The Philosophy of Immanuel Kant

by A. D. Lindsay

THE IDEA OF CRITICISM

"It is a difficult matter," says Heine, "to write the life history of Immanuel Kant, for he had neither life nor history. He lived a mechanically ordered, abstract, old bachelor kind of existence in a quiet, retired alley in Königsberg, an old town in the north-east corner of Germany." The times he lived in were stirring enough. He was born in 1724, and died in 1804. He lived through the Seven Years' War that first made Germany a nation, he followed with sympathy the United States War of Independence, he saw the French Revolution and the beginning of the career of Napoleon. Yet in all his long life he never moved out of the province in which he was born, and nothing was allowed to interrupt the steady course of his lecturing, studying, and writing. "Getting up," continues Heine, "drinking coffee, lecturing, eating, going for a walk, everything had its fixed time; and the neighbours knew that it must be exactly half-past four when Immanuel Kant, in his gray frock-coat, with his Spanish cane in his hand, stepped from his door and walked towards the little lime-tree avenue, which is called after him the Philosopher's Walk." "Strange contrast," reflects Heine, "between the man's outward life and his destructive, world-smashing thoughts." As the political history of the eighteenth century came to an end when the French Revolution spilled over the borders of France and drove Napoleon up and down Europe, breaking up the old political systems and inaugurating modern Europe, so its opposing currents of thought were gathered together in the mind of a weak-chested, half-invalid little man in Königsberg, and from their meeting a new era in philosophy began.

There are some philosophers to whom truth seems to come almost unsought, as an immediate authoritative vision. Kant was not one of these. His greatest work, the Critique of Pure Reason, was conceived when he was forty-eight, and published in 1781, when he was fifty-seven. It was the outcome of half a lifetime's patient study and thought. Heine says of him: "He was the perfect type of the small shopkeeper. Nature had meant him to weigh coffee and sugar, but fate willed that he should weigh other things and put a God on his scales, and his weighing was exact." The sneer is unjust, but there is something in the simile; for Kant's philosophy was a kind of taking stock, a survey of the great movement of thought from the time when the Renaissance and the Reformation made thought free, an attempt to estimate the achievements of the new sciences, to deal with their conflicting claims and ideals and say what it all came to. In Kant modern science, which began with Descartes and Galileo, first became conscious of itself.

This taking stock Kant called Criticism. His great books are all called Critiques--the Critique of Pure Reason, the Critique of Practical Reason, the Critique of Judgment. He called his philosophy the Critical Philosophy or Critical Idealism. Essential to an understanding of Kant is an understanding of what he meant by criticism, and why he opposes it to dogmatism and scepticism; for the necessity and possibility of such a criticism was his great philosophical discovery. We have called Kant's work a survey of the achievements of the thought of his times, but it was very much more than that, and has a much more universal significance than could belong to any history of the thought of one epoch. For these achievements of thought, though great, were conflicting and partial. They contrasted with failure and barrenness in other directions, and they seemed to be due to different methods. This success of thought in one direction and its failure in another, and this uncertainty about the true method of science, were problems which at once presented themselves to an impartial observer, and Kant held that they could be answered only by taking stock of actual attainments, and by criticism of the powers and range of human thought in general.

The problem that presented itself to him will be understood if we look for a moment at the history of thought in the seventeenth and eighteenth centuries. One thing that Kant noted in it was the steady and sure progress of physics. "With the experiments of Galileo and Torricelli," he says in the preface to the second edition of the first Critique, "a new light flashed on all students of nature." The continued success of physics meant the successful application of mathematics to the concrete world, and along with it a remarkable development of mathematics itself. This sudden success inspired men to feel that they had discovered a way of explaining the universe; they contrasted the fertility of their new methods with the barrenness of scholastic speculation in morals and theology; they felt confident that all that was wanted to the attainment of certain knowledge in all spheres of human interest was the extension of these methods. If men would only set to work the right way, they were sure that all difficulties would be overcome; and, by reflection upon their own success, they hoped to explain what the right way was.

Unfortunately this was not easy, for the advance from pure mathematics to physics, from a study of the nature of pure mathematical conceptions to an inquiry into the laws of falling bodies, implied a change whose nature was not clear to the men who had themselves made the advance. A conflict arose between those who thought more of the fact that knowledge, to be certain, must be capable of mathematical expression, and those who thought more of the basis of experiment and observation on which the new sciences depended, who remembered that these sciences began when Galileo, instead of thinking in the abstract how bodies ought to fall, dropped bodies of different weights from the top of the leaning tower of Pisa and observed what actually happened. Descartes was the great representative of the first school. He began by insisting on the difference between mathematical truth which could be, as he said, clearly and distinctly conceived, and ordinary opinion about things which was full of guesswork and imagination. Scientific knowledge was possible, he thought, only by apprehending the real or primary qualities of things which were mathematical, in contradistinction to their secondary qualities--their colour, smell, &c.--which were less real. Thence he came to think that the real world was mathematical in nature, like a huge, intricate geometrical figure. The elements of mere fact, in our present knowledge, its dependence on observation and experiment, he thought of as temporary defects which the progress of science would remove. What we ordinarily call perception, indeed, in the sense of awareness of things in time and space, was described by Descartes' successors as confused thinking. Our knowledge of the world would, it was hoped, become a vast mathematical system, all the detail and complexity of which would be rigorously deducible from a few central truths.

This general way of thinking was called Rationalism. Kant ordinarily calls it Dogmatism. It was attacked by other scientists for its view of the nature of space and time. No one who reflects at all can fail to distinguish a difference between the way in which we see the truth of a geometrical proposition--that, e.g., the three angles of a triangle are equal to two right angles--and the way in which we judge that such and such a figure drawn on a board is a triangle, or make judgments about the way in which things are actually arranged in space or succeed in time. Judgments of the latter kind involve words like "here" and "there," "now" and "then," words which are all a kind of pointing. It seems impossible from considering the nature of a triangle to deduce why any existing thing should be called triangular, and all statements about the position of things in space and time seem to be derived not from a consideration of the general nature of space and time, but from observation. Now the science which had made perhaps the most striking progress in the time we are speaking of, physical astronomy, involved any number of statements about the position of bodies in space. The Rationalist school admitted this, but held that that was due to the fact that science was not sufficiently thought out. In time, they hoped, all statements about position in space would disappear. To think of things in spatial order was to think confusedly. Newton, on the other hand, held that space could not be explained away, that astronomy implied an absolute space in which things existed, that the spatial relations of things could not be explained by the nature of the things themselves, but only by a reference to absolute space in which they all were. This meant that observation or perception was something of which you could not hope and should not wish to get rid, and that an ideal of knowledge in which all applied mathematics should have been transmuted into pure mathematics was a vain one. Astronomy implied both mere observation and apprehension of necessary relations. Here was a science which seemed to employ both methods together. Galileo, in fact could not have made his discovery without observation but men had observed bodies falling for ages without discovering the laws of motion. Further, the laws of motion, once discovered, made men in some degree independent of observation, made them able to say of actual concrete things not only what had happened, but what must happen.

Such difficulties as these arose from reflection on the aims and methods of the mathematical sciences, but there was much genuinely scientific inquiry in the seventeenth and eighteenth centuries, which showed no signs of taking mathematical form; chemistry and biology, for example, were still almost entirely empirical. Furthermore, thinkers were not concerned with science alone. These centuries saw a great revival of interest in speculation on human affairs, history, politics, morals and theology. England, which was the home of free discussion on questions of politics and morals, and where, more than in most other countries, there was free discussion on theology, became also the home of empiricism. The empirical movement, indeed, drew much of its impetus from a reaction against Hobbes, the only great English thinker who unhesitatingly applied the mechanical and deterministic assumptions of the new sciences to morals and politics, and arrived by this uncompromising method at results so obviously repellent that no man of any sense could accept them, and so consistently presented that they could not be refuted save by a refutation of the assumptions upon which they were founded. Such a refutation was, in fact, undertaken by Locke, the first great representative of the empirical school. He was interested alike in the more obviously empirical sciences of chemistry and biology, and in politics. He was not a very consistent or systematic thinker, but he had other gifts perhaps as valuable. He was a man of great common sense and breadth of view, and was able thereby to take a conspectus of the general situation in the various spheres of inquiry, to notice the obvious differences in our knowledge of mathematics, of chemical and biological fact, and of theology, and to see that these constituted a problem. We find in him the first statement of the necessity of philosophical criticism. It is contained in his account of the origin of the Essay concerning Human Understanding. "Were it fit to trouble thee with the history of this Essay, I should tell thee that five or six friends, meeting at my chamber, and discoursing on a subject very remote from this" (they were discussing the "principles of morality and revealed religion"), "found themselves quickly at a stand, by the difficulties that rose on every side. After we had awhile puzzled ourselves, without coming any nearer a resolution of those doubts which perplexed us, it came into my thoughts that we took a wrong course; and that, before we set ourselves upon inquiries of that nature, it was necessary to examine our own abilities, and see what objects our understandings were, or were not, fitted to deal with."

We have here the same general starting point of inquiry as we shall afterwards find in Kant. There are certain, obstinate puzzles which we meet with in discussion which can only be solved by going back and inquiring into the nature of knowledge and the powers of our minds. Unfortunately, as Kant points out, Locke went the wrong way about his task. He describes it as "a plain historical inquiry." He thought that he had only to look into his mind and see what was in it, as he might open a door and look into a room. The result is that he thinks of all knowledge as consisting simply in looking at what is present to the mind. We can know, therefore, whatever can be present to the mind, and the limitations of knowledge are discovered by asking what can be so present to the mind. The conclusions to which he comes as to different spheres of human inquiry are roughly these: We can have knowledge of mathematics because there we are concerned only with ideas present to the mind, and with noting their agreement and disagreement. We can have no knowledge of such questions as the immortality of the soul, or the nature of spirits, for they are beyond our observation. As regards existing things, we can have knowledge of them, in so far as they are present to our minds, and no further. The meaning of "present to the mind" was never clearly analysed by Locke; but he meant, for example, that we can observe that an object which is yellow, and which we call gold, is also heavy, and can be dissolved by Aqua Regia, but we cannot say why that is so, and we ought not, on Locke's principles, to have any ground for supposing that these qualities will go on co-existing.

The element of truth in Locke's position is this. When we are examining concrete things like pieces of gold or any chemical substance, we find in them a number of varying qualities whose connection we cannot understand. We do not know why a metal of a certain specific gravity should also be yellow; we can only note the fact. Hence in chemistry our method must be quite different from the method of mathematics. In mathematics we start from the definition, and we can understand the connection of the properties of a geometrical figure, and see that they all follow necessarily from the definition. But in sciences like chemistry a definition does not take us any further; we can only find out the properties of a substance by observation and experiment. Locke explains this difference by saying that in the former case we are only concerned with agreement among our own ideas, in the second place we are concerned somehow with things outside us. This explanation will not stand. It is not true that mathematics is simply analysis of an arbitrary definition, as Locke seems to suggest. It involves construction, or, as Kant calls it, synthesis. It is a process of discovering new truths. Secondly, our statements about concrete objects are not statements of qualities we see co-existing at the moment. They are statements about all gold or all men; in other words, they are universal, and Locke found it impossible to explain the universality of such propositions--what we mean, e.g. when we talk about the nature of gold or of man, not of this gold or this man that I see before me. Lastly, this distinction of mathematics and the empirical sciences by a distinction of spheres does not allow, as we saw, for a science like astronomy, which builds on mathematics and yet applies to the concrete world.