The period of history which is commonly called 'modern' has a mental outlook which differs from that of the medieval period in many ways. Of these, two are the most important: the diminishing authority of the Church, and the increasing authority of science. With these two, others are connected. The culture of modern times is more lay than clerical. States increasingly replace the Church as the governmental authority that controls culture. The government of nations is, at first, mainly in the hands of kings; then, as in ancient Greece, the kings are gradually replaced by democracies or tyrants. The power of the national State, and the functions that it performs, grow steadily throughout the whole period (apart from some minor fluctuations); but at most times the State has less influence on the opinions of philosophers than the Church had in the Middle Ages. The feudal aristocracy, which, north of the Alps, had been able, till the fifteenth century, to hold its own against central governments, loses first its political and then its economic importance. It is replaced by the king in alliance with rich merchants; these two share power in different proportions in different countries. There is a tendency for the rich merchants to become absorbed into the aristocracy. From the time of the American and French Revolutions onwards, democracy, in the modern sense, becomes an important political force. Socialism, as opposed to democracy based on private property, first acquires governmental power in 1917. This form of government, however, if it spreads, must obviously bring with it a new form of culture; the culture with which we shall be concerned is in the main 'liberal', that is to say, of the kind most naturally associated with commerce. To this there are important exceptions, especially in Germany; Fichte and Hegel, to take two examples, have an outlook which is totally unconnected with commerce. But such exceptions are not typical of their age.
The rejection of ecclesiastical authority, which is the negative characteristic of the modern age, begins earlier than the positive characteristic, which is the acceptance of scientific authority. In the Italian renaissance, science played a very small part; the opposition to the Church, in men's thoughts, was connected with antiquity, and looked still to the past, but to a more distant past than that of the early Church and the Middle Ages. The first serious irruption of science was the publication of the Copernican theory in 1543; but this theory did not become influential until it was taken up and improved by Kepler and Galileo in the seventeenth century. Then began the long fight between science and dogma, in which traditionalists fought a losing battle against new knowledge.
The authority of science, which is recognized by most philosophers of the modern epoch, is a very different thing from the authority of the Church, since it is intellectual, not governmental. No penalties fall upon those who reject it; no prudential arguments influence those who accept it. It prevails solely by its intrinsic appeal to reason. It is, moreover, a piecemeal and partial authority; it does not, like the body of Catholic dogma, lay down a complete system, covering human morality, human hopes, and the past and future history of the universe. It pronounces only on whatever, at the time, appears to have been scientifically ascertained, which is a small island in an ocean of nescience. There is yet another difference from ecclesiastical authority, which declares its pronouncements to be absolutely certain and eternally unalterable: the pronouncements of science are made tentatively, on a basis of probability, and are regarded as liable to modification. This produces a temper of mind very different from that of the medieval dogmatist.
So far, I have been speaking of theoretical science, which is an attempt to understand the world. Practical science, which is an attempt to change the world, has been important from the first, and has continually increased in importance, until it has almost ousted theoretical science from men's thoughts. The practical importance of science was first recognized in connection with war; Galileo and Leonardo obtained government employment by their claim to improve artillery and the art of fortification. From their time onwards, the part of men of science in war has steadily grown greater. Their part in developing machine production, and accustoming the population to the use, first of steam, then of electricity, came later, and did not begin to have important political effects until near the end of the nineteenth century. The triumph of science has been mainly due to its practical utility, and there has been an attempt to divorce this aspect from that of theory, thus making science more and more a technique, and less and less a doctrine as to the nature of the world. The penetration of this point of view to the philosophers is very recent.
Emancipation from the authority of the Church led to the growth of individualism, even to the point of anarchy. Discipline, intellectual, moral, and political, was associated in the minds of the men of the Renaissance with the scholastic philosophy and ecclesiastical government. The Aristotelian logic of the Schoolmen was narrow, but afforded a training in a certain kind of accuracy. When this school of logic became unfashionable, it was not, at first, succeeded by something better, but only by an eclectic imitation of ancient models. Until the seventeenth century, there was nothing of importance in philosophy. The moral and political anarchy of fifteenth-century Italy was appalling, and gave rise to the doctrines of Machiavelli. At the same time, the freedom from mental shackles led to an astonishing display of genius in art and literature. But such a society is unstable. The Reformation and the Counter-Reformation, combined with the subjection of Italy to Spain, put an end to both the good and the bad of the Italian Renaissance. When the movement spread north of the Alps, it had not the same anarchic character.
Modern philosophy, however, has retained, for the most part, an individualistic and subjective tendency. This is very marked in Descartes, who builds up all knowledge from the certainty of his own existence, and accepts clearness and distinctness (both subjective) as criteria of truth. It is not prominent in Spinoza, but reappears in Leibniz's windowless monads. Locke, whose temperament is thoroughly objective, is forced reluctantly into the subjective doctrine that knowledge is of the agreement or disagreement of ideas—a view so repulsive to him that he escapes from it by violent inconsistencies. Berkeley, after abolishing matter, is only saved from complete subjectivism by a use of God which most subsequent philosophers have regarded as illegitimate. In Hume, the empiricist philosophy culminated in a scepticism which none could refute and none could accept. Kant and Fichte were subjective in temperament as well as in doctrine; Hegel saved himself by means of the influence of Spinoza. Rousseau and the romantic movement extended subjectivity from theory of knowledge to ethics and politics, and ended, logically, in complete anarchism such as that of Bakunin. This extreme of subjectivism is a form of madness.
Meanwhile science as technique was building up in practical men a quite different outlook from any that was to be found among theoretical philosophers. Technique conferred a sense of power: man is now much less at the mercy of his environment than he was in former times. But the power conferred by technique is social, not individual; an average individual wrecked on a desert island could have achieved more in the seventeenth century than he could now. Scientific technique requires the co-operation of a large number of individuals organized under a single direction. Its tendency, therefore, is against anarchism and even individualism, since it demands a well-knit social structure. Unlike religion, it is ethically neutral: it assures men that they can perform wonders, but does not tell them what wonders to perform. In this way it is incomplete. In practice, the purposes to which scientific skill will be devoted depend largely on chance. The men at the head of the vast organizations which it necessitates can, within limits, turn it this way or that as they please. The power impulse thus has a scope which it never had before. The philosophies that have been inspired by scientific technique are power philosophies, and tend to regard everything non-human as mere raw material. Ends are no longer considered; only the skilfulness of the process is valued. This also is a form of madness. It is, in our day, the most dangerous form, and the one against which a sane philosophy should provide an antidote.
The ancient world found an end to anarchy in the Roman Empire, but the Roman Empire was a brute fact, not an idea. The Catholic world sought an end to anarchy in the Church, which was an idea, but was never adequately embodied in fact. Neither the ancient nor the medieval solution was satisfactory—the one because it could not be idealized, the other because it could not be actualized. The modern world, at present, seems to be moving towards a solution like that of antiquity: a social order imposed by force, representing the will of the powerful rather than the hopes of common men. The problem of a durable and satisfactory social order can only be solved by combining the solidity of the Roman Empire with the idealism of St Augustine's City of God. To achieve this a new philosophy will be needed.