Philosophy

Before philosophy had established itself in the Greek cities as a respectable calling, the philosopher was an object of comic suspicion, and no writer has given that suspicion a more lasting form than Aristophanes. In the Clouds, produced in 423 BC and afterward revised, a version of Socrates keeps a school called the Thinkery, where master and disciples stoop over the earth to investigate gnats and fleas or hang suspended in baskets the better to contemplate the heavens. To them comes the farmer Strepsiades, driven by debt to seek from the new learning a rhetorical skill that will let him cheat his creditors. What he finds looks to his commonsense eye like a mixture of astronomy, impiety, physical speculation, and sophistic argument, carried on in rags and hunger for reasons never made clear.

The caricature is unjust to the Socrates known from Plato and Xenophon, and Plato in the Apology cites the play as one source of the prejudice which brought Socrates to trial. It would be a mistake, however, to treat it as mere slander. Aristophanes gives comic form to an objection which ordinary Athenians did hold against the new class of thinkers, and which the defenders of philosophy have had to answer since. The objection is that philosophy draws the young man away from the duties binding him to family and city, fills him with doubts about the gods his father honored, and leaves him with tools of argument usable without scruple against the traditions that held the community together. The play ends with the Thinkery in flames.

The questions raised here belong to several neighboring ideas. The relation of philosophy to the traditional beliefs of the city is treated also under Religion and under Custom and Convention; whether instruction in argument can be separated from instruction in morals belongs to Rhetoric and Education. What is peculiar to the idea of Philosophy is the display of a case in which the philosophical life is viewed wholly from outside, by a man who has no share in its goods and sees only its external oddities, and in which the philosophical answer to that view has not yet been given.

Plato's defense of philosophy in the Republic and the Apology is written in awareness of the popular picture which the Clouds had fixed, and it is a commonplace of the scholarship to read his account of the philosopher as a reply to the comic one. Aristotle's separation of the philosophical from the political life, and his ranking of contemplation as the highest happiness, may be read as part of the same reply, though conducted in a calmer key. The objection itself does not disappear, and returns wherever the man of learning becomes, for reasons like those of Strepsiades, an object of the plain man's suspicion.

Plato's conception of philosophy takes its form from the figure of Socrates, a man condemned to death for practicing it. In the Apology, Socrates tells his judges that he will never cease from the practice and teaching of philosophy, and that the unexamined life is not worth living. Philosophy so conceived is less a body of doctrine than an activity, a persistent inquiry into what men suppose themselves to know. Socrates claims no wisdom of his own; his advantage over the poets, the politicians, and the craftsmen lies in his awareness of his ignorance, whereas they mistake competence in one province for understanding of the whole. Here appears the distinction, observed throughout antiquity, between the love of wisdom and its possession: a man not actually wise may be called a philosopher by virtue of his effort to become so.

In the Republic this practice is developed into an account of knowledge and of the order of being. The divided line separates opinion from knowledge and images from intelligible objects; dialectic, which Plato names the supreme form of knowledge, carries the mind from visible particulars to the Forms and finally to the Good, the source of being and of intelligibility in everything else. Philosophy is thus not one discipline among many but the discipline which comprehends the others by reaching the ground they hold in common. Whether the summit of knowledge should be called dialectic, as Plato holds, or theology, as Aristotle holds, is treated more fully under the ideas of Dialectic and Metaphysics, and the difference does not affect their agreement that the philosopher is a man of knowledge rather than of opinion.

The allegory of the cave presents the ascent in figure. The prisoners take shadows for realities; the one who escapes into sunlight is blinded at first, and on returning is mocked by those still in chains. Plato does not leave him above ground. The philosopher is brought back so that what he has seen may be put to use in governing his less fortunate fellows, which is the ground of the proposal that cities will have no rest until philosophers are kings or kings philosophize. His estimate of poetry runs the other way: the poet imitates imitations, moving among images and beliefs, while the philosopher rises above imagination to the ideas. Yet myth and poetry furnish materials from which philosophical insight is sometimes distilled, and in the Laws religious belief is joined with philosophy in the worship of the gods rather than set against it.

Much of the later discussion proceeds on terms Plato sets: that philosophy reaches a reality the senses do not disclose, and that this reaching carries a public obligation. The defense mounted in the Republic and the Apology answers the popular suspicion which Aristophanes had given comic form, claiming for the philosopher the very competence in civic affairs the comic poet denied him. Augustine gives the Platonists the highest place among the pagan schools because they acknowledged an immaterial and intelligible reality, and Aquinas, though Aristotelian in method, keeps the ordering of knowledge toward a wisdom lying beyond the particular sciences.

The Metaphysics opens with the observation that all men by nature desire to know, and Aristotle treats philosophy as the fullest expression of that desire, since it is knowledge sought for its own sake rather than for any advantage it brings. He traces an ascent from sensation through memory and experience to art and science, with wisdom at the summit. The wise man knows not merely that a thing is so but why it is so, grasping the first causes from which the rest follows. Since the word science here means knowledge as distinguished from opinion, philosophy and science are scarcely to be distinguished, and philosophy as a whole is divided into a number of sciences rather than set against them.

The divisions of philosophy occupy Aristotle at some length. He separates the theoretic sciences from the practical and the productive, according as they consider what is, what ought to be done, or what may be made. Within the theoretic order, physics studies natural and changeable beings, mathematics studies quantities abstracted from matter, and first philosophy, later called metaphysics, studies being as being together with the principles belonging to whatever exists insofar as it exists. This gives philosophy a universality the particular sciences lack, since it examines the foundations each of them presupposes. The principle of non-contradiction belongs to no particular science, because it governs all reasoning whatsoever. The bearing of these divisions on conduct is pursued under the ideas of Prudence and Virtue.

Against Plato, Aristotle holds that philosophy must begin from the world disclosed in experience rather than turn away from it. The Forms are not separate substances in a world apart; form and matter are found together in particular things, and sense-experience is the source from which, by induction, the principles of philosophical knowledge are obtained. Wonder at the visible world is therefore the beginning of philosophy and not an obstacle to it. On the ranking of the philosophical life the two men are nearer to agreement, since the Nicomachean Ethics describes contemplation as the activity most like the divine. Aristotle nevertheless distinguishes the philosophical from the political life and does not require the philosopher to govern, and he judges poetry more philosophical than history because it deals with the universal.

The account leaves a difficulty for those who inherit it. If the principles of each science are indemonstrable and known by intuition, it may be asked what prevents two sciences from resting on incompatible first principles. Aquinas answers that sacred doctrine, proceeding from the First Cause itself, can adjudicate where the philosophical sciences cannot, a claim examined under the idea of Theology. Bacon and Descartes take the other course, holding that the inherited principles must be set aside and the structure raised again on grounds any inquirer may verify. That Aquinas could call Aristotle simply the philosopher indicates how far these divisions of the sciences had come to define the subject.

Among the Roman writers the practice of philosophy tends to become more important than its content as a body of doctrine, and in Epictetus the tendency is carried furthest. A man who can recite Chrysippus but cannot govern his own desires has not, on this view, begun to philosophize. Philosophy is a discipline of the will, exercised daily in distinguishing what lies within our power from what does not. The Stoic does not withdraw into contemplation apart from the world; he meets illness, poverty, insult, and loss, and treats each as matter upon which virtue may be practiced. The lecture room, Epictetus says, is a hospital, and the student should leave it in pain rather than in pleasure. "Philosophy does not promise to secure to man anything outside himself."

The emphasis on practice is not a rejection of theory. Epictetus teaches the traditional Stoic curriculum of logic, physics, and ethics. But the study of syllogisms is undertaken so that a man may not be deceived, and the study of nature so that he may bring his will into accord with the rational order of the whole. Theory is ordered to practice rather than pursued for itself. Whether that ordering is the right one, and whether the contemplative or the active life is to be preferred, is discussed under the ideas of Happiness and Wisdom. Epictetus holds further that the calling admits of no combination with others: a man cannot be first a philosopher, then a tax-collector, then an orator, then one of Caesar's procurators.

The doctrine rests on a division between what depends upon our choice and what does not. Body, property, reputation, and public office lie outside our control; judgments, impulses, desires, and aversions belong to us. Philosophy is the art of holding the attention fixed upon this boundary, and the man who masters it is free in chains while the man who ignores it is a slave upon a throne. There seems to be little difference here between the Stoic and the Epicurean conception, since Lucretius also praises philosophy as that which quiets the terrors of the mind, though he attributes the benefit chiefly to the truth of its teaching about the constitution of the world.

This conception of philosophy as a moral discipline and a consolation gives the word the sense it carries in the familiar injunction to a person in distress to be philosophical, which means much what it means to say be stoical. Marcus Aurelius, writing in the same tradition, describes philosophy as a mother to whom one returns for solace, so that what one meets with in the court may be endured. Augustine, who found in Cicero the same summons to a way of life rather than to a set of opinions, keeps the practical emphasis while denying that unaided philosophy completes what it begins. The measure of philosophy by conduct rather than by argument is taken up again under the idea of Knowledge.

Augustine came to Christianity by way of philosophy. In the Confessions he recounts his youthful reading of Cicero's Hortensius, a lost dialogue exhorting the reader to the philosophical life, and describes the effect as a change in his prayers and in the whole direction of his desires. Philosophy awakened in him a longing for wisdom which no worldly good could satisfy, and which philosophy itself could not satisfy either. The Platonists, whom he read afterward, showed him that truth is immaterial and eternal, but not the way of humility by which a fallen soul might come to possess it. The distinction on which the mediaeval discussion turns is already present here: secular learning proceeds from the efforts of human reason, sacred doctrine from the word of God as revealed to the faithful.

In the City of God he surveys the Greek schools and gives the Platonists the highest place, on the ground that they acknowledged an immaterial and intelligible reality and sought a good beyond the senses. Even so, the best of pagan philosophy falls short, since they knew where to look without knowing the way. Augustine is aware that St. Paul had warned the faithful to beware lest any man spoil them through philosophy and vain deceit, and he defends his praise of the Platonists by observing that the Apostle also said that what is known of God is manifest among the gentiles. If those called philosophers have said anything true and in harmony with the faith, he writes, it is to be claimed for Christian use as the spoils of the Egyptians were claimed by the Jews.

The formula that follows is that one must believe in order to understand. Reason is not set against faith but placed in its service. The philosopher who refuses to believe will not reach the highest truths, since those truths exceed the unaided intellect; the believer who refuses to think will hold the truth without comprehending it. Whether philosophy retains any autonomy under such an arrangement is a further question. Augustine holds that it can be dispensed with in all the major concerns of knowledge, love, and action, yet does not conclude that it should be discarded. The relation of the two disciplines is examined at greater length under the ideas of Theology and Religion.

The settlement leaves a pressure which later Christian writers must manage. If faith precedes rational comprehension, it may be asked whether philosophy arrives at truth on its own or only articulates what faith already possesses. Aquinas answers that philosophy has an independent reach, demonstrating certain truths, among them the existence of God, which faith also holds on other grounds. Descartes takes the tension the other way, setting faith aside and seeking a foundation reason alone can secure. Neither Tertullian's dismissal of philosophy as vain learning nor Averroes' assertion of its supremacy over religion finds support in Augustine, whose middle position both the later theologians and the modern rationalists move away from.

The Summa Theologica opens with the question whether, besides the philosophical sciences, any further doctrine is required. Aquinas answers that it is, since certain truths necessary for salvation exceed the reach of natural reason, and since even those truths about God which reason can investigate would otherwise be known only by a few, after a long time, and with an admixture of many errors. The answer fixes the boundaries of philosophy rather than diminishing it. Philosophy proceeds from principles known by the natural light of reason, sacred theology from principles held on the authority of divine revelation. Each is a science in the strict sense, and they differ in the source of their principles rather than in the rigor with which conclusions follow.

The distinction permits a use of Aristotle which Augustine could hardly have contemplated. Aristotelian metaphysics, logic, and natural philosophy become instruments for articulating Christian doctrine without being absorbed into it, and Aquinas thinks so highly of the demonstrations that he refers to their author simply as the philosopher. The existence of God can be shown by the five ways, which are philosophical arguments, while the Trinity and the Incarnation remain accessible only through faith. There is no reason, he writes, why things treated by the philosophical sciences under the light of natural reason may not also be treated by another science under the light of revelation. Since a truth cannot conflict with a truth, no conflict between the two disciplines is possible, however much particular philosophers and theologians may disagree.

Aquinas also defends philosophy against those who dismiss it as pagan distraction, a position taken in his own tradition by Peter Damian and Bernard of Clairvaux, and in the Arabic tradition by Al-Ghazzali. Grace does not destroy nature but perfects it, and the philosopher who reasons well about causes, substances, and the virtues is doing intellectual work of his own whether or not he has received the Gospel. The error lies not in philosophizing but in supposing philosophy sufficient by itself for the highest questions, which is the position Averroes advances in answering Al-Ghazzali. On the divisions of the sciences Aquinas follows the Aristotelian ordering of the speculative and the practical, treated at greater length under the ideas of Metaphysics and Prudence.

The settlement protects philosophy by giving it a domain of its own, yet it leaves open what is to be done when philosophy, following its own methods, arrives at conclusions which cannot be reconciled with revealed doctrine. The modern answers move in two directions. Descartes makes philosophy wholly independent of theology; Bacon leaves matters of faith to divinity while freeing natural inquiry from the metaphysics that had governed it. Both accept the claim that reason has an integrity of its own, and both decline the further claim that theology stands above it. Locke, and afterward Hegel, continue the dispute on much the same ground.

Surveying the state of learning, Bacon finds it distempered in three ways: by contentious learning, which is the endless disputation of the Schoolmen; by delicate learning, which is the ornamental rhetoric of the humanists; and by fantastical learning, which is superstition. The common defect is that all three yield words rather than works. Aristotelian philosophy, in his judgment, has decayed into a system of verbal distinctions which never touches nature, and the syllogism, whatever its use in ordering what is already known, discovers nothing new. The remedy he proposes is a reformation of method rather than an abandonment of philosophy, and it belongs with the other methodological reforms of the period which are discussed under the ideas of Logic and Science.

The new method begins from systematic observation and experiment and proceeds by induction from particulars to axioms of increasing generality. The philosopher is neither a spider spinning webs out of his own substance nor an ant heaping up undigested observations, but a bee, which gathers from the world and transforms what it gathers. Such work requires patience and the deliberate correction of the idols which distort human judgment: those of the tribe, the cave, the marketplace, and the theater. Bacon divides the sciences into theology and philosophy, and philosophy into natural, human, and civil, assigning psychology, logic, and ethics to the second and politics and jurisprudence to the third.

Within natural philosophy he distinguishes two speculative branches, physics and metaphysics, from two practical ones, mechanics and magic. His use of the word practical differs from Aristotle's. It means the production of effects following upon knowledge of causes, so that his practical sciences correspond to what Aristotle calls the productive arts rather than to the sphere of choice and conduct. Knowledge and human power, Bacon holds, are the same thing, since ignorance of the cause frustrates the effect. He does not reject theoretical knowledge, but he requires that true theory prove itself in real effects, and he judges a philosophy which cannot relieve the human condition to have failed its office.

Bacon's insistence that genuine knowledge gives power over nature and generates productions tells against any part of traditional philosophy which cannot meet that test, and in this respect his reform anticipates the later separation of science from philosophy. On the relation of philosophy to theology he stands nearer to the mediaeval theologians than to Descartes or Spinoza, since he leaves matters of faith to divinity. Hume carries the demand for experimental reasoning further, and the question of whether philosophy must be measured by its productions is taken up again under the ideas of Art and Progress.

Descartes proposes to set aside every inherited opinion and to raise the whole of knowledge again from a single point of certainty. In the Discourse on the Method he recounts his dissatisfaction with the philosophy taught in the schools: the disciplines disagreed with one another, none could claim certainty, and the most celebrated doctrines rested upon the authority of ancient texts rather than upon evident truths. He resolves accordingly to accept nothing as true which he does not perceive clearly and distinctly, to divide each difficulty into its smallest parts, to proceed in order from the simple to the complex, and to review the whole so that nothing is omitted.

The Meditations carry out this program by the method of doubt. Descartes supposes that the senses deceive, that he may be dreaming, and that a malicious demon may be fabricating his entire experience. Under this pressure everything external falls away, but the act of doubting does not, since to doubt is to think and to think is to exist. The proposition is offered as an intuition rather than as the conclusion of a syllogism, and from it Descartes reconstructs the existence of God, the reliability of clear and distinct perception, and the truths of mathematics and physics.

He uses the words science and philosophy interchangeably, and describes philosophy as a whole under the figure of a tree whose roots are metaphysics, whose trunk is physics, and whose branches are the remaining sciences, reducing to medicine, mechanics, and morals. The order of that tree indicates what the method requires: the practical disciplines are to grow out of a physics which itself grows out of a metaphysics established beyond doubt. Philosophy so conceived becomes autonomous in a new sense, owing nothing to theology, to the ancients, or to common opinion, and standing or falling by the clarity of its own first principles.

With Descartes, and afterward with Spinoza, Kant, and Hegel, the modern tendency is to insist upon the complete autonomy of philosophy, in contrast with the subordination to theology which Bacon and Locke retain. The move has a consequence which the later tradition works out. Once the knowing self is taken as the starting point, the existence of anything beyond it stands most in need of proof. Hume concludes that the proof cannot be given and that philosophy should confine itself to experience; Kant takes the difficulty as the occasion for a critical examination of reason itself. The relation of the thinking self to the extended world is pursued further under the ideas of Mind and Soul.

Hume distinguishes two species of philosophy. The easy sort considers man as an active creature born for society and aims to influence conduct by eloquence and common sense; the abstruse sort considers him as a thinking creature and seeks the principles which govern the understanding. Hume recommends a union of the two, in which reasoning is rigorous yet answerable to experience and to the conduct of life. The word philosophy still carries for him the general sense it had in antiquity, covering the experimental study of natural phenomena as well as mathematics and psychology, but excluding divinity, whose foundation is faith and revelation, and excluding also inquiries into particular facts such as history, chronology, geography, and astronomy.

The result of his own inquiry is a severe restriction of what remains. Every legitimate idea is a copy of some impression, and an idea which cannot be traced to a sensory impression has no meaning. By this standard much of traditional metaphysics is set aside at once: substance, the soul, necessary connection, and the self considered as a unified thing are none of them found in experience. Causation, upon which all reasoning about matters of fact depends, proves to rest on custom rather than demonstration. We observe constant conjunction, feel an expectation arise, and call the expectation necessity; reason alone cannot justify the inference from past to future.

Hume does not leave the field empty. He recommends a modest and empirical philosophy which examines the operations of the mind with the care Newton brought to the study of nature, maps the principles of the understanding, acknowledges its limits, and declines to pronounce upon questions it cannot settle. What such a philosophy offers is not a system of the universe but a release from superstition, dogmatism, and false certainty. Whether the demand for experimental reasoning about all matters of fact leaves room for any philosophy of nature at all is a question examined under the ideas of Science and Physics.

The Humean restriction draws a sharper line than any before it between what philosophy may claim to know and what it merely speculates about, and it tends, like Bacon's insistence on productions, to reserve the status of knowledge for mathematics and the empirical sciences while reducing philosophical speculation to opinion. Kant reports that it woke him from his dogmatic slumber, and the whole of the critical philosophy may be read as an attempt to answer it without conceding the conclusion. The question of whether anything can be known beyond what the senses deliver remains among those which each age debates anew.

Kant describes his undertaking as a revolution in philosophy comparable to the Copernican revolution in astronomy. Earlier philosophers assumed that knowledge must conform to its objects; he proposes that objects must conform to the conditions under which they can be known. Philosophy is thereby turned from the pursuit of things as they are in themselves toward an examination of the structures which the mind brings to all experience. Space, time, causality, and substance are on this account not features of reality discovered by reason but forms imposed upon the matter of sensation. The task of philosophy is to set out these forms, determine how far they legitimately extend, and expose the errors which arise when reason passes beyond them.

The Critique of Pure Reason argues that the older metaphysics fails because it applies concepts beyond the limits of possible experience. The existence of God, the immortality of the soul, and the freedom of the will are ideas which reason generates of itself and which no experience can confirm or refute. The transcendental dialectic shows that every attempt to treat them as knowledge yields antinomies, pairs of contradictory conclusions each supported by argument as good as the other. Kant is also the first among these writers to separate philosophy sharply from mathematics, criticizing those philosophers who have tried to imitate mathematical thought, and to restrict the name of philosophy to the rational or a priori sciences.

Reason is not left in ruins by these limits. Having denied knowledge of the supersensible, Kant makes room for practical faith, since the ideas of God, freedom, and immortality, though not objects of theoretical knowledge, are necessary postulates of moral reason. Philosophy accordingly divides into a metaphysic of nature and a metaphysic of morals, according as it treats what is or what ought to be, a division which follows the ancient separation of the speculative from the practical sciences. Its goal, Kant writes, is wisdom, and the path to it is science.

Among the modern reformers of philosophy Kant stands somewhat apart, since his critical method is meant to establish philosophy above the empirical sciences rather than to remodel it upon them. Yet the revolution he projects is itself motivated by a wish to secure for philosophy the stability and steady development which mathematics and the empirical sciences enjoy, and in that motive he shares the temper of the age. The requirement that philosophy first give an account of its own conditions before pronouncing upon ultimate reality is taken up afterward by German idealism and by later schools of very different temper. The comparison of philosophical with empirical inquiry is treated more fully under the idea of Science.