Thomas Reid.

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

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pear through the deceitful medium of such
analogical notions and expressions. *

When we lay aside those analogies, and
reflect attentively upon our perception of
the objects of sense, we must acknowledge
that, though we are conscious of perceiving
objects, we are altogether ignorant how it
is brought about ; and know as little how
we perceive objects as how we were made.
And, if we should admit an image in the
mind, or contiguous to it, we know as
little how perception may be produced by
this image as by the most distant object.
"Why, therefore, should we be led, by a
theory which is neither grounded on evi-
dence, nor, if admitted, can explain any one
phenomenon of perception, to reject the
natural and immediate dictates of those
perceptive powers, to which, in the conduct
of life, we find a necessity of yielding im-
plicit submission ?

There remains only one other argument
that I have been able to find urged against
our perceiving external objects immediately.
It is proposed by Mr Hume, who, in the
essay already quoted, after acknowledging
that it is an universal and primary opi-
nion of all men, that we perceive external

* It is self-evident that, if a thing is to be an ob-
ject immediately known, it must be known as it
exists. Now, a body must exist in some definite
part of space — in a certain place; it cannot, there-
fore, be immediately known as existing, except it be
known in its place. But this supposes the mind to
be immediately present to it in space.— H.

objects immediately, subjoins what fol-
lows : — _

" But this universal and primary opinion
of all men is soon destroyed by the slightest
philosophy, which teaches us that nothing
can ever be present to the mind but an
image or perception ; and that the senses
are only the inlets through which these
images are received, without being ever
able to produce any immediate intercourse
between the mind and the object. The
table, which we see, seems to diminish as
we remove farther from it : but the real
table, which exists independent of us, suf-
fers no alteration. [207] It was, therefore,
nothing but its image which was present to
the mind. These are the obvious dictates of
reason ; and no man who reflects ever doubted
that the existences which we consider, when
we say this house, and that tree, are nothing
but perceptions in the mind, and fleeting
copies and representations of other exist-
ences, which remain uniform and independ-
ent. So far, then, we are necessitated, by
reasoning, to depart from the primary in-
stincts of nature, and to embrace a new
system with regard to the evidence of our

"We have here a remarkable conflict be-
tween two contradictory opinions, wherein
all mankind are engaged. On the one side
stand all the vulgar, who are unpractised in
philosophical reseaches, and guided by the
uncorrupted primary instincts of nature.
On the other side stand all the philoso-
phers, ancient and modern ; every man,
without exception, who reflects. In this
division, to my great humiliation, I find
myself classed with the vulgar.

The passage now quoted is all I have
found in Mr Hume's writings upon this
point : and, indeed, there is more reason-
ing in it than I have found in any other
author ; I shall, therefore, examine it min-

First, He tells us, that " this universal
and primary opinion of all men is soon
destroyed by the slightest philosophy, which
teaches us that nothing can ever he pre-
sent to the mind but an image or percep-

The phrase of being present to the mind
has some obscurity; but I conceive he
means being an immediate object of thought ;
an immediate object, for instance, of per-
ception, of memory, or of imagination. If
this be the meaning, (and it is the only
pertinent one I can think of,) there is no
more in this passage hut an assertion of the
proposition to be proved, and an assertion
that philosophy teaches it. If this be so,
I beg leave to dissent from philosophy till
she gives me reason for what she teaches.
[208] For, though common sense andmy
external senses demand my assent to their



dictates upon their own authority, yet phi-
losophy is not entitled to this privilege.
But, that I may not dissent from so grave
a personage without giving a reason, I give
this as the reason of my dissent : — I see
the sun when he shines ; I remember the
battle of Culloden ;* and neither of these
objects is an image or perception.

He tells us, in the next place, "That the
senses are only the inlets through which
these images are received."

I know that Aristotle and the schoolmen
taught that images or species flow from ob-
jects, and are let in by the senses, and strike
upon the mind ; but this has been so effectu-
ally refuted by Des Cartes, by Malebranchc,
and many others, that nobody now pretends
to defend it. Reasonable men consider it
as one of the most unintelligible and un-
meaning parts of the ancient system. To
what cause is it owing that modern philo-
sophers are so prone to fall back into this
hypothesis, as if they really believed it ?
FoJ, of this proneness I could give many
instances besides this of Mr Hume ; and I
take the cause to be, that images in the
mind, and images let in by the senses, are
so nearly allied, and so strictly connected,
that they must stand or fall together. The
old system consistently maintained both :
but the new system has rejected the doc-
trine of images let in by the senses, hold-
ing, nevertheless, that there are images in
the mind ; and, having made this unnatural
divorce of two doctrines which ought not
to be put asunder, that which they have
retained often leads them back involun-
tarily to that which they have rejected.

Mr Hume surely did not seriously be-
lieve that an image of sound is let in by the
ear, an image of smell by the nose, an
image of hardness and softness, of solidity
and resistance, by the touch. For, besides
the absurdity of the thing, which has often
been shewn, Mr Hume, and all modern
philosophers, maintain that the images which
are the immediate objects of perception
have no existence when they are not per-
ceived ; whereas, if they were let in by the
senses, they must be, before they are per-
ceived, and have aseparate existence. [209]

He tell us, farther, that philosophy teaches
that the senses are unable to produce any
immediate intercourse between the mind
and the object. Here, I still require the
reasons that philosophy gives for this ; for,
to my apprehension, I immediately per-
ceive external objects, and this, I conceive
is the immediate intercourse here meant.

Hitherto I see nothing that can be called

* The sun can be no immediate object of conscious-
ness in perception, but only certain rays in connec-
tion with the eye. The battle of Culloden can be no
immediate-object of consciousness in recollection, but
only a certain representation by the mind itself. — H.

an argument. Perhaps it was intended
only for illustration. The argument, the
only argument, follows : —

The table which we see, seems to dimin-
ish as we remove farther from it ; but the
real table, which exists independent of us
suffers no alteration. It was, therefore,
nothing but its image which was presented
to the mind. These are the obvious dio-
tates of reason.

To judge of the strength of this argu-
ment, it is necessary to attend to a distinc-
tion which is familiar to those who are con-
versant in the mathematical sciences — I
mean the distinction between real and ap-
parent magnitude. The real magnitude of
a line is measured by some known measure
of length — as inches, feet, or miles : the
real magnitude of a surface or solid, by
known measures of surface or of capacity.
This magnitude is an object of touch only,
and not of sight ; nor could we even have
had any conception of it, without the sense
of touch; and Bishop Berkeley, on that
account, calls it tangible magnitude*

Apparent magnitude is measured by the
angle which an object subtends at the eye.
Supposing two right lines drawn from the
eye to the extremities of the object making
an angle, of which the object is the sub-
tense, the apparent magnitude is measured
by this angle. [210] This apparent mag-
nitude is an object of sight, and not of
touch. Bishop Berkeley calls it visible

If it is asked what is the apparent mag-
nitude of the sun's diameter, the answer
is, that it is about thirty-one minutes of a
degree. But, if it is asked what is the
real magnitude of the sun's diameter, the
answer must be, so many thousand miles,
or so many diameters of the earth. From
which it is evident that real magnitude, and
apparent magnitude, are things of a different
nature, though the name of magnitude is
given to both. The first has three dimen-
sions, the last only two ; the first is mea-
sured by a line, the last by an angle.

From what has been said, it is evident
that the real magnitude of a body must
continue unchanged, while the body is
unchanged. This we grant. But is it
likewise evident, that the apparent mag-

* The doctrine of Reid — that real magnitude or
extension. is the object of touch, and of touch alone —
is altogether untenable. For, in the^r^ place, mag.
nitude appears greater or less in proportion to 'the
different size of the tactile organ in different subjects ;
thus, an apple is larger to the hand of a child than to
the hand of an adult. Touch, therefore, can, at best,
afford a knowledge of the relation of magnitudes, in
proportion to the organ of' this or that individual.
But, in the second place, even in the same individual,
the same object appears greater or less, according as
it ia touched by one part of the body or by another.
On this subject, see Weber's " Annotatione6 de
Fulsu, Resorptione, Auditu et Tactu:" Leipsic,
1834.— H

[209, 210]



[essay II.

nitude must continue the same while the
body is unchanged ? So far otherwise,
that every man who knows anything of
mathematics can easily demonstrate, that
the same individual object, remaining in
the same place, and unchanged, must neces-
sarily vary in its apparent magnitude, ac-
cording as the poiut from which it is seen
is more or less distant ; and that its appa-
rent length or breadth will be nearly in a
reciprocal proportion to the distance of the
spectator. This is as certain as the princi-
ples of geometry.*

We must likewise attend to this — that,
though the real magnitude of a body is not
originally an object of sight, but of touch,
yet we learn by experience to judge of the
real magnitude in many cases by sight.
We learn by experience to judge of the
distance of a body from the eye within cer-
tain limits ; and, from its distance and ap-
parent magnitude taken together, we learn
to judge of its real magnitude. [211]

And this kind of judgment, by being
repeated every hour and almost every
minute of our lives, becomes, when we are
grown up, so ready and so habitual, that it
very much resembles the original perceptions
of our senses, and may not improperly be
called acquiredtperception.

Whether we call it judgment or acquired
perception is a verbal difference. But it is
evident that, by means of it, we often dis-
cover by one sense things which are pro-
perly and naturally the objects of another.
Thus I can say, without impropriety, I hear
a drum, I hear a great bell, or I hear a
small bell; though it is certain that the
figure or size of the sounding body is not
originally an object of hearing. In like
manner, we learn by experience how a
body of such a real magnitude and at such
a distance appears to the eye. But neither
its real magnitude, nor its distance from
the eye, are properly objects of sight, any
more than the form of a drum or the size
of a bell, are properly objects of hearing.

If these things be considered, it will ap-
pear that Mr Hume's argument hath no
force to support his conclusion — nay, that it
leads to a contrary conclusion. The argu-
ment is this : the table we see seems to di-
minish as we remove farther from it ; that
is, its apparent magnitude is diminished;
but the real table suffers no alteration — to
wit, in its real magnitude ; therefore, it is

* The whole confusion and difficulty in this mat.
ter arises from not determining what is the true object
in visual.perception. This is not any distant thing,
but merely the rays of light in immediate relation to
the organ. We therefore.' see a different object at
every movement, by which a different complement
of rays is reflected to the eye. The things from which
these rays are reflected are not, in truth, perceived at
all ; and to conceive them as objects of perception is
therefore erroneous, and productive of error.— H.

not the real table we see. I admit both the
premises in this syllogism, but I deny the
conclusion. The syllogism has what the
logicians call two middle terms : apparent
magnitude is the middle term in the first
premise; real magnitude in the second.
Therefore, according to the rules of logic,
the conclusion is not justly drawn from the
premises ; but, laying aside the rules of
logic, let us examine it by the light of com-
mon sense.

Let us suppose, for a moment, that it is
the real table we. see : Must not this real
table seem to diminish as we remove farther
from it ? It is demonstrable that it must.
How then can this apparent diminution be an
argument that it is not the real table? [212]
When that which must happen to the real
table, as we remove farther from it, does
actually happen to the table we see, it is ab-
surd to conclude from this, that it is not the
real table we see.* It is evident, therefore,
that this ingenious author has imposed upon
himself by confounding real magnitude with
apparent magnitude, and that his argument
is a mere sophism.

I observed that Mr Hume's argument
not only has no strength to support his con-
clusion, but that it leads to the contrary con-
clusion — to wit, that it is the real table we
see ;* for this plain reason, that the table
we see has precisely that apparent magni-
tude which it is demonstrable the real table
must have when placed at that distance.

This argument is made much stronger by
considering that the real table may be placed
successively at a thousand different dis-
tances, and, in every distance, in a thousand
different positions; and it can be deter-
mined demonstratively, by the rules of
geometry and perspective, what must be its
apparent magnitude and apparent figure, in
each of those distances and positions. Let
the table be placed successively in as many
of those different distances and different po-
sitions as you will, or in them all ; open
your eyes and you shall see a table pre-
cisely of that apparent magnitude, and that
apparent figure, which the real table must
have in that distance and in that position.
Is not this a strong argument that it is the
real table you see ?*

In a word, the appearance of a visible
object is infinitely diversified, according to
its distance and position. The visible ap-
pearances are innumerable, when we con-
fine ourselves to one object, and they are
multiplied according to the variety of ob-
jects. Those appearances have been mat-
ter of speculation to ingenious men, at least
since the time of Euclid. They have ac-
counted for all this variety, on the suppo-
sition that the objects we see are external,

* See last note.— H.

[211, 212]



and not in the mind itself. [213] The rules
they have demonstrated about the various
projections of the sphere, about the appear-
ances of the planets in their progressions,
stations, and retrogradations, and all the
rules of perspective, are built on the suppo-
sition that the objects of sight are external.
They can each of them be tried in thousauds
of instances. In many arts and professions,
innumerable trials are daily made ; nor
were they ever found to fail in a single in-
stance. Shall we say that a false supposi-
tion, invented by the rude vulgar, has been
so lucky in solving an infinite number of
phenomena of nature ? This, surely, would
be a greater prodigy than philosophy ever
exhibited : add to this, that, upon the con-
trary hypothesis — to wit, that the objects of
sight are internal — no account can be given
of any one of those appearances, nor any
physical cause assigned why a visible object
should, in any one case, have one apparent
figure and magnitude rather than another.

Thus, I have considered every argument
I have found advanced to prove the exist-
ence of ideas, or images of external things,
in the mind ; and, if no better arguments can
be found, I cannot help thinking that the
whole history of philosophy has never fur-
nished an instance of an opinion so unani-
mously entertained by philosophers upon so
slight grounds.

A third reflection I would make upon
this subject is, that philosophers, notwith-
standing their unanimity as to the existence
of ideas," hardly agree in any one thing
else concerning them. If ideas be not a
mere fiction, they must be, of all objects of
human knowledge, the things we have best
access to know, and to be acquainted with ;
yet there is nothing about which men differ
so much.

Some have held them to be self-existent,
others to be in the Divine mind, others in
our own minds, and others in the brain or
sensorium. I considered the hypothesis of
images in the brain, in the fourth chapter
of this essay. As to images in the mind, if
anything more is meant by the image of an
object in the mind than the thought of that
object, I know not what it means. [214]
The distinct conception of an object may,
in a metaphorical or analogical sense, be
called an image of it in the mind. But this
image is only the conception of the object,
and not the object conceived. It is an act
of the mind, and not the object of that act.-|-

Some philosophers will have our ideas, or
a part of them, to be innate ; others will
have them all to be adventitious : some de-
rive them from the senses alone ; others
from sensation and reflection : some think

• This unanimity did. not exist.— H.
1 See Notes B and C — H.

they are fabricated by the mind itself;
others that they are produced by externa
objects ; others that they are the immediate
operation of the Deity ; others say, that
impressions are the causes of ideas, and
that the causes of impressions are unknown :
some think that we have ideas only of ma-
terial objects, but none of minds, of their
operations, or of the relations of things ;
others will have the immediate object of
every thought to be 'an idea : some think
we have abstract ideas, and that by this
chiefly we are distinguished from the brutes ;
others maintain an abstract idea to be an
absurdity, and that there can be no such
thing : with some they are the immediate ob-
jects of thought, with others the only objects.

A fourth reflection is, that ideas do not
make any of the operations of the mind to
be better understood, although it was pro-
bably with that view that they have been
hrst invented, and afterwards so generally

We are at a loss to know how we per-
ceive distant objects ; how we remember
things past ; how we imagine things that
have no existence. Ideas in the mind seem
to account for all these operations : they are
all by the means of ideas reduced to one
operation — to a kind of feeling, or imme
diate perception of things present and in
contact with the percipient ; and feeling is
an operation so familiar that we think it
needs no explication, but may serve to ex-
plain other operations. [215]

But this feeling, or immediate percep-
tion, is as difficult to be comprehended as
the things which we pretend to explain by
it. Two things may be in contact without
any feeling or perception ; there must
therefore be in the percipient a power to
feel or to perceive. How this power is pro-
duced, and how it operates, is quite beyond
the reach of our knowledge. As little can
we know whether this power must be limited
to things present, and in contact with us.
Nor can any man pretend to prove that the
Being who gave us the power to. perceive
things present, may not give us the powet
to perceive things that are distant," to re-
member things past, and to conceive things
that never existed.

Some philosophers have endeavoured to
make all our senses to be only different
modifications of touch ;-j- a theory which
serves only to confound things that are dif-
ferent, and to perplex and darken things
that are clear. The theory of ideas resembles
this, by reducing all the operations of the

* An immediate perception of things distant, is a
contradiction in terms. — H.

t It an immediate perception be supposed, it can
only be rationally supposed of objects as in contact
with the organs of sense. But, in this case, all the
senses would, as Democritus held, be, in a certain
sort, only modifications of touch.— H.



[K.'fAY II.

human understanding to the perception of
ideas in our own minds. This power of
perceiving ideas is as inexplicable as any of
the powers explained by it : and the con-
tiguity of the object contributes nothing at
all to make it better understood ; because
there appears no connection between con-
tiguity and perception, but what is grounded
on prejudices drawn from some imagined
similitude between mind and body, and
from the supposition that, in perception,
the object acts upon the mind, or the mind
upon the object. We have seen how this
theory has led philosophers to confound
those operations of mind, which experience
teaches all men to be different, and teaches
them to distinguish in common language ;
and that it has led them to invent a lan-
guage inconsistent with the principles upon
which all language is grounded.

The last reflection I shall make upon this
theory, is — that the natural and necessary
consequences of it furnish a just prejudice
against it to every man who pays a due re-
gard to the common sense of mankind. [216]

Not to mention that it led the Pytha-
goreans and Plato to imagine that we see
only the shadows of external things, and
not the things themselves,* and that it gave
rise to the Peripatetic doctrine of sensible
species, one of the greatest absurdities of
that ancient system, let us only consider the
fruits it has produced since it was new-
modelled by Des Cartes. That great re-
former in philosophy saw the absurdity of
the doctrine of ideas coming from external
objects, and refuted it effectually, after it
had been received by philosophers for'thou-
sands of years ; but he still retained ideas
in the brain and in the mind.-j- Upon this
foundation all our modern systems of the
powers of the mind are built. And the tot-
tering state of those fabrics, though built
by skilful hands, may give a strong suspicion
of the unsoundness of the foundation.

It was this theory of ideas that led Des
Cartes, and those that followed him, to think
it necessary to prove, by philosophical argu-
ments, the existence of material objects.
And who does not see that philosophy must
make a very ridiculous figure in the eyes of
sensible men, while it is employed in muster-
ing up metaphysical arguments, to prove
that there is a sun and a moon, an earth and
a sea ? Yet we find these truly great men,
Des Cartes, Malebranche, Arnauld, and
Locke, seriously employing themselves in
this argument.^

Surely their principles led them to think

* See above, p. 262, col. b. note *— .H

t See Note N.— H.

X If Rcid do not allow that we arc immediately
cognitive or conscious of 'the non-ego, his own doc.
trine of perception differs not from that of othci
philosophers in the necessity for this pioof. H

that all men, from the beginning of the
world, believed the existence of these things
upon insufficient grounds, and to think that
they would be able to place upon a more
rational foundation this universal belief of
mankind. But the misfortune is, that all
the laboured arguments they have advanced,
to prove the existence of those things we
see and feel, are mere sophisms : Not one
of them will bear examination.

I might mention several paradoxes, which
Mr Locke, though by no means fond of para-
doxes, was led into by this theory of ideas.
[217] Such as, that the secondary qualities

Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 69 of 114)