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ARCHIBALD B. D. ALEXANDER - 1922 - Table of contents

Diccionario filosófico
Complete edition

Diccionario de Filosofía
Brief definition of the most important concepts of philosophy.


A Dictionary of English Philosophical Terms Francis Garden

Biografías y semblanzas Biographical references and lives of philosophers

Brief introduction to the thought of Ortega y Gasset

History of Philosophy Summaries

Historia de la Filosofía
Explanation of the thought of the great philosophers; summaries, exercises...

Historia de la Filosofía
Digital edition of the History of Philosophy by Jaime Balmes

Historia de la Filosofía
Digital edition of the History of Philosophy by Zeferino González

Vidas, opiniones y sentencias de los filósofos más ilustres
Complete digital edition of the work of Diogenes Laertius

Compendio de las vidas de los filósofos antiguos

A brief history of Greek Philosophy
B. C. Burt






Its origin and character


SOCRATES. Cynics and Cyrenaics



Stoicism. Epicureanism

Roman Moralists: Seneca, Epictetus, M. Aurelius
Alexandrian Mystics: Philo, Plotinus, Proclus


THE PATRISTIC PERIOD Augustine and Church Fathers

SCHOLASTIC PERIOD Nominalism and Realism

Anselm, Abelard, Peter Lombard

1. Alexander of Hales, Albertus Magnus, Thomas Aquinas
2. Duns Scotus, Francis of Assisi, William of Occam


1. Revival of Learning
2. Reformation
3. Rise of Sciences
Bruno, Böhme, Montaigne



Geulinx, Occasionalism
Malebranche, Pantheism
Spinoza, Acosmism



Development of empiricism-Berkeley
Sceptical Conclusion-Hume

Natural Philosophy
Theological Controversy
Ethical Theories
Scottish Philosophy

Earlier Rationalism
Bossuet, Fontenelle, Bayle, Montesquieu, Condillac, Helvetius
Materialistic Tendencies
Voltaire, Diderot, D'Alembert,  La Mettrie, Holbach, Rousseau


Thomasius, Tschirnhausen, Wolff

Mendelssohn, Nicolai







Hamann, Herder, Jacobi
Schiller and Humboldt

1. Science of Knowledge
2. Its Theoretic Principles
3. Its Practical Sphere

1. Philosophy of Nature
2. Philosophy of Identity
3. Mythology and Revelation

1. Novalis and Schlegel
2. Baader and Krause
3. Schleiermacher


1. Herbart
2. Beneke
3. Schopenhauer


1. Influence of Hegelianism
2. Materialistic Tendency—Haeckel
3. Idealistic Tendency
Fechner, Lotze, Hartmann, Wundt
4. Modern Psychology
5. Neo-Kantianism
Dühring, Schuppe, Ritschl
6. Eucken and Activist Tendency

1. Cousin and Eclecticism
2. Comte and Positivism
3. Religious Philosophy
4. Philosophy of Development—Taine, Renan, Fouillée

1. Utilitarianism—Bentham and Mill
2. Evolution—Darwin and Spencer. Maurice, Newman, Martineau
3. Influence of German Idealism. Caird, Green, Bradley, etc.

Pragmatism—Wm. James
Neo-Realism. Revival of Idealism in Italy. The Philosophy of the Gifford Lectures







Chap. III. Idealistic tendency. Descartes

Bacon and Descartes have often been compared, and indeed there is a certain resemblance between the two. Each regarded himself as the prophet of a new era. Each recognised the need of a new method of science. Both had unbounded belief in their own powers. "Give me space and movement," said Descartes, "and I will construct the universe." Schopenhauer has said that what Bacon did for Physics was done by Descartes for Metaphysics—viz., to begin at the beginning. Hence with Bacon Descartes shares the distinction of creating a new starting-point for philosophy. But while Bacon only proposes a novel method, Descartes propounds also an original system, from which has proceeded the most important development of modern thought. He has been called, therefore, not without justice, the father of modern philosophy.

René Descartes (1596-1650) was born at La Haye, in Touraine. On the completion of his studies, being dissatisfied with the prevalent philosophy and sceptical with regard to all truth, he took service under Moritz of Nassau I and afterwards under Tilly. After travelling for some time, he settled in Paris, and later in Holland, where, drawn to study, he wrote most of his books. At the I invitation of Queen Christina of Sweden he ultimately went to Stockholm, where he died in 1650.


Reserved by nature, Descartes lived an isolated life. He played his part, as he himself says, like a man in a mask, which implied, not indeed any conscious duplicity, but a certain apartness of mind which characterized both his life and his writings. Though his system of thought was irreconcilable with Christianity, his profession of the Catholic faith was apparently sincere. There is no evidence of the hypocrisy which Professor Mahaffy has attributed to him. His practice of religion was no outward show, but the expression of his heartfelt belief.

The interest of Descartes' life lies in the story of his mental history, of which his Meditations give us an account. His most important works are: Discourse on the Method of Rightly Conducting the Reason (1637); Meditations on First Philosophy, in which the existence of God and the distinction of mind and body are demonstrated (1641); The Principles of Philosophy (1644). The Discourse on Method has been truly named one of the epoch-making books of the world. 

If Bacon was the founder of the inductive method, Descartes may be said to be the author of the deductive. It must not, however, be understood that Descartes denied the value of observation and experience in obtaining knowledge. All that he maintained was that these of themselves were insufficient. Induction had its place, he acknowledged, in observing and collecting facts, but he demanded that the method of induction should lead to a single principle of highest and absolute certainty, from which, by a process of composition, the whole compass of experience must find its explanation.

Descartes, like Bacon, recognised the need of method if certainty of truth was to be obtained. His earliest writing, therefore, is a treatise on Method, in which, while tracing the course of his mental development, he lays down the rules by which he is resolved to guide his inquiries, and by the observance of which he hopes to gain absolute certainty: (1) Never to accept anything for true which I did not clearly know to be such; (2) to divide each of the difficulties under examination into as many parts as possible; (3) to commence with the simplest objects and ascend, step by step, to the more complex; (4) in every case to make enumerations so complete that I might be assured nothing was omitted.

The distinguishing feature of his method, therefore, is that he seeks by an inductive enumeration and critical sifting of facts to reach a single point from which he may deduce all further truths—to attain to that truth which itself, contained in no higher, affords the condition of reaching all other truths. Philosophy is, therefore, first analytic and then synthetic. These ideas or principles, which, as being self-evidencing, stand in need of no proof as their guarantee, Descartes names ultimate truths or innate ideas.

The analysis of Descartes presupposes a preliminary condition. That preliminary is doubt—which is equivalent to the absence of any decision, whether affirmative or negative, regarding the relation of the subject and the predicate of a judgment. This suspension of judgment is not an end in itself, and must be distinguished from scepticism, which is a permanent state of mind, and involves despair. It simply arises from the absence of adequate grounds to determine either affirmatively or negatively, and passes away when the mind can attain to any position of certainty.

Doubt is, therefore, the starting-point of all thought, the solvent which must be brought to bear on all our inherited beliefs and opinions bequeathed by education and authority. By this act of doubt Descartes asserted a right to decide on the truth or falsity of what authority had laid down, and therefore vindicated the superiority of another principle in the sphere of truth—viz., human thought itself, unfettered except by its own laws. If Descartes had no other distinction, he must be acknowledged as the champion of independence in the realm of thought, and the vindicator of the rights of the intellect to pursue truth untrammelled by authority. In this respect what Bacon achieved in Britain, Descartes accomplished on the Continent.

Proceeding from the principle de omnibus dubitandum the whole circuit of ideas is reviewed, and one after another is shown to be uncertain.

"All that I have hitherto accepted as possessed of the highest truth and certainty, I received either from or through the senses. But I have observed that these sometimes mislead us, and it is a part of prudence not to place absolute confidence in that by which we have even once been deceived." Descartes finds it possible to doubt the presentation of his senses, the contents of his memory, and even the demonstrations of mathematics. "I will suppose that not God, but some malignant demon, which is at once exceedingly potent and deceitful, has employed all his artifices to deceive me. I will suppose that the sky, the air, the earth, colours, figures, sounds, and all external things are nothing better than the illusions of dreams, by means of which this being has laid snares for my credulity. I will suppose all the things which I see are false. I will believe that none of those objects which my fallacious memory represents ever existed. I will suppose that I possess no senses, and that body, figure, extension, etc., are fictions of my mind. What is left? Am I, who am deceived, at least not something? Do not my very delusions involve my existence? May I not say—'I exist, since I am deceived?' Let a malignant being deceive me as he may, he cannot bring it about that I am nothing. So that it must be maintained that this proposition, I am, I exist—is necessarily true each time it is expressed by me or conceived in my mind. What I am I know not, but I am assured that I am."

Subjecting his sensations and thoughts to a rigorous examination, Descartes found that he could think away all the attributes of body and mind except one—his thinking; he could doubt all things but this—that he, the thinker, existed. In doubting, we think. But in affirming the fact of our thought, and in being necessitated to affirm it, we affirm and are compelled to affirm, the fact of self-existence. This fact, therefore, is above all proof, as it is above all doubt, and is the fundamental certainty. Cogito, ergo sum, the relation between consciousness and existence, is for Descartes the starting-point of all philosophy.

Descartes' principle of certitude has been subjected to keen and varied criticism. There is a sense, indeed, in which it may be said that the dictum is a begging of the question; he assumes at the outset the very thing he wants to prove. "When he says, 'I will question everything which I can doubt,' he virtually posits the 'I' as the umpire by whose verdict everything is to be decided." Cogito, ergo sum, is only in form a syllogism. It is not based on any higher premiss. Yet it has, in a true sense, all the validity Descartes claims for it. It is the expression of the ultimate unity of thought and being. It is the assertion of self-consciousness as the principle upon which all knowledge must rest.

This utterance of Descartes must be acknowledged as one of the great moments in the history of philosophy. Its very simplicity tends to conceal its significance. "Herewith," says Hegel, "has philosophy regained its proper ground, in that thought starts with thought as from something certain in itself; not from something external or given, not from authority, but simply from the freedom contained in 'I think.' " 

This base-rock of self-consciousness to which Descartes has got back affords at once a source and test of all further knowledge. From this primal idea of self, Descartes conceives that he can re-establish the world which doubt has destroyed. And not only does he feel that from this principle all knowledge can be developed, but by it also there is provided for him a test or criterion by which all knowledge can be evaluated. What was it that gave certitude to this truth—"I think, therefore I am"? "It is just the clearness and distinctness with which I apprehend it." Here then must be my criterion of all truth, my touch-stone of all knowledge—that only is certain which I clearly and distinctly recognise to be true—that which I feel to be as certain as the proposition, Cogito, ergo sum.

It must be admitted, however, that there is some ambiguity both with regard to the source and the test which Descartes here assumes. If self-consciousness be conceived as merely subjective and individual, as Descartes seems to have conceived it, it is difficult to see how he can ever get beyond his own individuality to the world that lies outside. He has by his own definition cut the connection between self and not-self, and henceforth there is "a great gulf fixed" which the mere subjective mind cannot bridge over. There is, indeed, a sense in which self-consciousness does imply being, in so far as subject and object are bound up with every act of thought.


It must be felt, moreover, that there is considerable ambiguity with regard to the terms "clearness and distinctness." For one thing, they are at best comparative terms, expressing merely a higher or lower degree of consciousness; and they are also subjective or relative, dependent on the consciousness of a particular individual.

Furnished with this criterion of truth, Descartes passes in review his various ideas, and is able to bring back to his possession most or many of the truths which he formerly doubted.

Among our ideas, some of which are intuitive or innate and some derived from without, we find the idea of God. Whence do we get this idea? Not from ourselves; for the imperfect cannot originate the perfect. It must, therefore, be innate, part of the original constitution of the understanding, and implanted there by a being that possesses in His own nature every perfection. If we ask further how we are capable of conceiving a nature more perfect than our own, we are driven to the answer that we must have received it from some being whose nature actually is more perfect. In other words, this idea of perfection which we find in us must have a cause, which we cannot discover in our own nature nor in that of any other finite being. For the principle of causality requires that there must be at least as much reality in the cause as there is in the effect. If, then, there exists in my mind an idea which is too great to have proceeded from my own nature or the nature of any other finite and imperfect being, then it must have come from some source which is commensurate with its greatness and perfection. In short, this idea of God, as a perfect being, could not have existed in my mind had it not been produced in me by such a being Himself.

In the formulation of this proof we are reminded of the ontological demonstration of St. Anselm, though Descartes repudiates the similarity, and indeed the arguments of the Schoolmen generally. The Cartesian proof labours under certain assumptions which beset all such attempts. For one thing, Descartes assumes without proof that the individual consciousness knows itself to be finite and imperfect, and that it also knows what perfection is. Furthermore, it contains the fallacy of arguing from the conceptual to real existence; and indeed the argument moves in a circle, for the objective reality of external things is subsequently demonstrated from the existence of God, while here the existence of God is proved from our idea of Him. In other words, Descartes seeks to deduce from consciousness a being who is to guarantee the veracity of consciousness.

Descartes' proof of the existence of God takes a second form. The very idea of perfection, he holds, involves necessary existence. Amongst the various ideas of our minds we find one, the highest of all—that of a being absolutely perfect; and we perceive that this idea, unlike others, contains in it the characteristic, not of possible, but of absolutely necessary existence. Hence we conclude that such a being must necessarily exist. Kant's well-known objection to this proof is that existence is not a reality or real predicate that can be added to the notion of a thing. Existence does not increase the comprehension of the subject. "A hundred real thalers do not in the slightest degree contain more than a hundred possible ones." Nothing more is proved, Kant maintains, than the existence of the thought of the most perfect being.

The existence of God being thus proved from the very idea of Him as one of the innate ideas implanted originally in the mind by God Himself, important results follow. At first we were compelled to doubt every seeming truth, because we knew not whether our errors arose from our own nature or by the deception of a being greater than ourselves. But now being convinced of the existence of a perfect Being, we at once ascribe to Him veracity as one of His perfections; and as it would be a contradiction of His nature as an all-wise and all-powerful Being, to will to deceive us, we conclude that what is clear and distinct to our reason must be true. For though the ability to deceive might appear as a proof of power, still the wish to deceive would be a proof of evil.

From the idea of God follows that of substance. How are we to represent God philosophically to our minds? We must think of Him as the only substance. "By substance we conceive nothing else than a thing which exists in such a way as to stand in need of nothing beyond itself in order to its existence." There can, therefore, be only one substance, and that is God. All other things can exist only by help of the concourse of God.

Hence from this idea of God as the only substance, there arises one of the most notable features of Descartes' philosophy—the sharp distinction which he draws between mind and matter. In a secondary sense mind and body may be considered as substances—the one having as its attribute, thought; the other, extension, which are their real "essences" or nature. For just as everything that can be attributed to mind implies thought, so everything that can be attributed to body presupposes extension. Furthermore, we clearly and distinctly perceive that the qualities of the one substance are wholly distinct from the qualities of the other. Thought and extension are, therefore, not only different, but mutually exclusive. This insistence on the part of Descartes on the opposition of spirit and matter has given rise to the vexed problem which has dominated modern philosophy and divided thinkers into Idealists and Empiricists—the relation of mind and matter. According to Descartes, these two being mutually exclusive, their union can only be brought about in an artificial way, by the intervention of the supreme being, the infinite substance.

Descartes' transition from God to the outer world is arbitrary and mechanical. We can understand how he is convinced of the thought-substance, for he starts with thought—his own consciousness. But if by his own showing there is no interaction of mind and body, how does the external world become known to him? His answer is that God's truthfulness is pledged for the reality of that of which we have clear and distinct ideas. We have clear and distinct ideas of the external world so long as we conceive it as simply extended matter, infinitely divisible and moved from without—so long, in short, as we conceive of it in opposition to mind. We must banish from our notion of matter all ideas of action at a distance; e.g. we must explain weight, not as a tendency to the centre of the earth or as an attraction of distant particles of matter, but simply as a consequence of the pressure of other bodies. In his physical philosophy Descartes explains everything on mechanical principles, starting from the hypothesis that a certain quantity of motion has been imparted to the material universe by God at the first—a quantity which can neither be increased nor diminished—and that space is an absolute plenum in which motion propagates itself in circles.

The reason of this mechanical explanation of the universe is that, in his view, real or substantive existence is a complete thing, a whole, that has no reference to anything else. Matter, to Descartes, is essentially dead, which has no principle of activity in it beyond the motion which it received from God at the beginning. All its energy is communicated from without. There is no room for gravitation or chemical affinity in his theory. God stands without the world, foreign to it, and unrevealed by it.

This view of the world led to the difficulty of explaining the union of body and spirit in man. The body being regarded as a mere machine, a lifeless fabric connected somehow with a reasoning soul, there can only be an artificial unity, a unity of composition which still leaves them external to each other.

All animals are conceived as machines whose motions are determined by the mechanism of the nervous system, and even in the case of man, he conceived of this mechanism as a motion of fine substances, the so-called spiritus animales, and sought the point of transition from the sensory to the nervous system in a particular part of the brain, which is not double as others are—the "pineal gland." This point of union makes a reciprocal action between mind and body possible, though for the most part their activities are entirely independent.

The world thus falls into two completely separated realms—that of bodies and that of minds. But behind this dualism, according to Descartes, there lies the conception of deity, as the one perfect substance in which both find their place and activity.

Descartes was an acute mathematician, and made several valuable contributions to mathematical science. He was the first who applied algebra to the properties of curves, and was one of the pioneers of the calculus.

To ethical philosophy he devoted only subordinate attention. It ought to be our aim to abstract ourselves as far as possible from external things and to free ourselves from all bondage to the passions. We must cease to desire the impossible. There are things within our power and things beyond our power. Let us subdue our passions. That which is within our power is virtue, which is just the harmony of reason with itself—the equanimity of the Stoics.

It will thus be seen that both in his Ethics and in his Metaphysics Descartes fails to reconcile the opposed elements of our nature, and ends in a dualism.

The weakness of Cartesianism is that the three notions, the thinking substance or spirit, the extended substance or matter, and the infinite uncreated substance or God, in whom the other two are contained—are empirically assumed. He begins by divesting the mind of all assumptions and then forthwith reaffirms them as postulates of thought, moving in a circle and making the one depend on the other, and vice versa.

Descartes fails, moreover, to reconcile the duality of mind and matter which his system exhibits. The union is an artificial one. God stands outside both created substances, and connects them only in an external and abstract fashion. On the one hand his suggestion of a mechanical interaction arising in the brain opens the door for a material explanation; and on the other, his assumption that both are elements in the infinite substance paves the way for the pantheistic conception of the universe propounded by Spinoza.

Modern philosophy. Realistic tendency. Hobbes               Modern philosophy. Pantheistic tendency. Geulinx



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