Two periods may be distinguished in the Cartesian era,—one in which the method, in its newness, is often misconceived; the other, in which one is forced, at least, to re-enter the salutary way opened by Descartes. To the first belong Malebranche, Spinoza, Leibnitz himself; to the second, the philosophers of the eighteenth century.
Without doubt Malebranche, upon some points, descended very far into interior investigation; but most of the time he gave himself up to wander in an imaginary world, and lost sight of the real world. It is not a method that is wanting to Spinoza, but a good method; his error consists in having applied to philosophy the geometrical method, which proceeds by axioms, definitions, theorems, corollaries; no one has made less use of the psychological method; that is the principle and the condemnation of his system. The Nouveaux Essais sur l'Entendement Humain exhibit Leibnitz opposing observation to observation, analysis to analysis; but his genius usually hovers over science, instead of advancing in it step by step; hence the results at which he arrives are often only brilliant hypotheses, for example, the pre-established harmony, now relegated among the analogous hypotheses of occasional causes and a plastic mediator. In general, the philosophy of the seventeenth century, by not employing with sufficient rigor and firmness the method with which Descartes had armed it, produced little else than systems, ingenious without doubt, bold and profound, but often also rash,—systems that have failed to keep their place in science.[7] In fact, nothing is durable except that which is founded upon a sound method; time destroys all the rest; time, which re-collects, fecundates, aggrandizes the least germs of truth deposited in the humblest analyses, strikes without pity, engulfs hypotheses, even those of genius. Time takes a step, and arbitrary systems are overturned; the statues of their authors alone remain standing over their ruins. The task of the friend of truth is to search for the useful remains of them, that survive and can serve for new and more solid constructions.
The philosophy of the eighteenth century opens the second period of the Cartesian era; it proposed to itself to apply the method already discovered and too much neglected,—it applied itself to the analysis of thought. Disabused of ambitious and sterile attempts, and, like Descartes, disdainful of the past, the eighteenth century dared to think that every thing in philosophy was to be done over again, and that, in order not to wander anew, it was necessary to set out with the modest study of man. Instead, therefore, of building up all at once systems risked upon the universality of things, it undertook to examine what man knows, what he can know; it brought back entire philosophy to the study of our faculties, as physics had just been brought back to the study of the properties of bodies,—which was giving to philosophy, if not its end, at least its true beginning.
The great schools which divide the eighteenth century are the English and French school, the Scotch school, and the German school, that is to say, the school of Locke and Condillac, that of Reid, that of Kant. It is impossible to misconceive the common principle which animates them, the unity of their method. When one examines with impartiality the method of Locke, he sees that it consists in the analysis of thought; and it is thereby that Locke is a disciple, not of Bacon and Hobbes, but of our great countryman, Descartes.[8] To study the human understanding as it is in each one of us, to recognize its powers, and also its limits, is the problem which the English philosopher proposed to himself, and which he attempted to solve. I do not wish to judge here of the solution which he gave of this problem; I limit myself to indicating clearly what was for him the fundamental problem. Condillac, the French disciple of Locke, made himself everywhere the apostle of analysis; and analysis was also in him, or at least should have been, the study of thought. No philosopher, not even Spinoza, has wandered farther than Condillac[9] from the true experimental method, and has strayed farther on the route of abstractions, even verbal abstractions; but, strange enough, no one is severer than he against hypotheses, save that of the statue-man. The author of the Traité des Sensations has very unfaithfully practised analysis; but he speaks of it without cessation. The Scotch school combats Locke and Condillac; it combats them, but with their own arms, with the same method which it pretends to apply better.[10] In Germany, Kant wishes to replace in light and honor the superior element of human consciousness, left in the shade, and decried by the philosophy of his times; and for that end, what does he do? He undertakes a profound examination of the faculty of knowing; the title of his principal work is, Critique of Pure Reason;[11] it is a critique, that is to say again, an analysis; the method of Kant is then no other than that of Locke and Reid. Follow it until it reaches the hands of Fichte,[12] the successor of Kant, who died but a few years since; there, again, the analysis of thought is given as the foundation of philosophy. Kant was so firmly established in the subject of knowledge, that he could scarcely go out of it—that, in fact, he never did legitimately go out of it. Fichte plunged into the subject of knowledge so deeply that he buried himself in it, and absorbed in the human me all existences, as well as all sciences—sad shipwreck of analysis, which signalizes at once its greatest effort and its rock!
The same spirit, therefore, governs all the schools of the eighteenth century; this century disdains arbitrary formulas; it has a horror for hypotheses, and attaches itself, or pretends to attach itself, to the observation of facts, and particularly to the analysis of thought.
Let us acknowledge with freedom and with grief, that the eighteenth century applied analysis to all things without pity and without measure. It cited before its tribunal all doctrines, all sciences; neither the metaphysics of the preceding age, with their imposing systems, nor the arts with their prestige, nor the governments with their ancient authority, nor the religions with their majesty,—nothing found favor before it. Although it spied abysses at the bottom of what it called philosophy, it threw itself into them with a courage which is not without grandeur; for the grandeur of man is to prefer what he believes to be truth to himself. The eighteenth century let loose tempests. Humanity no more progressed, except over ruins. The world was again agitated in that state of disorder in which it had already been once seen, at the decline of the ancient beliefs, and before the triumphs of Christianity, when men wandered through all contraries, without power to rest anywhere, given up to every disquietude of spirit, to every misery of heart, fanatical and atheistical, mystical and incredulous, voluptuous and sanguinary.[13] But if the philosophy of the eighteenth century has left us a vacuity for an inheritance, it has also left us an energetic and fecund love of truth. The eighteenth century was the age of criticism and destructions; the nineteenth should be that of intelligent rehabilitations. It belongs to it to find in a profounder analysis of thought the principles of the future, and with so many remains to raise, in fine, an edifice that reason may be able to acknowledge.
A feeble but zealous workman, I come to bring my stone; I come to do my work; I come to extract from the midst of the ruins what has not perished, what cannot perish. This course is at once a return to the past, an effort towards the future. I propose neither to attack nor to defend any of the three great schools that divide the eighteenth century. I will not attempt to perpetuate and envenom the warfare which divides them, complacently designating the differences which separate them, without taking an account of the community of method which unites them. I come, on the contrary, a devoted soldier of philosophy, a common friend of all the schools which it has produced, to offer to all the words of peace.
The unity of modern philosophy, as we have said, resides in its method, that is to say, in the analysis of thought—a method superior to its own results, for it contains in itself the means of repairing the errors that escape it, of indefinitely adding new riches to riches already acquired. The physical sciences themselves have no other unity. The great physicians who have appeared within two centuries, although united amongst themselves by the same point of departure and by the same end, generally accepted, have nevertheless proceeded with independence and in ways often opposite. Time has re-collected in their different theories the part of truth that produced them and sustained them; it has neglected their errors from which they were unable to extricate themselves, and uniting all the discoveries worthy of the name, it has little by little formed of them a vast and harmonious whole. Modern philosophy has also been enriched during the two centuries with a multitude of exact observations, of solid and profound theories, for which it is indebted to the common method. What has hindered her from progressing at an equal pace with the physical sciences whose sister she is? She has been hindered by not understanding better her own interests, by not tolerating diversities that are inevitable, that are even useful, and by not profiting by the truths which all the particular doctrines contain, in order to deduce from them a general doctrine, which is successively and perpetually purified and aggrandized.
Not, indeed, that I would recommend that blind syncretism which destroyed the school of Alexandria, which attempted to bring contrary systems together by force; what I recommend is an enlightened eclecticism, which, judging with equity, and even with benevolence, all schools, borrows from them what they possess of the true, and neglects what in them is false. Since the spirit of party has hitherto succeeded so ill with us, let us try the spirit of conciliation. Human thought is immense. Each school has looked at it only from its own point of view. This point of view is not false, but it is incomplete, and moreover, it is exclusive. It expresses but one side of truth, and rejects all the others. The question is not to decry and recommence the work of our predecessors, but to perfect it in reuniting, and in fortifying by that reunion, all the truths scattered in the different systems which the eighteenth century has transmitted to us.
Such is the principle to which we have been conducted by two years of study upon modern philosophy, from Descartes to our times. This principle, badly disengaged at first, we applied for the first time within the narrowest limits, and only to theories relative to the question of personal existence.[14] We then extended it to a greater number of questions and theories; we touched the principal points of the intellectual and moral order,[15] and at the same time that we were continuing the investigations of our illustrious predecessor, M. Royer-Collard, upon the schools of France, England, and Scotland, we commenced the study new among us, the difficult but interesting and fecund study, of the philosophy of Kœnigsberg. We can at the present time, therefore, embrace all the schools of the eighteenth century, and all the problems which they agitated.