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Kant (A History of Western Philosophy)

Before discussing Kant’s philosophy, Russell gives an overview of 18th century philosophy. British empiricists like Hume and Berkeley dominated philosophy in that century. But there was a conflict in these men, between their temper of mind and the tendency of their doctrines. They were socially minded, urbane and friendly.

But their theoretical philosophy led to subjectivism. This tendency was found in St Augustine and in Descartes’s cogito. The culmination was with Leibniz’s monads. Leibniz believe that his experience would not change, even if the rest of the world were annihilated, but he devoted himself to the reunion of Catholicism and Protestantism. A similar inconsistency exists in Locke, Berkeley, and Hume.

Lock’s inconsistency was in the theory.

GERMAN IDEALISM IN GENERAL

We saw in an earlier chapter that Locke says, on the one hand: ‘Since the mind, in all its thoughts and reasonings, hath no other immediate object but its own ideas, which it alone does or can contemplate, it is evident that our knowledge is only conversant about them.’ And: ‘Knowledge is the perception of the agreement or disagreement of two ideas.’

Bertrand Russell, A History of Western Philosophy

Yet he maintains that we three kinds of knowledge of real existence: intuitive, of our own, demonstrative, of God’s, and sensitive, things present to sense. Simple ideas are the product of thing that operate on the mind in a natural way. But he does not explain how he does this – and it goes beyond ‘the agreement or disagreement of two ideas’.

Berkeley nearly ended this consistency when he admitted that only minds and ideas existed, and not the external world. But had he been completely consistent, he would have denied knowledge of God and of all minds but his own. Yet such a denial was in conflict with his feelings as a clergyman and as a social being.

Hume did everything in the name of theoretical consistence, but did not try to conform his practice to theory. Hume denied the Self, and threw doubt on induction and causation. He accepted Berkeley’s abolition of matter, but not Berkeley’s substitute (God’s ideas). While he, like Locke, did not admit a simple idea without an antecedent impressions, he imagined an ‘impression’ as a state of mind directly caused by something external to the mind.

But he could not admit this as a definition of ‘impression’ since he questioned the notion of ’cause’. On his view, an ‘impression’ would have to be defined by some intrinsic character distinguishing it from an ‘idea’, since it could not be defined causally. He could not therefore argue that impressions give knowledge of things external to ourselves, as had been done by Locke, and by Berkeley. He should, therefore, have believed himself shut up in a solipsistic world, and ignorant of everything except his own mental states and their relations.

Bertrand Russell, A History of Western Philosophy

Hume, by being consistent, showed that if empiricism was carried to its logical conclusion, it would lead to results few people would accept. Locke knew this, and he said, when he spoke from the perspective of his own critic:

‘If knowledge consists in agreement of ideas, the enthusiast and the sober man are on a level.’ Locke, living at a time when men had grown tired of ‘enthusiasm’, found no difficulty in persuading men of the validity of his reply to this criticism

Bertrand Russell, A History of Western Philosophy

Rousseau came at a moment when people were getting tired of reason, revived ‘enthusiasm’, and, accepted the bankruptcy of reason, he allowed the heart to decide questions which the head felt doubtful of.

From 1750 to 1794, the heart spoke louder and louder. Under Napoleon, heart and head were alike silenced. In Germany, the reaction against Hume’s agnosticism took a form far more profound and subtle than that which Rousseau had given to it. Kant, Fichte, and Hegel developed a new kind of philosophy, intended to safeguard both knowledge and virtue from the subversive doctrines of the late eighteenth century.

Bertrand Russell, A History of Western Philosophy

In Kant and even more in Fichte, the subjectivist tendency that begins with Descartes was carried to new extremes. With regards to subjectivism, the reaction to Descartes started with Hegel, who tried with logic, to establish a new way of escape from the individual into the world. German idealism has affinities with the romantic movement. These are clear in Fichte, and more so in Schelling, and partly so in Hegel.

Kant, the founder of German idealism is not politically important but wrote interesting essays on political subjects. Both Fichte and Hegel set forth political doctrines that had and still have a profound impact on the course of history. Neither can be understood without studying Kant.

Something to know about the German idealists. The critique of knowledge as a way of reaching philosophical conclusions is emphasized by Kant and accepted by his followers. The emphasis is on the mind rather than matter, which leads to the assertion that only the mind exists. There is a vehement rejection of utilitarianism in favor of systems argued for by abstract arguments.

There is a scholastic tone that did not exist in the earlier French and English philosophers: Kant, Fichte and Hegel were philosophy professors. They addressed an educated audience, not gentlemen of leisure speaking to amateurs. Though their effects were revolutionary, they were not intentionally subversive. Both Fichte and Hegel were defenders of the State and they led exemplary and academic lives. They had orthodox views on moral subjects. They innovated in theology but did so in the interests of religion.

Kant’s most important book is The Critique of Pure Reason (first edition, 1781; second edition, 1787). The purpose of this work is to prove that, although none of our knowledge can transcend experience, it is, nevertheless, in part a priori and not inferred inductively from experience.

Bertrand Russell, A History of Western Philosophy

Our a priori knowledge includes logic sand whatever is not included in logic or deduced from it. He makes two distinctions which are confounded in Leibniz: analytic and synthetic propositions, a priori and empirical propositions.

An analytic proposition is when the predicate is part of the subject. ‘a tall man is a man’. These propositions follow from the law of contradiction. To say that a tall man is not a man is self-contradictory. A synthetic proposition is one that is not analytic. What we know only through experience is synthetic. We cannot discover truths like ‘Napoleon was a great general’ through the analysis of concepts.

But Kant, unlike Leibniz and all previous philosophers, will not admit the converse – that all synthetic propositions can only be known through experience. This brings us to the second distinction. An empirical proposition is one we cannot know except by the help of sense perception, either our own senses or someone else’s testimony. These include the facts of history and geography and laws of science.

Our knowledge depends on data from observation. An ‘a priori’ proposition is one which may be elicited through experience, but when known, is seen to have a basis other than experience. A child learning arithmetic may profit from seeing two marbles and two other marbles, and realize he is seeing four marbles. But when he grasps the general proposition ‘two and two are four’ he does not need further confirmation by examples – the proposition has a certainty that induction is lacking. If I give you an a synthetic proposition (Napoleon was a great general), you would not be able to deduce much else from it, unlike mathematics. All mathematical propositions are a priori.


Hume had proved that the law of causality is not analytic and had inferred that we could not be certain of its truth. Kant accepted the view that it is synthetic, but nevertheless maintained that it is known a priori. He maintained that arithmetic and geometry are synthetic but are likewise a priori. He was thus led to formulate his problem in these terms: How are synthetic judgments a priori possible? The answer to this question, with its consequences, constitutes the main theme of The Critique of Pure Reason.

Bertrand Russell, A History of Western Philosophy

Kant’s solution to this problem came after 12 years of thinking about it. It took him two months to write down the solution.

In the preface to the first edition he says: ‘I venture to assert that there is not a single metaphysical problem which has not been solved, or for the solution of which the key at least has not been supplied.’ In the preface to the second edition he compares himself to Copernicus and says that he has effected a Copernican revolution in philosophy.

Bertrand Russell, A History of Western Philosophy

Kant said that external causes only the matter of sensation, but our minds order this matter in space and time and imbues us with the concepts needed to understand experience. Things in themselves, which are causes of sensations, are not knowable, they are not in space or time, they ae not substances, and cannot be described by other concepts Kant called ‘categories.’ Space and time are subjective and are part of our apparatus of perception.

But this means that we can be sure that whatever we experience will exhibit the characteristics dealt with by geometry and the science of time. Russel gives an example: If you always wore blue spectacles, you will always see things in blue. And since you wear spatial spectacles in your mind, you will always see things in space. Geometry is a priori in that sense that it must be true of everything experienced, but we have no reason to think that anything similar is true of things in themselves, which we do not experience.


Space and time, Kant says, are not concepts; they are forms of ‘intuition’. There are also, however, a priori concepts; these are the twelve ‘categories’, which Kant derives from the forms of the syllogism. The twelve categories are divided into four sets of three: (1) of quantity: unity, plurality, totality; (2) of quality: reality, negation, limitation; (3) of relation: substance-and-accident, cause-and-effect, reciprocity; (4) of modality: possibility, existence, necessity. These are subjective in the same sense in which space and time are—that is to say, our mental constitution is such that they are applicable to whatever we experience, but there is no reason to suppose them applicable to things in themselves.

Bertrand Russell, A History of Western Philosophy

With regards to cause, there is an inconsistency, for things as themselves are causes of sensations, and free will are causes of events in space and time. But this inconsistency is not accidental, it is an essential part of his system.

Kant spends a lot of time showing what fallacies arise from applying space and time or the categories to things that are not experienced. When this is done, we are troubled by ‘antinomies’ – mutually contradictory propositions each of which can apparently be proved.

Kant gives four such antinomies, each consisting of thesis and antithesis. In the first, the thesis says: ‘The world has a beginning in time, and is also limited as regards space.’ The antithesis says: ‘The world has no beginning in time, and no limits in space; it is infinite as regards both time and space.’ The second antinomy proves that every composite substance both is, and is not, made up of simple parts. The thesis of the third antinomy maintains that there are two kinds of causality, one according to the laws of nature, the other that of freedom; the antithesis maintains that there is only causality according to the laws of nature. The fourth antinomy proves that there is, and is not, an absolutely necessary Being.

Bertrand Russell, A History of Western Philosophy

Hegel was greatly influenced by this part of the Critique. Hegel’s dialectic proceeds through antinomies. In a famous section, Kant demolishes all the purely intellectual proofs of the existence of God. He makes clear that he other reasons for believing in God, he mentions these in The Critique of Practical Reason. But for now, his purpose is purely negative.

He says there are only three proofs of God’s existence by pure reason. The ontological proof, the cosmological proof, and the physicotheological proof.

The ontological proof, as he sets it forth, defines God as the most real being; i.e. the subject of all predicates that belong to being absolutely. It is contended, by those who believe the proof valid, that, since ‘existence’ is such a predicate, this subject must have the predicate ‘existence’, i.e. must exist. Kant objects that existence is not a predicate. A hundred thalers that I merely imagine may, he says, have all the same predicates as a hundred real thalers.

Bertrand Russell, A History of Western Philosophy

There is nothing about existence that says something meaningful enough about its subject thus it cannot be a predicate.

The cosmological proof says: If anything exists, then an absolutely necessary Being must exist; now I know that I exist; therefore an absolutely necessary Being exists, and this must be the most real being.

Bertrand Russell, A History of Western Philosophy

Kant says that the last step in this argument is the ontological argument over again, it is refuted by what has been already said.

The physico-theological proof is the familiar argument from design, but in a metaphysical dress. It maintains that the universe exhibits an order which is evidence of purpose. This argument is treated by Kant with respect, but he points out that, at best, it proves only an Architect, not a Creator, and therefore cannot give an adequate conception of God. He concludes that ‘the only theology of reason which is possible is that which is based upon moral laws or seeks guidance from them’.

Kant maintains that God, freedom, and immortality are the three ‘ideas of reason.’ While pure reason leads us to form these ideas, it cannot itself prove their reality. These ideas are important because they are practical, they relate to morals. The use of reason for purely intellectual properties leads to fallacies. There is only one proper use for reason, and it is for moral purposes.

The practical use of reason is developed briefly near the end of The Critique of Pure Reason, and more fully in The Critique of Practical Reason (1786). The argument is that the moral law demands justice, i.e. happiness proportional to virtue. Only Providence can insure this and has evidently not insured it in this life. Therefore, there is a God and a future life; and there must be freedom, since otherwise there would be no such thing as virtue.

Bertrand Russell, A History of Western Philosophy


Kant’s ethical system, as set forth in his Metaphysic of Morals (1785), has considerable historical importance. This book contains the ‘categorical imperative’, which is a familiar phrase. As might be expected, Kant will have nothing to do with utilitarianism, or with any doctrine which gives to morality a purpose outside itself. He wants, he says, ‘a completely isolated metaphysic of morals, which is not mixed with any theology or physics.

All moral concepts have their seat and origin wholly a priori in the reason. Moral worth exists only when a man acts from a sense of duty; it is not enough that the act should be such as duty might have prescribed. The tradesman who is honest from self-interest, or the man who is kind from benevolent impulse, is not virtuous.

Bertrand Russell, A History of Western Philosophy

Morality is derived from the concept of law; for, though everything in nature acts according to laws, only a rational being has can act according to the idea of law; i.e. by Will. The idea of an objective principle in so far as it is compelling to the will, is called a command of the reason, and the formula of the command is called an imperative.

There are two imperatives: the hypothetical imperative which says ‘You must do so-andso if you wish to achieve such-and-such an end’; and the categorical imperative, which says that a certain kind of action is objectively necessary, without regard to any end. The categorical imperative is synthetic and a priori. Its character is deduced by Kant from the concept of Law: ‘If I think of a categorical imperative, I know at once what it contains. For as the imperative contains, besides the Law, only the necessity of the maxim to be in accordance with this law, but the Law contains no condition by which it is limited, nothing remains over but the generality of a law in general, to which the maxim of the action is to be conformable, and which conforming alone presents the imperative as necessary. Therefore, the categorical imperative is a single one, and in fact this: Act only according to a maxim by which you can at the same time will that it shall become a general law.’ Or: ‘Act as if the maxim of your action were to become through your will a general natural law.

Bertrand Russell, A History of Western Philosophy

It is wrong to borrow money, according to the categorical imperative, because if everyone borrowed, there would be no money left to borrow. Theft and murder are wrong for the same reason.

But some acts that are wrong cannot be shown to be wrong through this law such as suicide. A melancholic could wish that everyone commit suicide. His maxim provides a necessary but not a sufficient criterion of virtue. A sufficient criterion is possible only if we abandon Kant’s formal view and consider the effects of actions.

But Kant insists that virtue is independent of the results of an action. Virtue only depends on the principle of which it is itself a result. If this is accepted, there cannot be anything more concrete than his maxim.

Kant maintains, although his principle does not seem to entail this consequence, that we ought so to act as to treat every man as an end in himself. This may be regarded as an abstract form of the doctrine of the rights of man, and it is open to the same objections. If taken seriously, it would make it impossible to reach a decision whenever two people’s interests conflict.

Bertrand Russell, A History of Western Philosophy

The difficulties become obvious in political philosophy, which requires some principle, like the will of the majority, by which some interests can be sacrificed to those of others.

An ethic of government is only possible if the end of government is the same, and the only end compatible with justice is the good of the community. But we can interpret Kant’s principle, not as meaning that each man is an absolute end, but that all men should count equally in determining actions that affect many people. This principles can be seen as giving an ethical basis for democracy. In this interpretation, it does run into the problem Russell pointed out.

"Silence is the best expression of scorn" - G.B. Shaw

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