance to an ever increased understanding thereby ends its first chapter. This signifies the completion and conclusion of philosophy, which is equivalent to saying that philosophy as such passes out of existence, while its place is taken by the science of the human mind, a part of natural science.
A new system of production sheds its light into the minds of men already before it has fully materialized. The same science which teaches us to understand and thereby to control the social forces, also unfetters the mind from the bewitching effects of those forces. It enables him even now already to emancipate himself from traditional superstitions and ideas which were formerly the expression of things unknown. We may anticipate with our mind the coming time. And thus the ideas which will then dominate are already even now growing within us in a rudimentary form corresponding to the present actual economic development. By this means we are even now enabled to overcome the capitalist philosophy in thought and to soberly and clearly grasp the matter-dependent nature of our spirit.
The completion and the end of philosophy need not wait for the realization of socialist production. The new understanding does not fall from heaven like a meteor. It develops with the social-economic development, first imperfectly and imperceptibly, in a few thinkers who most strongly feel the breath of the approaching time. With the growth of the science of sociology and with that of its practical application, the socialist labor movement, the new understanding simultaneously spreads and gains ground step by step, waging a relentless battle against the traditional ideas to which the ruling classes are clinging. This struggle is the mental companion of the social class struggle.
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The methods of the new natural science had already been practiced for a few centuries before the new theory was formulated. It first found vent in the expression of surprise at the great confidence with which men assumed to predict certain phenomena and to point out their connections. Our experience is limited to a few successive observations of the regularity or coincidence of events. But we attribute to natural laws, in which are expressed causal relations of phenomena, a general and necessary applicability which far exceeds our experience. The English thinker Hume was the first who clearly expressed and formulated the question—since called the problem of causality—why men always act in this manner. But as he believed the reason for such action should be sought in the nature of experience alone, experience being the only source of knowledge, and as he did not further investigate the special and distinct part played by the nature of the human mind in this experiential connection, he could not find any satisfactory answer.
Kant, who made the first important step toward the solution of this question, had been trained in the school of rationalism which then dominated in Germany and which represented an adaptation of mediæval scholasticism to the requirements of increased knowledge. Starting from the thesis that things which are logical in the mind must be real in nature, the rationalists formulated by mere deduction general truths about god, infinity and immortality. Under the influence of Hume, Kant became the critic of rationalism and thus the reformer of philosophy.
The question, how it is that we have knowledge of generally applicable laws in which we have implicit confidence—such as mathematical theses, or the maxim that every change has a cause—was answered by Kant in this way: Experience and science are as much conditioned on properties inherent in the organization of our mind as on the impressions of the outer world. The former properties must necessarily be contained in all experience and science. Therefore everything dependent on this common mental part of science must be perfectly certain and independent of special sense impressions. Common to all experience, and inseparable from it, are the pure sense-conceptions (reine Anschauungsformen), such as space and time, while the many experiences, in order to succeed in forming understanding and science, must be connected by the pure mind-conceptions (reine Verstandesbegriffe), the so-called categories; among the latter also belongs causality.
Now Kant explains the necessity and general applicability of the pure sense and mind conceptions by the fact that they arise from the organization of our mind. Accordingly, the world appears to the senses as a succession of phenomena in time and space. Our reason transforms these phenomena into things which are welded into one aggregate nature by laws of cause and effect. On the things as they really are in themselves, in the opinion of Kant, these pure conceptions cannot be applied. We know nothing of them and can neither perceive nor reconstruct them by reason, because "in themselves" they are wholly beyond reason and knowledge.