Thomas Reid.

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

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We are next to consider our notion of
Space. It may be observed that, although
space be not perceived by any of our senses
when all matter is removed, yet, when we
perceive any of the primary qualities, space
presents itself as a necessary concomitant ;-|-
for there can neither be extension nor mo-
tion, nor figure nor division, nor cohesion
of parts, without space.

There are only two of our senses by which
the notion of space enters into the mind —
to wit, touch and sight. If we suppose a
man to have neither of these senses, I do
not see how he could ever have any concep-
tion of space.* Supposing him to have
both, until he sees or feels other objects,
he can have no notion of space. It has
neither colour nor figure to make it an
object of sight : it has no tangible quality
to make it an object of touch. But other
objects of sight and touch carry the notion
of space along with them ; and not the
notion only, but the belief of it ; for a body
could not exist if there was no space to con-
tain it. It could not move if there was
no space. Its situation, its distance, and
every relation it has to other bodies, suppose

But, though the notion of space seems

* See last note.— H.
t See above, p. 12*, note f — H.
t Vide supra, p. 183, eol. b, notes*, t ; and p.
128. col. b, note*.— H.

not to enter, at first, into the mind, until it
is introduced by the proper objects of sense,
yet, being once introduced, it remains in
our conception and belief, though the objects
which introduced it be removed. We see
no absurdity in supposing a body to be an-
nihilated ; but the space that contained it
remains ; and, to suppose that annihilated,
seems to be absurd. It is so much allied
to nothing or emptiness, that it seems in-
capable of annihilation or of creation.*

Space not only retains a firm hold of our
belief, even when we suppose all the objects
that introduced it to be annihilated, but it
swells to immensity. We can set no limits
to it, either of extent or of duration. Hence
we call it immense, eternal, immovable,
and indestructible. But it is only an im-
mense, eternal, immovable, and indestruc-
tible void or emptiness. Perhaps we may
apply to it what the Peripatetics said of
their first matter, that, whatever it is, it is
potentially only, not actually. [263]

When we consider parts of space that
have measure and figure, there is nothing
we understand better, nothing about which
we can reason so clearly, and to so great
extent. Extension and figure are circum-
scribed parts of space, and are the object of
geometry, a science in which human reason
has the most ample field, and can go deeper,
and with more certainty, than in any other.
But, when we attempt to comprehend the
whole of space, and to trace it to its origin,
we lose ourselves in the search. The pro-
found speculations of ingenious men upon
this subject differ so widely as may lead
us to suspect that the line of human under-
standing is too short to reach the bottom
of it.

Bishop Berkeley, I think, was the first
who observed that the extension, figure, and
space, of which we speak in common lan-
guage, and of which geometry treats, are
originally perceived by the sense of touch
only ; but that there is a notion of exten-
sion, figure, and space, which may be got
by sight, without any aid from touch. To
distinguish these, he calls the first tangible
extension, tangible figure, and tangible
space. The last he calls visible.

As I think this distinction very import-
ant in the philosophy of our senses, I shall
adopt the names used by the inventor to
express it ; remembering what has been
already observed — that space, whether tan-
gible or visible, is not so properly an object
of sense, as a necessary concomitant of the
objects both of sight and touch.-}-

* His doctrine of space is an example of Reid's
imperfect application of the criterion of necessity.
See p. 123, note t- It seemingly required but littlt to
rise to Kant's view of the conception of space, as an
a priori or native form of thought.— H

t See above, p. 124, note f.— H.

[ 262, 263]




The reader may likewise be pleased to
attend to this, that, when I use the names of
tangible and visible space, I do not mean to
adopt Bishop Berkeley's opinion, so far as
to think that they are really different things,
and altogether unlike. I take them to be
different conceptions of the same thing ;
the one very partial, and the other more
complete ; but both distinct and just, as far
as they reach. [264]

Thus, when I see a spire at a very great
distance, it seems like the point of a bodkin ;
there appears no vane at the top, no angles.
But, when I view the same object at a small
distance, I see a huge pyramid of several
angles, with a vane on the top. Neither
of these appearances is fallacious. Each of
them is what it ought to be, and what it
must be, from such an object seen at such
different distances. These different appear-
ances of the same object may serve to illus-
trate the different conceptions of space,
according as they are drawn from the in-
formation of sight alone, or as they are
drawn from the additional information of

Our sight alone, unaided by touch, gives
a very partial notion of space, but yet a
distinct one. When it is considered accord-
ing to this partial notion, I call it visible
space. The sense of touch gives a much
more complete notion of space ; and, when
it is considered according to this notion, I
call it tangible space. Perhaps there may
be intelligent beings of a higher order, whose
conceptions of space are much more com-
plete than those we have from both senses.
Another sense added to those of sight and
touch, might, for what I know, give us con-
ceptions of space as different from those we
can now attain as tangible space is from
visible, and might resolve many knotty
points concerning it, which, from the imper-
fection of our faculties, we cannot, by any
labour, untie.

Berkeley acknowledges that there is an
exact correspondence between the visible
figure and magnitude of objects, and the
tangible ; and that every modification of
the one has a modification of the other cor-
responding. He acknowledges, likewise,
that Nature has established such a con-
nection between the visible figure and mag-
nitude of an object, and the tangible, that
we learn by experience to know the tan-
gible figure and magnitude from the visible.
And, having been accustomed to do so from
infancy, we get the habit of doing it with
such facility and quickness that we think
we see the tangible figure, magnitude, and
distance of bodies, when, in reality, we only
collect those tangible qualities from the
corresponding visible qualities, which are
natural signs of them. [265]

The correspondence and connection which


Berkeley shews to be between the visible
figure and magnitude of objects, and their
tangible figure and magnitude, is in some
respects very similar to that which we have
observed between our sensations and the
primary qualities with which they are con-
nected. No sooner is the sensation felt,
than immediately we have the conception
and belief of the corresponding quality.
We give no attention to the sensation ; it
has not a name ; and it is difficult to per-
suade us that there was any such thing.

In like manner, no sooner is the visible
figure and magnitude of an object seen, than
immediately we have the conception and
belief of the corresponding tangible figure
and magnitude. We give no attention to
the visible figure and magnitude. It is
immediately forgot, as if it had never been
perceived ; and it has no name in common
language ; and, indeed, until Berkeley
pointed it out as a subject of speculation,
and gave it a name, it had none among
philosophers, excepting in one instance,
relating to the heavenly bodies, which are
beyond the reach of touch. With regard
to them, what Berkeley calls visible magni-
tude was, by astronomers, called apparent

There is surely an apparent magnitude,
and an apparent figure of terrestrial objects,
as well as of celestial ; and this is what
Berkeley calls their visible figure and mag-
nitude. But this was never made an object
of thought among philosophers, until that
author gave it a name, and observed the
correspondence and connection between it
and tangible magnitude and figure, and how
the mind gets the habit of passing so in-
stantaneously from the visible figure as a
sign to the tangible figure as the thing
signified by it, that the first is perfectly
forgot as if it had never been perceived.

Visible figure, extension, and space, may
be made a subject of mathematical specula-
tion as well as the tangible. In the visible,
we find two dimensions only ; in the tan-
gible, three. In the one, magnitude is mea-
sured by angles ; in the other, by lines.
Every part of visible space bears some pro-
portion to the whole; but tangible space
being immense, any part of it bears no pro-
portion to the whole.

Such differences in their properties led
Bishop Berkeley to think that visible and
tangible magnitude and figure are things
totally different and dissimilar, and cannot
both belong to the same object.

And upon this dissimilitude is grounded
one of the strongest arguments by which his
system is supported. For it may be said,
if there be external objects which have a
real extension and figure, it must be either
tangible extension and figure, or visible, or




both.* The last appears absurd ; nor was
it ever maintained by any man, that the
same object has two kinds of extension and
figure totally dissimilar. There is then only
one of the two really in the object ; and the
other must be ideal. But no reason can be
assigned why the perceptions of one sense
should be real, while those of another are
only ideal ; and he who is persuaded that
the objects of sight are ideas only, has
equal reason to believe so of the objects of

This argument, however, loses all its
force, if it be true, as was formerly hinted,
that visible figure and extension are only a
partial conception, and the tangible figure
and extension a more complete conception
of that figure and extension which is really
in the object, f [267]

It has been proved very fully by Bishop
Berkeley, that sight alone, without any aid
from the informations of touch, gives us no
perception, nor even conception of the dis-
tance of any object from the eye. But he
was not aware that this very principle over-
turns the argument for his system, taken
from the difference between visible and
tangible extension and figure. For, sup-
posing external objects to exist, and to have
that tangible extension and figure which we
perceive, it follows demonstrably, from the
principle now mentioned, that their visible
extension and figure must be just what we
see it to be.

The rules of perspective, and of the pro-
jection of the sphere, which is a branch of
perspective, are demonstrable. They sup-
pose the existence of external objects, which
have a tangible extension and figure ; and,
upon that supposition, they demonstrate
what must be the visibleextension and figure
of such objects, when placed in such a posi-
tion and at such a distance.

Hence, it is evident that the visible figure
and extension of objects is so far from beiDg
incompatible with the tangible, that the first
is a necessary consequence from the last in
beings that see as we do. The correspond-
ence between them is not arbitrary, like that
between words and the thing they signify, as
Berkeley thought ; but it results necessarily
from the nature of the two senses ; and this
correspondence being always found in ex-
perience to be exactly what the rules of per-
spective shew that it ought to be if the senses
give true information, is an argument of the
truth of both.

* Orneither. And this omitted supposition is the
true. For neither sight nor touch give us fitll and
accurate information in regard to the real extension
and figure of objects. See above p. 12b", notes *;
anil p. 303, col. b, note *.— H.

t If tangible figure and extension be only " a more
complete conception," &c., it cannot be a cognition
of real figure and extension.— H.



The intention of nature in the powers
which we call the external senses, is evident.
They are intended to give us that informa-
tion of external objects which the Supreme
Being saw to be proper for us in our pre-
sent state ; and they give to all mankind
the information necessary for life, without
reasoning, without any art or investigation
on our part. [268]

The most uninstructed peasant has as
distinct a conception and as firm a belief
of the immediate objects of his senses, as
the greatest philosopher ; and with this he
rests satisfied, giving himself no concern
how he came by this conception and belief.
But the philosopher is impatient to know
how his conception of external objects, and
his belief of their existence, is produced.
This, I am afraid, is hid in impenetrable
darkness. But where there is no know-
ledge, there is the more room for conjecture,
and of this, philosophers have always been
very liberal.

The dark eave and shadows of Plato,* the
species of Aristotle,-)- the films of Epicurus,
and the ideas and impressions of modern
philosophers,^ are the productions of human
fancy, successively invented to satisfy the
eager desire of knowing how we perceive
external objects ; but they are all deficient
in the two essential characters of a true and
philosophical account of the phenomenon :
for we neither have any evidence of their
existence, nor, if they did exist, can it be
shewn how they would produce perception.

It was before observed, that there are
two ingredients in this operation of percep-
tion : Jit st, the conception or notion of the
object ; and, secondly, the belief of its pre-
sent existence. Both are unaccountable.

That we can assign no adequate cause of
our first conceptions of things, I think, is
now acknowledged by the most enlightened
philosophers. We know that such is our
constitution, that in certain circumstances
we have certain conceptions ; but how they
are produced we know no more than how
we ourselves were produced. [269]

When we have got the conception of ex-
ternal objects by our senses, we can ana-
lyse them in our thought into their sim-
ple ingredients; and we can compound
those ingredients into various new forms,
which the senses never presented. But it is

* Pee p. 262, col. b, note * H.

t See Note M.— H.

X Ky ideas, as repeatedly noticed, Reid undel
stands always certain rcprc>entative entities distinct
from the knowing mind.

[267 2691

miap xx. J




beyond the power of human imagination to
form any conception, whose simple ingre-
dients have not been furnished by nature in a
manner unaccountable to our understanding.

We have an immediate conception of the
operations of our own minds, joined with a
a belief of their existence ; and this we call
consciousness.* But this is only giving a
name to this source of our knowledge. It
is not a discovery of its cause. In like man-
ner, we have, by our external senses, a
I conception of external objects, joined with a
belief of their existence ; and this we call
perception. But this is only giving a name
to another source of our knowledge, without
discovering its cause.

We know that, when certain impressions
are made upon our organs, nerves, and
brain, certain corresponding sensations are
felt, and certain objects are both conceived
and believed to exist. But in this train
of operations nature works in the dark.
We can neither discover the cause of any
one of them, nor any necessary connection
of one with another ; and, whether they
are connected by any necessary tie, or only
conjoined in our constitution by the will of
heaven, we know not.-f

That any kind of impression upon a body
should be the efficient cause of sensation, ap-
pears very absurd. Nor can we perceive
any necessary connection between sensation
and the conception and belief of an external
object. For anything we can discover, we
might have been so framed as to have all
the sensations we now have by our senses,
without any impressions upon our organs,
and without any conception of any external
object. For anything we know, we might
have been so made as to perceive external
objects, without any impressions on bodily
organs, and without any of those sensa-
tions which invariably accompany percep-
tion in our present frame. [270]

If our conception of external objects be
unaccountable, the conviction and belief of
their existence, which we get by our senses,
is no less so.±

* Here consciousness is made to consist in concep-
tion. Hut, as Reid could hardly mean that con.
sciousness conceives (i.e., represents) the operations
about which it is conversant, and is not intuitively
cognisant of them, it would seem that he occarionally
employs conception lor knowledge. This is of im-
portance in explaining favourubly Heiri's use of the
word Conception in relation to Perception. But then,
how vague and vacillating is his language I— H.

t See p. -ibl, col. b, note *.— H.

% If an immediate knowlf due of external things —
that is, a consciousness of the qualities of the non-
ccio — be admitted, the belief of their existence follows
of course. On this supposition, therefore, such a
belief would not be unaccountable j for it would be
accounted for by the fact of the knowledge in which
it would necessarily be contained. Our belief, in this
case, of the existence of external objects, would not
Demore inexplicable than our belief that 2 + S = *.
In both cases it would be sufficient to say, we believe
because tve know; for belief is only unaccountable
when it is not the consequent or concomitant of


Belief, assent, conviction, are words
which I do not think admit of logical defin-
ition, because the operation of mind sig-
nified by them is perfectly simple, and of
its own kind. Nor do they need to be de-
fined, because they are common words, and
well understood.

Belief must have an object. For he
that believes must believe something ; and
that which he believes, is called the object
of his belief. Of this object of his belief,
he must have some conception, clear or ob-
scure ; for, although there may be the most
clear and distinct conception of an object
without any belief of its existence, there
can be no belief without conception.*

Belief is always expressed in language by
a proposition, wherein something is affirmed
or denied. This is the form of speech
which in all languages is appropriated to
that purpose, and without belief there could
be neither affirmation nor denial, nor should
we have any form of words to express
either. Belief admits of all degrees, from
the slightest suspicion to the fullest assur-
ance. These things are so evident to
every man that reflects, that it would be
abusing the reader's patience to dwell upon

I proceed to observe that there are many
operations of mind in which, when we
analyse them as far as we are able, we find
belief to be an essential ingredient. A man
cannot be conscious of his own thoughts,
without believing that he thinks. He can-
not perceive an object of sense, without be-
lieving that it exists. -f- He cannot distinctly
remember a past event, without believing
that it did exist. Belief therefore is an
ingredient in consciousness, in perception,
and in remembrance. [271]

Not only inmost of our intellectual oper-
ations, but in many of the active princi-
ples of the human mind, belief enters as an
ingredient. Joy and sorrow, hope and
fear, imply a belief of good or ill, either pre
sent or in expectation Esteem, gratitude,
pity, and resentment, imply a belief of cer-
tain qualities in their objects. In every
action that is done for an end, there must
be a belief of its tendency to that end. So
large a share has belief in our intellectual

knowledge. By this, however, I do not, of course,
mean to say that knowledge is not in itself marvel-
lous and unaccountable. This statement of Keid
again lavours the opinion that his doctrine of percep-
tion is not really immediate..— H.

* Is conception here equivalent to knowledge or to
thought f— a.

f Mr Stewart (Elem. I., ch. iii., p. 146, and Essays,
II., ch. ii., p. 79, sq.) proposes a supplement to this
doctrine of Heid, in order to explain why we believe
in the existence of the qualities of external objects
when they are not the objects of our perception.
This belief he holds to be the result of experience, in
combination with an original principle ol our consti-
tution, whereby we are detirmined to believe in the
permanence of the laws of nature.— H



[essay It.

operations, in our active principles, and in
our actions themselves, that, as faith in
tilings divine is represented as the main
spring in the life of a Christian, so belief in
general is the main spring in the life of a man.

That men often believe what there is no
just ground to believe, and thereby are led
into hurtful errors, is too evident to be
denied. And, on the other hand, that there
are just grounds of belief can as little be
doubted by any man who is not a, perfect

We give the name of evidence to what-
ever is a ground of belief. To believe with-
out evidence is a weakness which every
man is concerned to avoid, and which every
man wishes to avoid. Nor is it in a mau's
power to believe anything longer than he
thinks he has evidence.

What this evidence is, is more easily felt
than described. Those who never reflected
upon its nature, feel its influence in govern-
ing their belief. It is the business of the
logician to explain its nature, and to dis-
tinguish its various kinds and degrees ; but
every man of understanding can judge of it,
and commonly judges right, when the evi-
dence is fairly laid before him, and his
mind is free from prejudice. A man who
knows nothing of the theory of vision may
have a good eye; and a man who never
speculated about evidence in the abstract
may have a good judgment. [272]

The common occasions of life lead us to
distinguish evidence into different kinds, to
which we give names that are well under-
stood ; such as the evidence of sense, the
evidence of memory, the evidence of con-
sciousness, the evidence of testimony, the
evidence of axioms, the evidence of reason-
ing. All men of common understanding
agree that each of these kinds of evidence
may afford just ground of belief, and they
agree very generally in the circumstances
that strengthen or weaken them.

Philosophers have endeavoured, by ana-
lysing the different sorts of evidence, to
lind out some common nature wherein they
all agree, and thereby to reduce them all
to one. This was the aim of the school-
men in their intricate disputes about the
criterion of truth. Des Cartes placed this
criterion of truth in clear and distinct per-
ception, and laid it down as a maxim, that
whatever we clearly and distinctly perceive
to be true, is true ; but it is difficult to
know what he understands by clear and
distinct perception in this maxim. Mr
Locke placed it in a perception of the agree-
ment or disagreement of our ideas, which
perception is immediate in intuitive know-
ledge, and by the intervention of other ideas
in reasoning.

I confess that, although I have, as I
think, a distinct notion of the different

kinds of evidence above-mentioned, and,
perhaps, of some others, which it is unne-
cessary here to enumerate, yet I am not
able to find any common nature to which
they may all be reduced. They seem to
me to agree only in this, thai they are all
fitted by Nature to produce belief in the
human mind, some of them in the highest
degree, which we call certainty, others in
various degrees according to circumstances.

I shall take it for granted that the evi-
dence of sense, when the proper circum-
stances concur, is good evidence, and a just
ground of belief. My intention in this
place is only to compare it with the other
kinds that have been mentioned, that we
may judge whether it be reducible to any of
them, or of a nature peculiar to itself. [273]

First, It seems to be quite different from

Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 74 of 114)