History of Modern Philosophy · Chapter 39%part II. From Kant to the Present Time.% (18)
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The positive stage of a science, which begins when we learn to explain phenomena by their laws, is preceded by two others: a theological stage, which ascribes phenomena to supposed personal powers, and a metaphysical stage, which ascribes them to abstract natural forces. These three periods denote the childhood, the youth, and the manhood of science.
The earliest view of the world is the theological view, which derives the events of the world from the voluntary acts of supernatural intelligent beings. The crude view of nature sees in each individual thing a being animated like man; later man accustoms himself to think of a whole class of objects as governed by one invisible being, by a divinity; finally the multitude of divinities gives place to a single God, who creates, maintains, and rules the universe, and by extraordinary acts, by miracles, interferes in the course of events. Thus fetichism (in its highest form, astrolatry), polytheism, and monotheism are the stages in the development of the theological mode of thought. In the second, the metaphysical, period, the acts of divine volition are replaced by entities, by abstract concepts, which are regarded as realities, as the true reality back of phenomena. A force, a power, an occult property or essence is made to dwell in things; the mysterious being which directs events is no longer called God, but "Nature," and invested with certain inclinations, with a horror of a vacuum, an aversion to breaks, a tendency toward the best, a vis medicatrix, etc. Here belong, also, the vegetative soul of Aristotle, the vital force and the plastic impulse of modern investigators. Finally the positive stage is reached, when all such abstractions, which are even yet conceived as half personal and acting voluntarily, are abandoned, and the unalterable and universally valid laws of phenomena established by observation and experiment alone. But to explain the laws of nature themselves transcends, according to Comte, the fixed limits of human knowledge. The beginning of the world lies outside the region of the knowable, atheism is no better grounded than the theistic hypothesis, and if Comte asserts that a blindly acting mechanism is less probable than a world-plan, he is conscious that he is expressing a mere conjecture which can never be raised to the rank of a scientific theory. The origin and the end of things are insoluble problems, in answering which no progress has yet been made in spite of man's long thought about them. Only that which lies intermediate between the two inscrutable termini of the world is an object of knowledge.
It is not only the human mind in general that exhibits this advance from the theological, through the metaphysical, to the positive mode of thought, but each separate science goes through the same three periods—only that the various disciplines have developed with unequal rapidity. While some have already culminated in the positive method of treatment, others yet remain caught in the theological period of beginnings, and others still are in the metaphysical transition stage. Up to the present all three phases of development exist side by side, and even among the objects of the most highly developed sciences there are some which we continue to regard theologically; these are the ones which we do not yet understand how to calculate, as the changes of the weather or the spread of epidemics. Which science first attained the positive state, and in what order have the others followed? With this criterion Comte constructs his classification of the sciences, in which, however, he takes account only of those sciences which he calls abstract, that is, those which treat of "events" in distinction from "objects." The abstract sciences (as biology) investigate the most general laws of nature, valid for all phenomena, from which the particular phenomena which experience presents to us cannot be deduced, but on the basis of which an entirely different world were also possible. The concrete sciences, on the other hand (e.g., botany and zoölogy), have to do with the actually given combinations of phenomena. The former follow out each separate one of the general laws through all its possible modes of operation, the latter consider only the combination of laws given in an object. Thus oaks and squirrels are the result of very many laws, inasmuch as organisms are dependent not only on biological, but also on physical, chemical, and mathematical laws.
Comte enumerates six of these abstract sciences, and arranges them in such a way that each depends on the truths of the preceding, and adds to these its own special truths, while the first (the most general and simplest) presupposes no earlier laws whatever, but is presupposed by all the later ones. According to this principle of increasing particularity and complexity the following scale results: (i) Mathematics, in which the science of number, as being absolutely without presuppositions, precedes geometry and mechanics; (2) Astronomy; (3) Physics (with five subordinate divisions, in which the first place belongs to the theory of weight, and the last to electrology, while the theory of heat, acoustics, and optics are intermediate); (4) Chemistry; (5) Biology or physiology; (6) Sociology or the science of society. This sequence, which is determined by the increasing complexity and increasing dependence of the objects of the sciences, is the order in which they have historically developed—before the special laws of the more complicated sciences can be ascertained, the general laws of the more simple ones must be accurately known. It is also advisable to follow this same order of increasing complexity and difficulty in the study of the sciences, for acquaintance with the methods of those which are elementary is the best preparation for the pursuit of the higher ones. In arithmetic and geometry we study positivity at its source; in the sociological spirit it finds its completion.
Mathematics entered on its positive stage at quite an early period, chemistry and biology only in recent times, while, in the highest and most complicated science, the metaphysical (negative, liberal, democratic, revolutionary) mode of thought is still battling with the feudalism of the theological mode. To make sociology positive is the mission of the second half of Comte's work, and to this goal his philosophical activity had been directed from the beginning. Comte rates the efforts of political economy very low, with the exception of the work of Adam Smith, and will not let them pass as a preparation for scientific sociology, holding that they are based on false abstractions. Psychology, which is absent from the above enumeration, is to form a branch of biology, and exclusively to use the objective method, especially phrenology (to the three faculties of the soul, "heart, character, and intellect," correspond three regions of the brain). Self-observation, so Comte, making an impossibility out of a difficulty, teaches, can at most inform us concerning our feelings and passions, and not at all concerning our own thinking, since reflection brings to a stop the process to which it attends, and thus destroys its object. The sole source of knowledge is external sense-perception. In his Positive Polity Comte subsequently added a seventh fundamental science, ethics or anthropology.
Sociology,[1] the elevation of which to the rank of a positive science is the principal aim of our philosopher, uses the same method as the natural sciences, namely, the interrogation and interpretation of experience by means of induction and deduction, only that here the usual relation of these two instruments of knowledge is reversed. Between inorganic and organic philosophy, both of which proceed from the known to the unknown, there is this difference, that in the former the advance is from the elements, as that which alone is directly accessible, to the whole which is composed of them, while in the latter the opposite is the case, since here the whole is better known than the individual parts of which it consists. Hence, in inorganic science the laws of the composite phenomena are obtained by deduction (from the laws of the simple facts inductively discovered) and confirmed by observation; in sociology, on the other hand, the laws are found through (historical) experience, and deductively verified (from the nature of man as established by biology) only in the sequel. Since the phenomena of society are determined not merely by the general laws of human nature, but, above all, by the growing influence of the past, historical studies must form the basis of sociological inquiry.
[Footnote 1: Cf. Krohn: Beiträge zur Kenntniss und Würdigung der Soziologie, Jahrbücher für Nationalökonomie und Statistik, New Series, vols. i. and iii., 1880 and 1881.]
Of the two parts of sociology, the Statics, which investigates the equilibrium (the conditions of the existence, the permanence, and the coexistence of social states), and Dynamics, which investigates the movement (the laws of the progress) of social phenomena, the first was in essence established by Aristotle. The fundamental concept of the Statics is the consensus, the harmony, solidarity, or mutual dependence of the members of the social organism. All its parts, science, art, religion, politics, industry, must be considered together; they stand in such intimate harmony and correlation that, for every important change of condition in one of these parts, we may be certain of finding corresponding changes in all the others, as its causes and effects. Besides the selfish propensities, there dwell in man an equally original, but intrinsically weaker, impulse toward association, which instinctively leads him to seek the society of his fellows without reflection on the advantages to be expected therefrom, and a moderate degree of benevolence. As altruism conflicts with egoism, so the reason, together with the impulse to get ahead, which can only be satisfied through labor, is in continual conflict with the inborn disinclination to regulated activity (especially to mental effort). The character of society depends on the strength of the nobler incentives, that is, the social inclinations and intellectual vivacity in opposition to the egoistic impulses and natural inertness. The former nourish the progressive, the latter the conservative spirit. Women are as much superior to men in the stronger development of their sympathy and sociability as they are inferior in insight and reason. Society is a group of families, not of individuals, and domestic life is the foundation, preparation, and pattern for social life, Comte praises the family, the connecting link between the individual and the species, as a school of unselfishness, and approves the strictness of the Catholic Church in regard to the indissolubility of the marriage relation. He remarks the evil consequences of the constantly increasing division of labor, which makes man egoistic and narrow-minded, since it hides rather than reveals the social significance of the employment of the individual and its connection with the welfare of the community, and seeks for a means of checking them. Besides the universal education of youth, he demands the establishment of a spiritual power to bring the general interest continually to the minds of the members of all classes and avocations, to direct education, and to enjoy the same authority in moral and intellectual matters as is conceded to the astronomer in the affairs of his department. The function of this power would be to occupy the position heretofore held by the clergy. Comte conceives it as composed of positive philosophers, entirely independent of the secular authorities, but in return cut off from political influence and from wealth. Secular authority, on the other hand, he wishes put into the hands of an aristocracy of capitalists, with the bankers at the head of these governing leaders of industry.
The Dynamics, the science of the temporal succession of social phenomena, makes use of the principle of development. The progress of society, which is to be regarded as a great individual, consists in the growing predominance of the higher, human activities over the lower and animal. The humanity in us, it is true, will never attain complete ascendency over the animality, but we can approach nearer and nearer to the ideal, and it is our duty to aid in this march of civilization. Although the law of progress holds good for all sides of mental life, for art, politics, and morals, as well as for science, nevertheless the most important factor in the evolution of the human race is the development of the intellect as the guiding power in us (though not in itself the strongest). Awakened first by the lower wants, the intellect assumes in increasing measure the guidance of human operations, and gives a determinate direction to the feelings. The passions divide men, and, without the guidance of the speculative faculty, would mutually cripple one another; that which alone unites them into a collection force is a common belief, an idea. Ideas are related to feeling—to quote a comparison from John Stuart Mill's valuable treatise Auguste Comte and Positivism, 3d ed., 1882, a work of which we have made considerable use—as the steersman who directs the ship is to the steam which drives it forward. Thus the history of humanity has been determined by the history of man's intellectual convictions, and this in turn by the three familiar stages in the theory of the universe. With the development from the theological to the positive mode of thought is most intimately connected, further, the transition from the military to the industrial mode of life. As the religious spirit prepares the way for the scientific spirit, so without the dominion of the military spirit industry could not have been developed. It was only in the school of war that the earliest societies could learn order; slavery was beneficial in that through it labor was imposed upon the greater part of mankind in spite of their aversion to it. The political preponderance of the legists corresponds to the intermediate, metaphysical stage. The sociological law (discovered by Comte in the year 1822) harmonizes also with the customary division which separates the ancient from the modern world by the Middle Ages.
In his philosophy of history Comte gives the further application of these principles. Here he has won commendation even from his opponents for a sense of justice which merits respect and for his comprehensive view. The outlooks and proposals for the future here interspersed were in later writings[1] worked out into a comprehensive theory of the regeneration of society; the extravagant character of which has given occasion to his critics to make a complete division between the second, "subjective or sentimental," period of his thinking, in which the philosopher is said to be transformed into the high priest of a new religion, and the first, the positivistic period, although the major part of the qualities pointed out as characteristic of the former are only intensifications of some which may be shown to have been present in the latter. Beneath the surface of the most sober inquiry mystical and dictatorial tendencies pulsate in Comte from the beginning, and science was for him simply a means to human happiness. But now he no longer demands the independent pursuit of science in order to the attainment of this end, but only the believing acceptance of its results. The intellect is to be placed under the dominion of the heart, and only such use made of it as promises a direct advantage for humanity; the determination of what problems are most important at a given time belongs to the priesthood. The systematic unity or harmony of the mind demands this dominion of the feelings over thought. The religion of positivism, which has "love for its principle, order for its basis, and progress for its end," is a religion without God, and without any other immortality than a continuance of existence in the grateful memory of posterity. The dogmas of the positivist religion are scientific principles. Its public cultus with nine sacraments and a large number of annual festivals, is paid to the Grand Être "Humanity" (which is not omnipotent, but, on account of its composite character, most dependent, yet infinitely superior to any of its parts); and, besides this, space, the earth, the universe, and great men of the past are objects of reverence. Private devotion consists in the adoration of living or dead women as our guardian angels. The ethics of the future declares the good of others to be the sole moral motive to action (altruism). Comte's last work, the Philosophy of Mathematics, 1856, indulges in a most remarkable numerical mysticism. The historical influence exercised by Comte through his later writings is extremely small in comparison with that of his chief work. Besides Blignières and Robinet, E. Littré, the well-known author of the Dictionnaire de la Langue Française (1863 seq.) who was the most eminent of Comte's disciples and the editor of his Collected Works (1867 seq.), has written on the life and work of the master. Comte's school divided into two groups—the apostates, with Littré (1801-81) at their head, who reject the subjective phase and hold fast to the earlier doctrine, and the faithful, who until 1877, when a new division between strict and liberal Comteans took place within this group, gathered about P. Laffitte (born 1823).[2] The leader of the English positivists is Frederic Harrison (born 1831). Positivistic societies exist also in Sweden, Brazil, Chili, and elsewhere. Positivism has been developed in an independent spirit by J.S. Mill and Herbert Spencer.
[Footnote 1: Positivist Catechism, 1852 [English translation by Congreve, 1858, 2d ed., 1883]; System of Positive Polity, 4 vols., 1851-54 [English translation, 1875-77]. Cf. Pünjer, A. Comtes "Religion der Menschheit" in the Jahrbücher für protestantische Theologie, 1882.]
[Footnote 2: On this division cf. E. Caro, M. Littré et le Positivisme, 1883, and Herm. Gruber (S.J.), Der Positivismus vom Tode Comtes bis auf unsere Tage, 1891.]
The following brief remarks on the course of French philosophy may also be added. Against the sensationalism of Condillac as continued by Cabanis, Destutt de Tracy (see above, pp. 259-260), and various physiologists, a twofold reaction asserted itself. One manifestation of this proceeded from the theological school, represented by the "traditionalists" Victor de Bonald (1818), Joseph de Maistre (1753-1821; St. Petersburg Soirées, 1821), and F. de Lamennais (1782-1854), who, however, after his break with the Church (Words of a Believer, 1834) developed in his Sketch of a Philosophy, 1841 seq., an ontological system after Italian and German models. The other came from the spiritualistic school, at whose head stood Maine de Biran[1] (1766-1824; On the Foundations of Psychology; his Works have been edited by Cousin, 1841, Naville, 1859, and Bertrand) and Royer Collard (1763-1845). Their pupil Victor Cousin (1792-1867; Works, 1846-50), who admired Hegel also, became the head of the eclectic school. Cousin will neither deny metaphysics with the Scotch, nor construe metaphysics a priori with the Germans, but with Descartes bases it on psychology. For a time an idealist of the Hegelian type (infinite and finite, God and the world, are mutually inseparable; the Ideas reveal themselves in history, in the nations, in great men), he gradually sank back to the position of common sense. His adherents, among whom Théodore Jouffroy (died 1842) was the most eminent, have done special service in the history of philosophy. From Cousin's school, which was opposed by P. Leroux and J. Reynaud, have come Ravaisson, Saisset, Jules Simon, P. Janet (born 1823),[2] and E. Caro (born 1826; The Philosophy of Goethe, 1866). Kant has influenced Charles Renouvier (born 1817; Essays in General Criticism, 4 vols., 1854-64) and E. Vacherot (born 1809; Metaphysics and Science, 1858, 2d ed., 1863; Science and Consciousness, 1872).
[Footnote 1: Cf. E. König in Philosophische Monatshefte, vol. xxv. 1889, p.160 seq.]
[Footnote 2: Janet: History of Political Science in its Relations to Morals, 1858, 3d ed., 1887; German Materialism of the Present Day, 1864, English translation by Masson, 1866: The Family, 1855; The Philosophy of Happiness, 1862; The Brain and Thought, 1867; Elements of Morals, 1869 [English translation by Corson, 1884]; The Theory of Morals, 1874 [English translation by Mary Chapman, 1883]; Final Causes, 1876 [English translation by Affleck, with a preface by Flint, new ed., 1883].]
Among other thinkers of reputation we may mention the socialist Henri de Saint-Simon (1760-1825; Selected Works, 1859), the physiologist Claude Bernard (1813-78), the positivist H. Taine (1828-93; The Philosophy of Art, English translation by Durand, 2d ed., 1873; On Intelligence, 1872, English translation by Haye, 1871), E. Renan (1823-92; The Life of Jesus, 1863, English translation by Wilbour, Philosophical Dialogues and Fragments—English, 1883), the writer on aesthetics and ethics J.M. Guyau (The Problems of Contemporary Aesthetics, 1884; Sketch of an Ethic without Obligation or Sanction, 1885; The Irreligion of the Future, 1887), Alfred Fouillée (The Future of Metaphysics founded on Experience, 1889; Morals, Art, and Religion according to Guyau, 1889; The Evolutionism of the Idea-Forces, 1890), and the psychologist Th. Ribot,[1] editor of the Revue Philosophique (from 1876).
[Footnote 1: Ribot: Heredity, 2d ed., 1882 [English translation, 1875]; The Diseases of Memory, 1881 [English translation, 1882]; The Diseases of the Will, 1883 [English. 1884]; The Diseases of Personality, 1885 [English, 1887]; The Psychology of Attention, 1889 [English, 1890]; German Psychology of To-day, 2d ed., 1885 [English translation by Baldwin, 1886].]
%3. Great Britain and America.%
Prominent among the British philosophers of the nineteenth century[1] are Hamilton, Bentham, J.S. Mill, and Spencer. Hamilton is the leading representative of the Scottish School; Bentham is known as the advocate of utilitarianism; Mill, an exponent of the traditional empiricism of English thinking, develops the theory of induction and the principle of utility; Spencer combines an agnostic doctrine of the absolute and thoroughgoing evolution in the phenomenal world into a comprehensive philosophical system.[2] In recent years there has been a reaction against empirical doctrines on the basis of neo-Kantian and neo-Hegelian principles. Foremost among the leaders of this movement we may mention T.H. Green.
[Footnote 1: Cf. Harald Höffding, Einleitung in die englische Philosophie unserer Zeit (Danish, 1874), German (with alterations and additions by the author) by H. Kurella, 1889; David Masson, Recent British Philosophy, 1865, 3d ed., 1877; Ribot, La Psychologie Anglaise Contemporaine, 1870, 2d ed., 1875 [English, 1874] Guyau, La Morale Anglaise Contemporaine, 1879 [Morris, British Thought and Thinkers, 1880; Porter, "On English and American Philosophy," Ueberweg's History, English translation, vol. ii. pp. 348-460; O. Pfleiderer, Development of Theology, 1890, book iv.—TR.]]
[Footnote 2: Cf. on Mill and Spencer, Bernh. Pünjer, Jahrbücher für protestantische Theologie, 1878.]
The Scottish philosophy has been continued in the nineteenth century by James Mackintosh (Dissertation on the Progress of Ethical Philosophy, 1830, 3d ed., 1863), and William Whewell (History of the Inductive Sciences, 3d ed., 1857; Philosophy of the Inductive Sciences, 1840, 3d ed., 1858-60). Its most important representative is Sir William Hamilton[1] of Edinburgh (1788-1856), who, like Whewell, is influenced by Kant. Hamilton bases philosophy on the facts of consciousness, but, in antithesis to the associational psychology, emphasizes the mental activity of discrimination and judgment. Our knowledge is relative, and relations its only object. Consciousness can never transcend itself, it is bound to the antithesis of subject and object, and conceives the existent under relations of space and time. Hence the unconditioned is inaccessible to knowledge and attainable by faith alone. Among Hamilton's followers belong Mansel (Metaphysics, 3d. ed., 1875; Limits of Religions Thought, 5th ed., 1870) and Veitch. The Scottish doctrine was vigorously opposed by J.F. Ferrier (1808-64; Institutes of Metaphysics, 2d ed., 1856), who himself developed an idealistic standpoint.
[Footnote 1: Hamilton: Discussions on Philosophy and Literature, 1852, 3d ed., 1866; Lectures on Metaphysics, 2d ed., 1860, and on Logic, 2d ed., 1866, edited by his pupils, Mansel and Veitch; Reid's Works, with notes and dissertations, 1846, 7th ed., 1872. On Hamilton cf. Veitch, 1882, 1883 [Monck, 1881].]
In the United States the Scottish philosophy has exercised a wide influence. In recent times it has been strenuously advocated, chiefly in the spirit of Reid, by James McCosh (a native of Scotland, but since 1868 in America; The Intuitions of the Mind, 3d ed., 1872; The Laws of Discursive Thought, new ed., 1891; First and Fundamental Truths, 1889); while in Noah Porter (died 1892; The Human Intellect, new ed., 1876; The Elements of Moral Science, 1885) it appears modified by elements from German thinking.
Jeremy Bentham[1] (1748-1832) is noteworthy for his attempt to revive Epicureanism in modern form. Virtue is the surest means to pleasure, and pleasure the only self-evident good. Every man strives after happiness, but not every one in the right way. The honest man calculates correctly, the criminal falsely; hence a careful calculation of the value of the various pleasures, and a prudent use of the means to happiness, is the first condition of virtue; in this the easily attainable minor joys, whose summation amounts to a considerable quantum, must not be neglected. The value of a pleasure is measured by its intensity, duration, certainty, propinquity, fecundity in the production of further pleasure, purity or freedom from admixture of consequent pain, and extent to the greatest possible number of persons. Every virtuous action results in a balance of pleasure. Inflict no evil on thyself or others from which a balance of good will not result. The end of morality is the "greatest happiness of the greatest number," in the production of which each has first to care for his own welfare: whoever injures himself more than he serves others acts immorally, for he diminishes the sum of happiness in the world; the interest of the individual coincides with the interest of society. The two classes of virtues are prudence and benevolence. The latter is a natural, though not a disinterested affection: happiness enjoyed with others is greater than happiness enjoyed alone. Love is a pleasure-giving extension of the individual; we serve others to be served by them.
[Footnote 1: Bentham: Introduction to the Principles of Morals and Legislation, 1789; new ed., 1823, reprinted 1876; Deontology, 1834, edited by Bowring, who also edited the Works, 1838-43. The Principles of Civil and Criminal Legislation, edited in French from Bentham's manuscripts by his pupil Etienne Dumont (1801, 2d ed., 1820; English by Hildreth, 5th ed., 1887), was translated into German with notes by F.E. Beneke, 1830.]
Associationalism has been reasserted by James Mill (1773-1836; Analysis of the Phenomena of the Human Mind, 1829), whose influence lives on in the work of his greater son. The latter, John Stuart Mill,[1] was born in London 1806, and was from 1823 to 1858 a secretary in the India House; after the death of his wife he lived (with the exception of two years of service as a Member of Parliament) at Avignon; his death occurred in 1873. Mill's System of Logic appeared in 1843, 9th ed., 1875; his Utilitarianism, 1863, new ed., 1871; An Examination of Sir William Hamilton's Philosophy, 1865, 5th ed., 1878; his notes to the new edition of his father's work, Analysis of the Phenomena of the Human Mind, 2d ed., 1878, also deserve notice. With the phenomenalism of Hume and the (somewhat corrected) associational psychology of his father as a basis, Mill makes experience the sole source of knowledge, rejecting a priori and intuitive elements of every sort. Matter he defines as a "permanent possibility of sensation"; mind is resolved into "a series of feelings with a background of possibilities of feeling," even though the author is not unaware of the difficulty involved in the question how a series of feelings can be aware of itself as a series. Mathematical principles, like all others, have an experiential origin—the peculiar certitude ascribed to them by the Kantians is a fiction—and induction is the only fruitful method of scientific inquiry (even in mental science). The syllogism is itself a concealed induction.
[Footnote 1: Cf. on Mill. Taine, Le Positivisme Anglais, 1864 [English, by Haye]; the objections of Jevons (Contemporary Review, December, 1877 seq., reprinted in Pure Logic and other Minor Works, 1890; cf. Mind, vol. xvi. pp. 106-110) to Mill's doctrine of the inductive character of geometry, his treatment of the relation of resemblance, and his exposition of the four methods of experimental inquiry in their relation to the law of causation; and the finely conceived essay on utilitarianism, by C. Hebler, Philosophische Aufsãtze, 1869, pp. 35-66. [Also Mill's own Autobiography, 1873: Bain's John Stuart Mill, a Criticism, 1882; and T.H. Green, Lectures on the Logic, Works, vol. ii.—TR.]]
When I assert the major premise the inference proper is already made, and in the conclusion the comprehensive formula for a number of particular truths which was given in the premise is merely explicated, interpreted. Because universal judgments are for him merely brief expressions for aggregates of particular truths, Mill is able to say that all knowledge is generalization, and at the same time to argue that all inference is from particulars to particulars. Inference through a general proposition is not necessary, yet useful as a collateral security, inasmuch as the syllogistic forms enable us more easily to discover errors committed. The ground of induction, the uniformity of nature in reference both to the coexistence and the succession of phenomena, since it wholly depends on induction, is not unconditionally certain; but it may be accepted as very highly probable, until some instance of lawless action (in itself conceivable) shall have been actually proved. Like the law of causation, the principles of logic are also not a priori, but only the highest generalizations from all previous experience.
Mill's most brilliant achievement is his theory of experimental inquiry, for which he advances four methods: (1) The Method of Agreement: "If two or more instances of the phenomenon under investigation have only one circumstance in common, the circumstance in which alone all the instances agree is the cause (or effect) of the given phenomenon." (2) The Method of Difference: "If an instance in which the phenomenon under investigation occurs, and an instance in which it does not occur, have every circumstance in common save one, that one occurring only in the former; the circumstance in which alone the two instances differ, is the effect, or the cause, or an indispensable part of the cause, of the phenomenon," These two methods (the method of observation, and the method of artificial experiment) may also be employed in combination, and the Canon of the Joint Method of Agreement and Difference runs: "If two or more instances in which the phenomenon occurs have only one circumstance in common, while two or more instances in which it does not occur have nothing in common save the absence of that circumstance, the circumstance in which alone the two sets of instances differ is the effect, or the cause, or an indispensable part of the cause, of the phenomenon." (3) The Method of Residues: "Subduct from any phenomenon such part as is known by previous inductions to be the effect of certain antecedents, and the residue of the phenomenon is the effect of the remaining antecedents." (4) The Method of Concomitant Variations: "Whatever phenomenon varies in any manner whenever another phenomenon varies in some particular manner, is either a cause or an effect of that phenomenon, or is connected with it through some fact of causation." When the phenomena are complex the deductive method must be called in to aid: from the inductively ascertained laws of the action of single causes this deduces the laws of their combined action; and, as a final step, the results of such ratiocination are verified by the proof of their agreement with empirical facts. To explain a phenomenon means to point out its cause; the explanation of a law is its reduction to other, more general laws. In all this, however, we remain within the sphere of phenomena; the essence of nature always eludes our knowledge.