Part IV. REVIVAL OF PHILOSOPHY
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);
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
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
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
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
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
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
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
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
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
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