In his criticism of Kant’s system, Herbert Spencer drew a picture of a world inhabited by men who had no sympathy for their fellows and who did good to them against their natural instincts and only from a pure sense of duty. Spencer thought that such a world would be uninhabitable. Clearly, moral conduct, on the Kantian basis, could be followed only by exceptional persons, for most men follow their inclinations rather than any sense of duty. People of lower culture would accept kindnesses from others without caring whether the motive were kindness or a sense of duty, but highly civilised people would not endure service from those whom they knew to be acting against their instincts in obedience to a sense of duty. And so men would be driven to hide the real motives of their conduct, lest they should offend the sensibility of those towards whom their moral conduct was directed. Such cases, where the real motive is concealed, show how impossible it is to judge of conduct from the motives which may be supposed to have inspired it. As it is generally impossible to know whether some altruistic conduct has been inspired by kindness or has been performed as a duty, it is better to give up any attempt to appraise the springs of moral conduct.

Kant himself realised the need of some other standard for appraising human conduct. With such a purpose he arrived at his well-known maxim:—“Let your conduct be such that your motive might serve as a standard of universal application.” To explain the maxim he gave a number of examples. A man who is without money and cannot pay a debt is in doubt as to whether he should promise to repay his creditor. According to Kant, he ought to ask himself what would be the result if such a promise were to be made under similar circumstances by everyone. It is plain that if such false promises became universal, they would cease to be believed and so would be impracticable in actual life. Kant’s formula, therefore, would supply a rational basis for the discrimination of immoral conduct. In the case of theft it would operate as follows: if it became the custom for everyone to take whatever he wanted, private property and theft would simultaneously cease to exist. So also suicide is immoral, since if it became general the human race would cease to exist.

Kant, however, was looking at only one side of the problem. Moral conduct is frequently limited to an individual, and cannot be generalised for all humanity. Thus, for instance, if one about to sacrifice his life for the good of his fellows were to estimate his action according to Kant’s formula, he would reach a conclusion similar to that in the case of suicide; if everyone were to sacrifice his life for others, no one would remain alive, and so, according to Kant, the sacrifice of one’s life for the good of others would be an immoral act.

It is plain that in his search for a rational basis of morality, Kant found only a hollow form, void of any substantial body of morality. It is not enough that a moral man should take his consciousness of duty as a guide. He must know what would be the result of his acts. If it is immoral to make a false promise, it is because people would lose confidence in such promises, and confidence is necessary to our well-being. When the formula of Kant condemns theft, it is because, if theft became general, there could be no private property, and property is regarded as necessary to the well-being of men. Suicide is immoral, according to Kant, because it would lead to the disappearance of the human race, and human life is of course a good.

Kant tried to found his theory of morality on a rational basis which excluded the idea of the general good, but it was impossible for him to avoid it. His “practical reason,” when it raised the consciousness of duty to a principle, should have pointed the goal towards which moral acts were to be directed. In this matter, I find that Kant’s ideas are very vague, although extremely interesting.

The innate feeling of duty implies the will to pursue moral conduct. This will is independent of the circum-ambient conditions. Kant in his nebulous language explains this consideration as follows:—“Our reason informs us of a law to which all our maxims are subject, as if our will had created its own natural order of things. This law, then, is in the sphere of a nature which we do not know empirically but which the freedom of the will makes possible, a nature which is supra-sensible, but which from the practical point of view we make objective, because it is created by our will in virtue of our existence as rational beings. The difference between the laws of a nature to which the will is subject and a nature subject to the will subsists in this, that in the first the objects must be the causes which determine the will, whilst in the second, the will itself causes the objects so that the causality of the will resides exclusively in pure reason, pure reason being thus practical reason” (Critique of Practical Reason).

So far as I can follow the argument of Kant, it seems to me to imply that rational morality cannot be bound by human nature as it exists. I may perhaps interpret Kant’s thought as if he had the intuition that the moral will was capable of modifying nature by subjecting it to its own laws.

On the other hand, several critics of Kant have attempted to improve his theory of morality by reconciling it with human nature as it actually exists. Vacherot,[228] for instance, has taken such an attitude in the most definite fashion. He insists that Kant “did not appreciate the capital importance of the object of the moral law. The problem which under the designation summum bonum absorbed the schools of antiquity plays a minor part in the Kantian theory. Kant should have recognised that human destiny is not limited to duty but must include happiness” (p. 316).

But what is this “happiness” which is to be the standard of human actions? To answer this Vacherot places himself in the position of those ancient philosophers whom I discussed in The Nature of Man. He makes his point absolutely clear. “What is the ‘good’ for any being? The attaining of its purpose. What is the purpose of a being? The simple development of its nature. Apply this to man and morality. When human nature is known by observation and analysis, the deduction can be made as to what is the purpose, and the good, and therefore the law of man. For the conception of the good necessarily involves the idea of duty and of law to be imposed on the will. We have to fall back, then, on knowledge of man, but it must be complete knowledge, a recognition of the faculties, feelings, and inclinations that are peculiar to him and that distinguish him from animals” (p. 319). Here is a summary of this doctrine:—“Develop all our natural powers, subordinating those which are subsidiary to those which form the peculiar quality of human beings; this is the true economy of the little world we call human life; this is its purpose and this its law. The formula states in the most scientific and least doubtful form a very old truth, the foundation of all morality and the test of all its applications. If we seek to know what are justice, duty and virtue, we must look in the world itself, and not above or below it” (Op. 301).