Only a few personalities in the second half of the nineteenth century attempted to find a firm foundation for the relation of a conception of the self-conscious ego toward the general world picture by going deeply into Hegel's mode of thought. One of the best thinkers along these lines was Paul Asmus (1842–1876), who died as a young man. In 1873 he published a book entitled, The Ego and the Thing in Itself. In it he shows how it is possible, through Hegel's approach to thinking and the world of ideas, to obtain a relation of man toward the essence of things. He explains in an ingenious way that we have in man's thinking an element that is not alien to reality but full of life and fundamentally real, an element on which we only have to concentrate in order to arrive at the essence of existence. In a most illuminating way he describes the course of the evolution of world conception that began with Kant, who had seen in the “thing in itself” an element that was alien and inaccessible to man, and led to Hegel, who was of the opinion that thought comprised not only itself as an ideal entity but also the “thing in itself.” Voices like this found scarcely a hearing. This became most poignantly clear in the slogan, “Back to Kant,” which became popular in a certain current of philosophical life after Eduard Zeller's speech at the University of Heidelberg, On the Significance and Task of the Theory of Knowledge.
The conceptions, partly conscious and partly unconscious, which led to this slogan, are approximately as follows. Natural science has shaken the confidence in spontaneous thinking that means to penetrate by itself to the highest questions of existence, but we cannot be satisfied with the mere results of natural science for they do not lead beyond the external view of things. There must be grounds of existence concealed behind this external aspect. Even natural science itself has shown that the world of colors, tones, etc., surrounding us is not a reality outside in the objective world but that it is produced through the function of our senses and our brain (compare above, to Part II Chapter III). For this reason, it is necessary to ask these questions: In what respect do the results of natural science point beyond their own limits toward the higher problems: What is the nature of our knowledge? Can this knowledge lead to a solution of that higher task? Kant has asked such questions with great emphasis. In order to find one's own position, one wanted to study how he had approached them. One wanted to think over with the greatest possible precision Kant's line of thought, attempting to avoid his errors and to find in the continuation of his ideas a way that led out of the general perplexity.
A number of thinkers endeavored to arrive at a tenable goal, starting from Kantian points of departure. The most important among them were Hermann Cohen (1842–1916), Otto Liebmann (1840 – 1912), Wilhelm Windelband (1848–1916), Johannes Volkelt (1842–1930) and Benno Erdmann (1851–1921). Much perspicacity can be found in the writings of these men. A great deal of work was done inquiring into the nature and extent of the human faculty of knowledge. Johannes Volkelt who, insofar as he was active as an epistomologist, lives entirely within this current, also contributed a thorough work on Kant's Theory of Knowledge (1879) in which all problems characterizing this trend of thought are discussed. In 1884 he gave the inaugural address for his professorship in Basel in which he made the statement that all thinking that goes beyond the results of the special empirical sciences of facts must have “the restless character of seeking and searching, of cautious trial, defensive reserve and deliberate admission.” It should be an “advance in which one must partly withdraw again, a yielding in which one nevertheless holds on to a certain degree” (On the Possibility of Metaphysics, Hamburg & Leipzig, 1884).
This new attempt to start from Kant appears in a special light in Otto Liebmann. His writings, Contributions Toward the Analysis of Reality (1876), Thoughts and Facts (1882), Climax of Theories (1884), are veritable models of philosophical criticism. Here a caustic mind ingeniously discovers contradictions in the worlds of thought, reveals as half truths what appear as safe judgments, and shows what unsatisfactory elements the individual sciences contain when their results appear before the highest tribunals of thought. Liebmann enumerates the contradictions of Darwinism. He reveals its insufficiently founded assumptions and its defective thought connections, maintaining that something is needed to fill in the gaps to support the assumptions. On one occasion he ends an exposition he gives of the nature of living organisms with the words:
Plant seeds do not lose their ability to germinate after lying dry for ages, and grains of wheat found in Egyptian mummy cases, after having been hermetically sealed and buried for thousands of years, when sowed in a moist soil, thrive excellently. Wheel animalcules (rotatoria) and other infusoria that have been gathered completely dried up from a gutter pipe are newly revived by rain water. Even frogs and fishes that have turned into ice cakes in freezing water revive when carefully thawed out. All these facts are capable of completely opposite interpretations. . . . In short, every form of categorical denial in this matter would be crude dogmatism. Therefore, we discontinue our argument.
This phrase, “We discontinue our argument,” really expresses, even if it does not do so literally, every final thought of Liebmann's reflection. It is, indeed, the final conclusion of many recent followers and elaborators of Kantianism. They do not succeed in doing more than emphasize that they receive the things into their consciousness. Therefore, everything that they see, hear, etc., is not outside in the world but within themselves and they are incapable of deciding anything concerning the outside. A table stands before me, argues the Neo-Kantian, but, really, this only seems to be so. Only a person who is naively concerned with problems of philosophy can say, “Outside myself is a table.” A person who has overcome that naïveté says, “An unknown something produces an impression within my eye; this eye and my brain make out of the impression the sensation brown. As I have this sensation brown not merely at an isolated point but can let my eye run over a plane surface and four columnar forms, so the brownness takes the shape of an object that is this table. When I touch this table, it offers resistance. It makes an impression on my sense of touch, which I express by attributing hardness to the picture that has been produced by the eye. At the suggestion of some “thing in itself” that I do not know, I have therefore created this table out of myself. The table is my mental content. It is only in my consciousness.
Volkelt presents this view at the beginning of his book on Kant's Theory of Knowledge:
The first fundamental condition that the philosopher must clearly realize is the insight that, to begin with, our knowledge extends to nothing more than our conceptions. Our conceptions are the only things that we immediately and directly experience, and for just that reason that we experience them immediately, even the most radical doubt cannot deprive us of the knowledge of them. But the knowledge that goes beyond my faculty of conception is not protected from doubt. (I use this expression here always in its most comprehensive sense so that all physical events are included in the term.) Therefore, all knowledge that goes beyond the conceptions must be marked as doubtful at the outset of the philosophical reflection.
Otto Liebmann also uses this thought to defend the statement: Man can no more know that the things he conceives are not, than he can know positively that they are. “For the very reason that no conceiving subject can escape the sphere of its subjective imagination, because it can never grasp and observe what may exist or not exist outside its subjectivity, leaping thereby over its own consciousness and emancipating itself from itself. For this reason it would also be absurd to maintain that the object does not exist outside the subjective conception” (O. Liebmann, Contributions toward the Analysis of Reality).
Both Volkelt and Liebmann nevertheless endeavor to prove that man finds something in the world of his conceptions that is not merely observed or perceived, but that is added to the perception by thought — something that at least points toward the essence of things. Volkelt is of the opinion that there is a fact within the conceptual life that points to something that lies outside the life of conception. This fact consists in the logical necessity with which certain conceptions suggest themselves to man. In his book, The Sources of Human Certainty that appeared in 1906, we read Volkelt's view:
If one seeks the basis of the certainty of our knowledge, one finds two points of origin, two sources of certainty. Even if an intimate cooperation of both sources of certainty is necessary if real knowledge is to result, it is nevertheless impossible to reduce one source to the other. The one source of certainty is the self-assurance of consciousness, the awareness of the facts of my consciousness. That I am consciousness is just as true as the fact that my consciousness testifies to the existence of certain processes and states, certain contents and forms. Without this source of certainty there would be no cognitive process; it supplies the material through the elaboration of which all knowledge is produced. The other source of certainty is the necessity of thought, the certainty of logical compulsion, the objective consciousness of necessity. With it something absolutely new is given that cannot possibly be derived from the certainty of our self-awareness in consciousness.
Concerning this second source of certainty, Volkelt expresses himself in his book mentioned above as follows:
The immediate experience allows us to become aware of the fact that certain combinations of concepts show a peculiar form of compulsion to be inherent in them that is essentially different from all other kinds of compulsion that are associated with conceptions. This compulsion forces us to think certain concepts as belonging together, not merely in the conscious process in which we are aware of them but also in a corresponding objective interconnection, independent of the conscious conceptions. Furthermore, this compulsion does not force us in a manner to suggest that we should forfeit our moral satisfaction or our inner happiness, our salvation and so forth, but it contains the suggestion that objective reality would have to annihilate itself in itself, would have to lose its possibility of existence if the opposite of what it prescribes as a necessity were to take place. What distinguishes this compulsion then is that the very thought of the opposite of that necessity forcing itself upon us, would be experienced as a call that reality should revolt against the conditions of its existence. This peculiar, immediately experienced compulsion is generally called logical compulsion or thought necessity. The logically necessary reveals itself directly as an announcement of the object itself. It is the peculiarly meaningful significance, the reason-guided illumination that is contained in everything logical, that bears witness with immediate evidence of the objective, real validity of the logical connections of concepts. (Kant's Theory of Knowledge, pp. 208 ff.)
Otto Liebmann confesses toward the end of his essay, The Climax of Theories, that in his opinion the whole thought structure of human knowledge, from the ground floor of the science of observation up to the most airy regions of the highest hypotheses of world conception, is permeated by thoughts that point beyond perception. “Fragments of percepts must first be supplemented by an extraordinary amount of non-observed elements linked together and connected in a definite order according to certain operations of the mind.” But how can one deny that human thinking has the ability to know something through its own activity as long as it is necessary to resort to this activity even if one merely wants to obtain order among the facts of the observed precepts? Neo-Kantianism is in a curious position. It would like to confine itself within the boundaries of consciousness and within the life of conception, but it is forced to confess that it is impossible to take a step “within” these boundaries that does not lead in all directions beyond those limits. Otto Liebmann ends the second booklet of his Thought and Facts as follows:
If, on the one hand, seen from the viewpoint of natural science, man were nothing but animated dust, then, on the other, all nature, as it appears in space and time, when seen from the only viewpoint that is immediately accessible and given to us, is an anthropocentric phenomenon.
There are many who hold the view that the world of observation is merely human conception in spite of the fact that it must extinguish itself if it is correctly understood. It is repeated again and again in the course of the last decades in many variations. Ernst Laas (1837–1885) forcefully defended the point of view that only positive facts of perception should be wrought into knowledge. Alois Riehl (1849–1924), proceeding from the same fundamental view, declares that there could be no general world conception at all, and that everything that goes beyond the various special sciences should only be a critique of knowledge. Knowledge is obtained only in the special sciences; philosophy has the task of showing how this knowledge comes about and of taking care that thought should not add any element that can not be justified by the facts. Richard Wahle in his book, The Whole of Philosophy and Its End (1894), eliminates with utmost scrutiny everything that the mind has added to the “occurrences” of the world until finally the mind stands in the ocean of occurrences that stream by, seeing itself in this ocean as one such occurrence, nowhere finding a point capable of providing a meaningful enlightenment concerning them. This mind would have to exert its own energy to produce order in the occurrences. But then it would be the mind itself that had introduced that order into nature. If the mind makes a statement about the essence of the occurrences, it derives this not from the things but from itself. This it could only do if it admitted that in its own activity something essential could go on. The assumption would have to be made that the mind's judgment could have significance also for things. But in its own judgment this confidence is something that, according to Wahle's world conception, the mind is not entitled to have. It must stand idly by and watch what flows past, around and inside itself, and it would only contribute to its own deception if it were to put any credence in a conception that it formed itself about the occurrences.
What final answer could a mind find that looked into the world structure, tossing about within itself problems concerning the nature and purpose of events? As it seemed to occupy a firm stand in opposition to the surrounding world, it has had to experience that it dissolved into a flight of occurrences and flowed together with other occurrences. The mind did no longer “know” the world. It had to admit: I am not certain that there are “knowers,” but there are simply occurrences. They do, to be sure, make their appearance in a manner that the concept of knowledge could emerge prematurely and without justification. . . . and “concepts” emerged and flitted by to bring light into the occurrences, but they were will-o'-the-wisps, specters of wishful thinking, miserable postulates whose evidence meant nothing, empty forms of knowledge. Unknown factors must rule the change. Darkness was spread over nature, occurrences are the veil of the true . . . (The Whole of Philosophy and Its End ).
Wahle closes his book, which is to represent the “gifts” of philosophy to the individual sciences, theology, physiology, esthetics and civic education, with these words, “May the age begin when people will say: once was philosophy.”
In the above mentioned book by Wahle, as well as in his other books, Historical Survey of the Development of Philosophy (1895) and On the Mechanism of the Mental Life (1906), we have one of the most significant symptoms of the evolution of world conception in the nineteenth century. The lack of confidence with respect to knowledge begins with Kant and leads, finally, as it appears in Wahle, to a complete disbelief in any philosophical world conception.