Part 4 (1/2)
As the strength of Samson lay in his unshorn hair, so the strength of the mechanical theory lay, and still lies, in the acceptance of Locke's theory of human knowledge, i.e. that it is all derived from the senses.
And the Delilah who can shear away Locke's conclusions, leaves Samson helpless; mechanical materialism becomes a discredited theory. Hence the truth of the saying that the problem of knowledge is the preliminary question for philosophy.
WEAKNESS OF SPECULATIVE PHILOSOPHY.--Spinoza and Leibniz may be said to have dispensed with this foundation. Taking the scientific knowledge of their time for granted, they drew certain conclusions therefrom; but their results, however imposing, were felt to be the result rather of speculation than of reason. Such was the more or less unexpressed estimate of their work. It was undervalued, for both Spinoza and Leibniz were thinkers of the first calibre; and yet there was some justice in the charge. By the end of the eighteenth century the days of merely speculative philosophy were past.
THE CRITICAL PHILOSOPHY.--The time was ripe for a new metaphysic--for a fresh step forward in philosophic method. That step was taken by the celebrated Immanuel Kant, who is the originator of what is known, in the history of thought, as the Critical Philosophy.
The word _critical_ signifies a particular method of approaching the problem of existence, a method which must be contrasted with that of the _speculative_ philosophy, of which Spinoza and Leibniz are examples.
The critical philosophy, before attempting (as Spinoza had done) to tackle the problem of _existence_, first attacked the problem of _knowledge_. Before asking _What is the truth?_ it put the preliminary question, _What are the means at man's disposal for reaching the truth?_ It prefaced all philosophical enquiry by an examination into the nature and scope of human thought. Such was the preparatory investigation which was to place metaphysics upon a secure and scientific foundation. For the new philosophy, the gateway to all sound knowledge is the reflection of the human mind upon itself. ”Know thyself,” is its advice to the inquiring spirit of man. Here, if anywhere, is to be found the philosopher's stone.
IMMANUEL KANT.--The celebrated Immanuel Kant was born at Konigsberg in 1724, and died in his native town in 1804. Between those dates he lived the industrious and uneventful life of a university professor. The Seven Years' War and the French Revolution left him undisturbed, though not unmoved. He was a man of quiet, regular habits, and his fellow-townsmen would set their clocks by his daily promenade.[23] But the adventurous originality of his thought serves as a contrast to this peaceful picture.
Kant, indeed, laid the foundations of philosophy afresh. With characteristic insight, he went to the very root problem of all, and challenged human thought itself. Before we can know anything, we must first of all demand the credentials of the instrument by which knowledge is gained. Before asking, _What_ do I know? the preliminary question should be, _How_ do I know? Otherwise we cannot say whether we are in a position to give any answer to those ultimate problems, the answers to which const.i.tute philosophy.
It is far from easy to present Kant's criticism of knowledge at once simply and accurately. This philosopher has a not undeserved reputation for obscurity, and had he written in any other language than German, he would perhaps have found no readers.
THE PROBLEM OF KNOWLEDGE.--It had already been realised by the predecessors of Kant that what is called ”sense-experience” is a less simple process than it seems, and that our senses cannot be said to reveal to us any object as it actually _is_. John Locke himself was not the first to point out that the so-called ”secondary qualities” of any material object (i.e. colour, taste, etc.) are produced just as much by the person who perceives, as by the object which is perceived. Galileo, Descartes, and Hobbes, besides others, had been aware of this fact, which indeed becomes evident to the most superficial a.n.a.lysis of sense-experience.
The ”primary qualities,” i.e. density, extension, etc., continued to be regarded as subsisting _in_ the objects themselves, and independently of any perceiving consciousness. But even this view did not prove permanent, and it was the episcopal philosopher, George Berkeley (1685-1753) who demonstrated in his _New Theory of Vision_ that not even _these_ qualities could rightly be regarded as subsisting independently.
Thus it had already been realised, long before Kant wrote his _Critique of Pure Reason_ (published, 1781), that our senses are far from revealing to us things as they _are_; it is only the _appearances_ of things and not the _things themselves_ that the senses present to us.
Indeed, as is well known, the Scotch philosopher David Hume (1711-1776), who was a master in the art of raising problems, extended this line of criticism until it reached to pure scepticism. He put the question, If all our knowledge is derived from sense-experience, and _if_ sense-experience only supplies us with appearance and not reality, what degree of trustworthiness can there be in human knowledge? And he was not afraid to give the logical answer--None. Hume may thus be said to have brought things to an impa.s.se. As a matter of fact, what he had done was to refute Locke's theory of knowledge (i.e. that it is derived entirely from sense-experience) by means of a _reductio ad absurdum_.
THE KANTIAN CRITICISM.--Kant says that it was Hume who ”awoke him from his dogmatic slumbers.” By this he meant that Hume made him realise that it was no use indulging in philosophic speculation generally, or listening to the speculations of others, until ”the Problem of Knowledge” was satisfactorily solved. To this problem Kant applied himself. And recognising Locke to be the _fons et origo malorum_, he subjected his theory of human knowledge to a close a.n.a.lysis, and exposed it as being fallacious.
Far from sense-experience being responsible for all our knowledge, Kant proved that important elements of knowledge are quite independent of sense-experience; especially was this so in the case of certain mathematical propositions. (Hence the question, How is pure mathematics possible? was put by Kant at the beginning of his philosophy.)
But it is neither necessary nor desirable to enter into the arguments by means of which Kant proved his thesis, which was that the human mind contains in itself certain principles of knowledge (e.g. the idea of cause and effect, the ideas of mathematics, and so on) which it does not owe to sense-experience.
KANT'S COPERNICAN HYPOTHESIS.--Kant called these principles of knowledge, _forms of thought_ or _categories_. The name, perhaps, is irrelevant to our purpose; all that we need to understand is that Kant turned the tables upon Locke. Locke said that the mind was a _tabula rasa_ which pa.s.sively received impressions from outside. Kant said that the mind is nothing of the kind; it is not pa.s.sive, but active; it does not ”receive” whatever is offered, it ”selects” what it wants; and _it imposes its own ”forms of thought” upon the outside world_.
Photography had not been invented at the time of this controversy, but Kant might have said: The mind is not a photographic plate receiving impressions from without, it rather resembles the lens which impressions must pa.s.s through, and be transformed by, before they can create a picture.
Kant had, in fact, by this theory, inst.i.tuted a revolution. His new dogma was: _The mind is the mould into which all our knowledge must be cast; and the const.i.tution of our mind predetermines the shape that our knowledge takes._
Thus Kant had discovered that not only sensuous perception, but rational understanding also, has its forms and presuppositions. Just as we become aware of objects only by means of senses which perhaps hide or distort as much as they reveal; so also our rational knowledge is conditioned by the nature of our understanding, which dictates to reality the ”forms”
under which it can be understood and known.
MECHANISM UNDERMINED.--How did this affect the mechanical theory? The connection is obvious. Mechanism is nothing but one of the forms of thought that the mind imposes on phenomena. Just as Copernicus had discovered that it is due to our position on the earth that the heavenly bodies _appear_ to move round us, so Kant had discovered that it is due to the nature of our senses and understanding that we perceive things in s.p.a.ce and time, and understand them as being mechanically determined.
The s.p.a.ce and time, and the mechanical determinism are not in the things, _but in our minds_. The fact is that we can only grasp things under these forms. s.p.a.ce, time, mechanical causation are forms and laws, _not_ of nature, _but of the human intellect_, which is so const.i.tuted as to see things in this way.
Thus those axioms of science and of mathematics which lie at the base of all exact knowledge, and which had hitherto been regarded as _objective_, i.e. as inherent in the nature of things, were shewn by Kant to be, as a matter of fact, _subjective_, that is (in Kant's own phrase) ”they express the conditions under which alone we are able to apprehend or understand the object.” Thus all knowledge is conditioned by our nature, by the framework, so to speak, not only of our senses but of our minds.
In this way the mechanical view was outflanked; that view certainly seems to us inevitable and certain, but this is due to the const.i.tution of our minds; the world seems to us to be determined, just as it seems blue to a person wearing blue spectacles. But there is no sufficient reason for supposing that it _is_ either determined or blue. The law of mechanical causation is an axiom, but it is a subjective axiom.
APPEARANCE AND REALITY.--This may not seem much of an advance on Hume's position. Human knowledge still seems precarious, if we a.s.sume the mind to be a kind of dictator which imposes its own laws upon nature. And Kant indeed frankly admitted that neither our senses nor our reason were able to reveal to us things as they _are_, but only things as they _seem_; we grasp _appearance_, not _reality_, and (to use Kant's phraseology) _phenomena_ not _noumena_. Thus Kant cut away the ground from under all rationalistic _dogmatism_; he shewed its presumptuous futility.
THE PATHWAY TO REALITY.--Kant, however, did not remain satisfied with the negative results of his critical philosophy, valuable as these were.