Thomas Reid.

The works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters online

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putting a stop to the progress of knowledge,
by filling men with a conceit that they
knew everything. [128] It was very fruitful
also in controversies ; but, for the most part,
they were controversies about words, or
about things of no moment, or things above
the reach of the human faculties. And the
issue of them was what might be expected —
that the contending parties fought, without
gaining or losing an inch of ground, till they
were weary of the dispute, or their atten-
tion was called off to some other subject.*

Such was the philosophy of the schools of
Europe, during many ages of darkness and
barbarism that succeeded the decline of the
Roman empire; so that there was great
need of a reformation in philosophy as well
as in religion. The light began to dawn at
last ; a spirit of inquiry sprang up, and
men got the courage to doubt of the dogmas
of Aristotle, as well as of the decrees of
Popes. The most important step in the
reformation of religion, was to destroy
the claim of infallibility, which hindered
men from using their judgment in matters
of religion ; and the most important step in
the reformation of philosophy, was to destroy
the authority of which Aristotle had so long
had peaceable possession. The last had
been attempted by Lord Bacon and others,
with no less zeal than the first by Luther
aud Calvin.

Des Cartes knew well the defects of the
prevailing system, which had begun to lose
its authority. His genius enabled him, and
his spirit promp'ted him, to attempt a new
one. He had applied much to the mathe-
matical sciences, and had made considerable
improvement in them. He wished to in-
troduce that perspicuity and evidence into
other branches of philosophy which he
found in them.

Being sensible how apt we are to be led
astray by prejudices of education, he thought
the only way to avoid error was to resolve
to doubt of everything, and hold everything
to be uncertain, even those things which
he had been taught to hold as most certain,
until he had such clear and cogent evidence
as compelled his assent. [129]

In this state of universal doubt, that
which first appeared to him to be clear and
certain, was his own existence. Of this he
was certain, because he was conscious that he
thought, that he reasoned, and that he
doubted. He used this argument, there-
fore, to prove his own existence, Cagito,
ergo sum. This he conceived to be the first
of all truths, the foundation-stone upon
which the whole fabric of human knowledge

* This is the vulgar opinion in regard to the
scholastic philosophy. The few are, however, now
aware that the human mind, though partially, was
never more powerfully developed than during the
middle ages.— H.




is built, and on which it must rest.* And,
as Archimedes thought that, if he had one
fixed point to rest his engines upon, he
could move the earth ; so Des Cartes,
charmed with the discovery of one certain
principle, hy which he emerged from the
state of universal doubt, believed that this
principle alone would be a sufficient found-
ation on which he might build the whole
system of science. He seems, therefore, to
have taken no great trouble to examine
whether there might not be other first prin-
ciples, which, on account of their own light
and evidence, ought to be admitted by
every man of sound judgment. -j- The love
of simplicity so natural to the mind of man,
led him to apply the whole force of his mind
to raise the fabric of knowledge upon this
one principle, rather than seek a broader

Accordingly, he does not admit the evi-
dence of sense to be a first principle, as he
does that of consciousness. The argu-
ments of the ancient sceptics here occurred
to him, that our senses often deceive us,
and therefore ought never to be trusted on
their own authority : that, in sleep, we often
seem to see and hear things which we are
convinced to have had no existence. But
that which chiefly led Des Cartes to think
that he ought not to trust to his senses,
without proof of their veracity, was, that he
took it for granted, as all philosophers had
done before him, that he did not perceive
external objects themselves, but certain
images of them in his own mind, called
ideas. He was certain, by consciousness,
that he had the ideas of sun and moon,
earth and sea ; but how could he be assured
that there really existed external objects
like to these ideas ?% [130]

Hitherto he was uncertain of everything
but of his own existence, and the existence
of the operations and ideas of his own mind.
Some of his disciples, it is said, remained at
this stage of his system, and got the name
of Egoists. § They could not find evidence
in the subsequent stages of his progress.
But Des Cartes resolved not to stop here ;
he endeavoured to prove, by a new argu-
ment, drawn from his idea of a Deity, the
existence of an infinitely perfect Being, who
made him and all his faculties. From the
perfection of this Being, he inferred that he
could be no deceiver ; and therefore con-
cluded that his senses, and the other facul-
ties he found in himself, are not fallacious,

• On the Cartesian doubt, see Note R. — H.

t This cannot justly be affirmed of Des Cartes.

t On this point it is probable that Des Cartes and
Beid are at one. See Notes C and N — H.

6 I am doubtful about the existence of this sup-
posed sect of Egoists. The Chevalier Ramsay,
above a century ago, incidentally speaks of this doc
trine as an offshoot of Spinolism, and under the

but may be trusted, when a proper use is
made of them.

The system of Des Cartes is, with great
perspicuity and acuteness, explained by
himself in his writings, which ought to he
consulted by those who would understand it.
The merit of Des Cartes cannot be easily
conceived by those who have not some
notion of the Peripatetic system, in which
he was educated. To throw off the preju-
dices of education, and to create a system of
nature, totally different from that which
had subdued the understanding of mankind,
and kept it in subjection for so many cen.
turies, required an uncommon force of mind.
The world which Des Cartes exhibits to
our view, is not only in its structure very
different from that of the Peripatetics, but
is, as we may say, composed of different

In the old system, everything was, by a
kind of metaphysical sublimation, resolved
into principles so mysterious that it may be
a question whether they were words with-
out meaning, or were notions too refined for
human understanding.

All that we observe in nature is, accord-
ing to Aristotle, a constant succession of
the operations of generation and corruption,
[131 ] The principles of generation are mat-
ter and form. The principle of corruption is
privation. All natural things are produced
or generated by the union of matter and
form ; matter being, as it were, the mother,
and form the father. As to matter, or the
first matter, as it is called, it is neither
substance nor accident ; it has no quality
or property ; it is nothing actually, but
everything potentially. It has so strong
an appetite for form, that it is no sooner
divested of one form than it is clothed with
another, and is equally susceptible of all
forms successively. It has no nature, but
only the capacity of having any one.

This is the account which the Peripate-
tics give of the first matter. The other
principle of generation is form, act, perfec-
tion; for these three words signify the same
thing. But we must not conceive form to
consist in the figure, size, arrangement, or
motion of the parts of matter. These, in-
deed, are accidental forms, by which things

name of Egomisme. But Father Burner, about the
same time, and, be it noted, in a work published some
ten years before Hume's " Treatise of Human Na-
ture," talks of it, on hearsay, as the speculation of a
Scotch philosopher :— " Un ecrivain Ecossois apublie,
dit on, un ouvragepour prouverqu'il n'avoit aucune
evidence de l'existence d'aucun etre que de lui ; et
encore de lui, en tant qu' esprit; n'aiant aucune de-
monstration veritable de l'existence d'aucun corps."
—Ekmens de Metaphysique, 4 61. Now, we know
that there is no such work. I am aware, however,
that there is some discussion on this point'in the
" Memoirs de Trevoux," anno 1713, p.922 ; to which
however, I mast refer the reader, as I have not that
journal at hand —But more of this below, undei
p 187.— H.

[130, 13Q



[essay ij.

artificial are formed : but every production
of Nature has a substantial form,* which,
joined to matter, makes it to be what it is.
The substantial form is a kind of informing
soul, which gives the thing its specific na-
ture, and all its qualities, powers, and
activity. Thus the substantial form of
heavy bodies, is that which makes them
descend ; of light bodies, that which makes
them ascend. The substantial form of
gold, is that which gives it its ductility, its
fusibility, its weight, its colour, and all its
qualities ; and the same is to be understood of
every natural production. A change in the
accidental form of any body, is alteration
only ; but a change in the substantial form
is generation and corruption : it is corrup-
tion with respect to the substantial form, of
which the body is deprived ; it is genera-
tion with respect to the substantial form
that succeeds. Thus, when a horse dies
and turns to dust, the philosophical account
of the phaenomenon is this : — A certain por-
tion of the materia prima, which was joined
to the substantial form of a horse, is de-
prived of it by privation, and in the same
instant is invested with the substantial form
of earth. [132] As every substance must
have a substantial form, there are some of
those forms inanimate, some vegetative,
some animal, and some rational. The three
former kinds can only subsist in matter ;
but the last, according to the schoolmen, is
immediately created by God, and infused
into the body, making one substance with
it, while they are united; yet capable of
being disjoined from the body, and of sub-
sisting by itself.

Such are the principles of natural things in
the Peripatetic system. It retains so much
of the ancient Pythagorean doctrine, that
we cannot ascribe the invention of it solely
to Aristotle, although he, no doubt, made
considerable alterations in it. The first
matter was probably the same in both sys-
tems, and was in both held to be eternal.
They differed more about form. The Py-
thagoreans and Platonists held forms or
ideas, as they called them, to be eternal,
immutable, and self-existent. Aristotle
maintained that they were not eternal, nor
self-existent. On the other hand, he did
not allow them to be produced, but educed
from matter ; yet he held them not to be
actually in the matter from which they are
educed, but potentially only. But these
two systems differed less from one another,
than that of Des Cartes did from both.

In the world of Des Cartes we meet with
two kinds of beings only — to wit, body and
mind ; the first the object of our senses,

* It is not. however, to be supposed that the
scholastic doctrine of Substantial Forms receives any
countenance from the authority of Aristotle, if we
lav aside his language touching the soul. — H.

the other of consciousness ; both of them
things of which we have a distinct appre-
hension, if the human mind be capable of
distinct apprehension at all. To the first,
no qualities are ascribed but extension,
figure, and motion ; to the last, nothing but
thought, and its various modifications, of
which we are conscious." He could ob-
serve no common attribute, no resembling
feature, in the attributes of body and mind,
and therefore concluded them to be distinc*
substances, and totally of a different nature ;
and that body, from its very nature, is in-
animate and inert, incapable of any kind of
thought or sensation, or of producing any
change or alteration in- itself. [138]

Des Cartes must be allowed the honour
of being the first who drew a distinct line
between the material and intellectual world,
which, in all the old systems, were so
blended together that it was impossible to
say where the one ends and the other be-
gins.-)- How much this distinction hath
contributed to the improvements of modern
times, in the philosophy both of body and
of mind, is not easy to say.

One obvious consequence of this distinc-
tion was, that accurate reflection on the
operations of our own mind is the only way
to make any progress in the knowledge of
it. Malebranche, Locke, Berkeley, and
Hume, were taught this lesson by Des
Cartes ; and to it we owe their most va-
luable discoveries in this branch of philo-
sophy. The analogical way of reasoning
concerning the powers of the mind from the
properties of body, which is the source of
almost all the errors on this subject, and
which is so natural to the bulk of mankind,
was as contrary to the principles of Des
Cartes, as it was agreeable to the princi-
ples of the old philosophy. We may there-
fore truly say, that, in that part of philoso-
phy which relates to the mind, Des Cartes
laid the foundation, and put us into that
tract which all wise men now acknowledge
to be the only one in which we can expect

With regard to physics, or the philosophy
of body, if Des Cartes had not the merit of
leading men into the right tract, we must
allow him that of bringing them out of a
wrong one. The Peripatetics, by assigning
to every species of body a particular sub-
stantial form, which produces, in an un-
known manner, all the effects we observe
in it, put a stop to all improvement in this
branch of philosophy. Gravity and levity,
fluidity and hardness, heat and cold, were
qualities arising from the substantial form
of the bodies to which they belonged. Gen-

• In the Cartesian language, the term thought in-
cluded all of which we are conscious.— H.

+ This assertion is true in general ; but some in.
dividual exceptions might be taken.— H.

[ 132, 133")



eration and corruption, substantial forms
and occult qualities, were always at hand,
to resolve every phenomenon. This phi-
losophy, therefore, instead of accounting
for any of the phsenomena of Nature, con-
trived only to give learned names to their
unknown causes, and fed men with the husks
of barbarous terms, instead of the fruit of
real knowledge. [134]

By the spreading of the Cartesian system,
materia prima, substantial forms, and oc-
cult qualities, with all the jargon of the
Aristotelian physics, fell into utter disgrace,
and were never mentioned by the followers
of the new system, but as a subject of ridi-
cule. Men became sensible that their un-
derstanding had been hoodwinked by those
hard terms. They were now accustomed
to explain the phenomena of nature, by
the figure, size, and motion of the particles
of matter, things perfectly level to human
understanding, and could relish nothing in
philosophy that was dark and unintelligible.
Aristotle, after a reign of more than a
thousand years, was now exposed as an
objectof derision even to the vulgar, arrayed
in the mock majesty of his substantial forms
and occult qualities. The ladies became
fond of a philosophy which was easily learned,
and required no words too harsh for their
delicate organs. Queens and princesses,
the most distinguished personages of the
age, courted the conversation of Des Cartes,
and became adepts in his philosophy. Wit-
uess Christina, Queen of Sweden, and
Elizabeth, daughter of Frederick, King of
Bohemia, the mother of our Royal Family.
The last, though very young when Des
Cartes wrote his " Principia," he declares
to be the only person he knew, who per-
fectly understood not only all his philoso-
phical writings, but the most abstruse of
his mathematical works.

That men should rush with violence from
one extreme, without going more or less
into the contrary extreme, is not to be ex-
pected from the weakness of human nature.
Des Cartes and his followers were not ex-
empted from this weakness ; they thought
that extension, figure, and motion, were
sufficient to resolve all the phsenomena of
the material system. To admit other qua-
lities, whose cause is unknown, was to
return to Egypt, from which they had been
so happily delivered. [135]

When Sir Isaac Newton's doctrine of
gravitation was published, the great objec-
tion to it, which hindered its general recep-
tion in Europe for half a century, was, that
gravitation seemed to be an occult quality,
as it could not be accounted for by exten-
sion, figure, and motion, the known attri-
butes of body. They who defended him
found it difficult to answer this objection to
the satisfaction of those who had been

initiated in the principles of the Cartesian
system. But, by degrees, men came to
be sensible that, in revolting from Ari-
stotle, the Cartesians had gone into the oppo-
site extreme ; experience convinced them
that there are qualities in the material
world, whose existence is certain though
their cause be occult. To acknowledge this,
is only a candid confession of human ignor-
ance, than which there is nothing more be-
coming a philosopher.

As all that we can know of the mind must
be derived from a careful observation of its
operations in ourselves ; so all that we can
know of the material system must be derived
from what can be discovered by our senses,
Des Cartes was not ignorant of this ; nor
was his system so unfriendly to observation
and experiment as the old system was.*
He made many experiments, and called
earnestly upon all lovers of truth to aid him
in this way ; but, believing that all the
phsenomena of the material world are the
result of extension, figure, and motion, and
that the Deity always combines these, so as
to produce the phsenomena in the simplest
manner possible, he thought that, from a
few experiments, he might be able to dis-
cover the simplest way in which the obvious
phsenomena of nature can be produced by
matter and motion only ; and that this must
be the way in which they are actually pro-
duced. His conjectures were ingenious, upon
the principles he had adopted ; but they are
found to be so far from the truth, that they
ought for ever to discourage philosophers
from trusting to conjecture in the operations
of nature. [136]

The vortices or whirlpools of subtile
matter by which Des Cartes endeavoured
to account for the phsenomena of the ma-
terial world, are now found to be fictions,
no less than the sensible species of Ari-
stotle, -f-

It was reserved for Sir Isaac Newton to
point out clearly the road to the knowledge
of nature's works. Taught by Lord Bacon
to despise hypotheses as the fictions of hu-
man fancy, he laid it down as a rule of
philosophising, that no causes of natural
things ought to be assigned but such as can
be proved to have a real existence. He
saw that all the length men can go in ac-
counting for phsenomena, is to discover the
laws of nature according to which they are
produced; and, therefore, that the true
method of philosophising is this : From
real facts, ascertained by observation and
experiment, to collect by just induction the

• That is, the Aristotelic. But Aristotle himself
was as declared an advocate of experiment as any
philosopher ; and it is not to be imputed to him that
his authority had subsequently the effect of imped,
ing, by being held to supersede, observation. — H.

f Read *'the sensible species of the schoolmen. *
See Note M.— H.



["essay II,

laws of Nature, and to apply the laws so
discovered, to account for the phenomena
of Nature.

Thus, the natural philosopher has the
rules of his art fixed with no less precision
than the mathematician, and may be no less
certain when he keeps within them, and
when he deviates from them. And, though
the evidence of a law of nature from induc-
tion is not demonstrative, it is the only kind
of evidence on which all the most import-
ant affairs of human life must rest.

Pursuing this road without deviation,
Newton discovered the laws of our planet-
ary system, and of the rays of light ; and
gave the first and the noblest examples of
that chaste induction which Lord Bacon
could only delineate in theory.

How strange is it that the human mind
should have wandered for so many ages,
without falling into this tract ! How much
more strange, that, after it has been clearly
discovered, and a happy progress made in it,
many choose rather to wander in the fairy
regions of hypothesis ! [137]

To return to Des Cartes's notions of the
manner of our perceiving external objects,
from which a concern to do justice to the
merit of that great reformer in philosophy
has led me to digress, he took it for granted,
as the old philosophers had done, that what
we immediately perceive must be either in
the mind itself, or in the brain, to which
the mind is immediately present. The im-
pressions made upon our organs, nerves,
and brain could be nothing, according to
his philosophy, but various modifications of
extension, figure, and motion. There could
be nothing in the brain like sound or colour,
taste or smell, heat or cold ; these are sens-
ations in the mind, which, by the laws of
the union of soul and body, are raised on
occasion of certain traces in the brain ; and
although he gives the name of ideas to those
traces in the brain, he does not think it
necessary that they should be perfectly
like to the things which they represent,
any more than that words or signs should
resemble the things they signify. But,
says he, that we may follow tne received
opinion as far as is possible, we may allow
a slight resemblance. Thus we know that
a print in a book may represent houses,
temples, and groves ; and so far is it from
being necessary that the print should be
perfectly like the thing it represents, that
its perfection often requires the contrary :
for a circle must often be represented by an
ellipse, a square by a rhombus, and so of
other things."

* But be it observed that Des Cartes did not allow.
Tar less hold, that the mind had any cognizance of
these organic motions— of these material ideas They
were merely tlie antecedents, established by the law of
union, of themental idea : which mental idea was no-

The perceptions of sense, he thought, are
to be referred solely to the union of soul
and body. They commonly exhibit to us
only what may hurt or profit our bodies ;
and rarely, and by accident only, exhibit
things as they are in themselves. It is by
observing this, that we must learn to throw
off the prejudices of sense, and to attend
with our intellect to the ideas which are by
nature implanted in it. By this means we
shall understand that the nature of matter
does not consist in those things that affect
our senses, such as colour, or smell, or taste ;
but only in this, that it is something ex-
tended in length, breadth, and depth. [138]

The writings of Des Cartes have, in ge-
neral, a remarkable degree of perspicuity ;
and he undoubtedly intended that, in this
particular, his philosophy should be a per-
fect contrast to that of Aristotle ; yet, in
what he has said, in different parts of his
writings, of our perceptions of external
objects, there seems to be some obscurity,
and even inconsistency ; whether owing to
his having had different opinions on the sub-
ject at different times, or to the difficulty he
found in it, I will not pretend to say.

There are two points, in particular,
wherein I cannot reconcile him to himself :
the first, regarding the place of the ideas
or images of external objects, which are the
immediate objects of perception ; the second.
with regard to the veracity of our external

As to the first, he sometimes places the
ideas of material objects in the brain, not
only when they are perceived, but when
they are remembered or imagined; and
this has always been held to be the Car-
tesian doctrine;* yet he sometimes says,
that we are not to conceive the images or
traces in the brain to be perceived, as if
there were eyes in the brain ; these traces
are only occasions on which, by the laws of
the union of soul and body, ideas are ex
cited in the mind ; and, therefore, it is not
necessary that there should be an exact
resemblance between the traces and the
things represented by them, any more than

Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 61 of 114)