Thomas Reid.

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

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the evidence of reasoning. All good evi-
dence is commonly called reasonable evi-
dence, and very justly, because it ought to
govern our belief as reasonable creatures.
And, according to this meaning, I think the
evidence of sense no less reasonable than-
that of demonstration.* If Nature give
us information of things that concern us,
by other means than by reasoning, reason
itself will direct us to receive that inform-
ation with thankfulness, and to make the
best use of it.

But, when we speak of the evidence of
reasoning as a particular kind of evidence,
it means the evidence of propositions that
are inferred by reasoning, from propositions
already known and believed. Thus, the
evidence of the fifth proposition of the
first book of Euclid's Elements consists in
this, That it is shewn to be the necessary
consequence of the axioms, and of the pre-
ceding propositions. In all reasoning, there
must be one or more premises, and a con-
clusion drawn from them. And the pre-
mises are called the reason why we must
believe the conclusion which we see to fol-
low from them.

That the evidence of sense is of a differ-
ent kind, needs little proof. No man seeks
a reason for believing what he sees or feels ;
and, if he did, it would be difficult to find
one. But, though he can give no reason
for believing his senses, his belief remains
as firm as if it were grounded on demon-

Many eminent philosophers, thinking it
unreasonable to believe when they could not
shew a reason, have laboured to furnish us
with reasons for believing our senses ; but
their reasons are very insufficient, and
will not bear examination. Other philoso-

* Zviniv XSynv uniiTots TY,t «.lfBriirir. x^ptusi'a Tie Ul
timtixf — Ay totle. Uimrixt,, „i W t«»™ 701s S.«
yiv AayMS «AA« -rokXixl; /J.S.KU, roTr f.m/iiio!.-
[. ' TJ*urHtra /AaXXoir r, ™ Xoyoi vls-turior xtti rots
loyois- tC6Votfoloyvjfi.HK Utxtuaxri <roi s ' p*jvo^iE'vo/s.— ■
III- H atitrSvtrts cnrv.ure Jj-tl 5vi-«wv.— Id- — H.

[272, 273 |

chap, xx,]



phers have shewn very clearly the fallacy
of these reasons, and have, as they imagine,
discovered invincible reasons against this be-
lief ; but they have never been able either
to shake it in themselves, or to convince
others. [274] The statesman continues to
plod, the soldier to fight, and the merchant
to export and import, without being in the
least moved by the demonstrations that
have been offered of the non-existence of
those things about which they are so seri-
ously employed. And a man may as soon,
by reasoning, pull the moon out of her orbit,
as destroy the belief of the objects of sense.
Shall we say, then, that the evidence
of sense is the same with that of axioms,
or self-evident truths ? I answer, First,
That, all modern philosophers seem to agree
that the existence of the objects of sense
is not self-evident, because some of them
have endeavoured to prove it by subtle rea-
soning, others to refute it. Neither of
these can consider it as self-evident.

Secondly, I would observe that the word
axiom is taken by philosophers in such a
sense as that the existence of the objects
of sense cannot, with propriety, be called
an axiom. They give the name of axiom
only to self-evident truths, that are neces-
sary, and are not limited to time and place,
but must be true at all times and in all
places. The truths attested by our senses
are not of this kind ; they are contingent,
and limited to time and place.

Thus, that one is the half of two, is an
axiom. It is equally true at all times and
in all places. We perceive, by attending
to the proposition itself, that it cannot but
be true ; and, therefore, it is called an eter-
nal, necessary, and immutable truth. That
there is at present a chair on my right hand,
and another on my left, is a truth attested
by my senses ; but it is not necessary, nor
eternal, nor immutable. It may not be
true next minute ; and, therefore, to call it
an axiom would, I apprehend, be to deviate
from the common use of the Word. [275]
Thirdly, If the word axiom be put to
signify every truth which is known imme-
diately, without being deduced from any
antecedent truth, then the existence of the
objects of sense may be called an axiom ;
fur my senses give me as immediate con-
viction of what they testify, as my under-
standing gives of what is commonly called
an axiom.

There is, no doubt, an analogy between
the evidence of sense and the evidence of
testimony. Hence, we find, in all lan-
guages, the analogical expressions of the
testimony of sense, of giving credit to our
senses, and the like. But there is a real
difference between the two, as well as a
similitude. In believing upon testimony,
we rely upon the authority of a person who

testifies ; but we have no such authority for
believing our senses.

Shall we say, then, that this belief is the
inspiration of the Almighty ? I think this
may be said in a good sense ; for I take it
to be the immediate effect of our constitu-
tion, which is the work of the Almighty.
But, if inspiration be understood to imply
a persuasion of its coming from God, our
belief of the objects of sense is not inspira-
tion ; for a man would believe his senses
though he had no notion of a Deity. He
who is persuaded that he is the workman-
ship of God, and that it is a part of his
constitution to believe his senses, may
think that a good reason to confirm his
belief. But he had the belief before he could
give this or any other reason for it.

If we compare the evidence of sense with
that of memory, we find a great resem-
blance, but still some difference. I remem-
ber distinctly to have dined yesterday with
such a company. What is the meaning of
this ? It is, that I have a distinct con-
ception and firm belief of this past event ;
not by reasoning, not by testimony, but
immediately from my constitution. And I
give the name of memory to that part of
my constitution by which I have this kind
of conviction of past events. [276]

I see a chair on my right hand. What
is the meaning of this ? It is, that T have,
by my constitution, a distinct conception
and firm belief of the present existence of
the chair in such a place and in such a
position ; and I give the name of seeing to
that part of my constitution by which I
have this immediate conviction. The two
operations agree in the immediate convic-
tion which they give. They agree in this
also, that the things believed are not
necessary, but contingent, and limited to
time and place- But they differ in two
respects : — First, That memory has some-
thing for its object that did exist in time
past ; but the object of sight, and of all the
senses, must be something which exists at
present ; — and, Secondly, That I see by my
eyes, and only when they are directed to
the object, and when it is illuminated. But
my memory is not limited by any bodily
organ that I know, nor by light and dark-
ness, though it has its limitations of another

These differences are obvious to all men,
and very reasonably lead them to consider
seeing and remembering as operations spe-
cifically different. But the nature of the
evidence they give, has a great resemblance.

* There is a more important difference than these
omitted. In memory, we cannot possibly be con-
scious or immediately cognisant of any object beyond
the modifications of the ego itself. In perception, (if
an immediate perception be allowed,) we must be
conscious, or immediately cognisant, of some php-no.
menon of the non-ego. — H.



[essay ii.

A like difference and a like resemblance
there is between the evidence of sense and
that of consciousness, which I leave the
reader to trace.

As to the opinion that evidence consists
in a perception of the agreement or dis-
agreement of ideas, we may have occasion
to consider it more particularly in another
place. Here I only observe, that, when
taken in the most favourable sense, it may
be applied with propriety to the evidence of
reasoning, and to the evidence of some
axioms. But I cannot see how, in any
sense, it can be applied to the evidence of
consciousness, to the evidence of memory,
or to that of the sentes.

When I compare the different kinds of
evidence above-mentioned, I confess, after
all, that the evidence of reasoning, and that
of some necessary and self-evident truths,
seems to be the least mysterious and the
most perfectly comprehended ; and there-
fore I do not think it strange that philoso-
phers should have endeavoured to reduce all
kinds of evidence to these. [277]

When I see a proposition to be self-evi-
dent and necessary, and that the subject is
plainly included in the predicate, there seems
to be nothing more that I can desire in order
to understand why I believe it. And when
I see a consequence that necessarily follows
from one or more self-evident propositions, I
want nothing more with regard to my belief
of that consequence. The light of truth so
fills my mind in these cases, that I can
neither conceive nor desire anything more

On the other hand, when I remember dis-
tinctly a past event, or see an object before
my eyes, this commands my belief no less
than an axiom. But when, as a philosopher,
I reflect upon this belief, and want to trace it
to its origin, I am not able to resolve it into
necessary and self-evident axioms, or con-
clusions that are necessarily consequent
upon them. I seem to want that evidence
which I can best comprehend, and which
gives perfect satisfaction to an inquisitive
mind ; yet it is ridiculous to doubt ; and I
find it is not in my power. An attempt to
throw off this belief is like an attempt to fly,
equally ridiculous and impracticable.

To a philosopher, who has been accus-
tomed to think that the treasure of his know-
ledge is the acquisition of that reasoning
power of which he boasts, it is no doubt
humiliating to find that his reason can lay no
claim to the greater part of it.

By his reason, he can discover certain
abstract and necessary relations of things ;
but his knowledge of what really exists, or
did exist, comes by another channel, which
is open to those who cannot reason. He is
led to it in the dark, and knows not how he
came by it. [278]

It is no wonder that the pride of philo-
sophy should lead some to invent vain
theories in order to account for this know-
ledge ; and others, who see this to be im-
practicable, to spurn at a knowledge they
cannot account for, and vainly attempt to
throw it off as a reproach to their under-
standing. But the wise and the humble
will receive it as the gift of Heaven, and
endeavour to make the best use of it.



Our senses may be considered in two
views: first, As they afford us agreeable
sensations, or subject us to such as are dis-
agreeable; and, secondly, As they give us
information of things that concern us.

In the first view, they neither require nor
admit of improvement. Both the painful
and the agreeable sensations of our external
senses are given by nature for certain ends ;
and they are given in that degree which is
the most proper for their end. By dimin-
ishing or increasing them, we should not
mend, but mar the woik of Nature.

Bodily pains are indications of some dis-
order or hurt of the body, and admonitions
to use the best meai.s in our power to pre-
vent or remove their causes. As far as this
can be done by temperance, exercise, regi-
men, or the skill of the physician, every man
hath sufficient inducement to do it.

When pain cannot be prevented or re-
moved, it is greatly alleviated by patience
and fortitude of mind. While the mind is
superior to pain, the man is not unhappy,
though he may be exercised. It leaves no
sting behind it, but rather matter of triumph
and agreeable reflection, when borne pro-
perly, and in a good cause. [279] The
Canadians have taught us that even savages
may acquire a superiority to the most ex-
cruciating pains ; and, in every region of
the earth, instances will be found, where a
sense of duty, of honour, or even of worldly
interest, have triumphed over it.

It is evident that nature intended for man,
in his present state, a life of labour and
toil, wherein he may be occasionally exposed
to pain and danger ; and the happiest man
is not he who has felt least of those evils,
but he -whose mind is fitted to bear them by
real magnanimity.

Our active and perceptive powers are
improved and perfected by use and exercise.
This is the constitution of nature. But,
with regard to the agreeable and disagree-
able sensations we have by our senses, the
very contrary is an established constitution
of nature — the frequent repetition of thsm
weakens their force. Sensations at first very



disagreeable, by use become tolerable, and
at last perfectly indifferent. And those that
are at first very agreeable, by frequent re-
petition become insipid, and at last, per-
haps, give disgust. Nature has set limits
to the pleasures of sense, which we cannot
pass ; and all studied gratifications of them,
as it is mean and unworthy of a man, so it
is foolish and fruitless.

The man who, in eating and drinking,
and in other gratifications of sense, obeys
the calls of Nature, without affecting deli-
cacies and refinements, has all the enjoy-
ment that the senses can afford. If one
could, by a soft and luxurious life, acquire
a more delicate sensibility to pleasure, it
must be at the expense of a like sensibility
to pain, from which he can never promise
exemption, and at the expense of cherishing
many diseases which produce pain.

The improvement of our external senses,
a^ they are the means of giving us informa-
tiijn, is a subject more worthy of our atten-
tion ; for, although they are not the noblest
and most exalted powers of our nature, yet
they are not the least useful. [280] All
that we know, or can know, of the material
world, must be grounded upon their inform-
ation ; and the philosopher, as well as the
day-labourer, must be indebted to them for
the largest part of his knowledge.

Some of our perceptions by the senses
may be called original, because they require
no previous experience or learning ; but
the far greatest part is acquired, and the
fruit of experience.

Three of our senses — to wit, smell, taste,
and hearing — originally give us only certain
sensations, and a conviction that these sensa-
tions are occasioned by some external object.
We give a name to that quality of the ob-
ject by which it is fitted to produce such a
sensation, and connect that quality with the
object, and with its other qualities.

Thus we learn, that a certain sensation
of smell is produced by a rose ; and that
quality in the rose, by which it is fitted to
produce this sensation, we call the smell of
the rose. Here it is evident that the sensa-
tion is original. The perception that the
rose has that quality which we call its
smell, is acquired. In like manner, we
learn all those qualities in bodies which we
call their smell, their taste, their sound.
These are all secondary qualities, and we
give the same name to them which we give
to the sensations they produce ; not from
any similitude between the sensation and
the quality of the same name, but because
the quality is signified to us by the sensation
as its sign, and because our senses give us
no other knowledge of the quality but that
it is fit to produce such a sensation.

By the other two senses, we have much
more ample information. By sight, we


learn to distinguish objects by their colour,
in the same manner as by their sound,
taste, and smell. By this sense, we perceive
visible objects to have extension in two
dimensions, to have visible figure and
magnitude, and a certain angular distance
from one another. These, I conceive, are
the original perceptions of sight.* [281]

By touch, we not only perceive the tem-
perature of bodies as to heat and cold,-f-
which are secondary qualities, but we per-
ceive originally their three dimensions, their
tangible figure and magnitude, their linear
distance from one another, their hardness,
softness, or fluidity. These qualities we
originally perceive by touch only ; but, by
experience, we learn to perceive all or most
of them by sight.

We learn to perceive, by one sense, what
originally could have been perceived only
by another, by finding a connection betweeD
the objects of the different senses. Hence
the original perceptions, or the sensations
of one sense become signs of whatever has
always been found connected with them ;
and from the sign, the mind passes imme-
diately to the conception and belief of the
thing signified. And, although the connec-
tion in the mind between the sign and the
thing signified by it, be the effect of custom,
this custom becomes a second nature, and
it is difficult to distinguish it from the ori-
ginal power of perception.

Thus, if a. sphere of one uniform colour
be set before nie, I perceive evidently by my
eye its figure and its three dimen-
sions. All the world will acknowledge
that, by sight only, without touching it, I
may be certain that it is a sphere ; yet it
is no less certain that, by the original power
of sight, I could not perceive it to be a
sphere, and to have three dimensions. The
eye originally could only perceive two di-
mensions, and a gradual variation of colour
on the different sides of the object.

It is experience that teaches me that the
variation of colour is an effect of spherical
convexity, and of the distribution of 1 ght
and shade. But so rapid is the progress of
the thought, from the effect to the cause,
that we attend only to the last, and can
hardly be persuaded that we do not imme-
diately see the three dimensions of the
sphere. [282]

Nay, it may be observed, that, in this
case, thu acquired perception in a manner
effaces the original one ; for the sphere is
seen to be of one uniform colour, though
originally there would have appeared a
gradual variation of colour. But that ap-

* See above, p. 123, col. b, note |, and p. 195, col. a,
note *.

1 Whether heat, cold, &c, be objects of touch,or
of a different sense, it is not here the place toiDquhe
— H.



Qessav II.

parent variation we learn to interpret as
the effect of light and shade falling upon a
sphere of one uniform colour.

A sphere may be painted upon a plane,
so exactly, as to be taken for a real sphere
when the eye is at a proper distance and
in the proper point of view. We say in
this ease, that the eye is deceived, that the
appearance is fallacious. But there is no
fallacy in the original perception, but only
in that which is acquired by custom. The
variation of colour, exhibited to the eye by
the painter's art, is the same which nature
exhibits by the different degrees of light
fulling upon the convex surface of a sphere.

In perception, whether original or ac-
quired, there is something which may be
called the sign, and something which is
signified to us, or brought to our knowledge
by that sign.

In original perception, the signs are the
various sensations which are produced by
the impressions made upon our organs. The
things signified, are the objects perceived
in consequence of those sensations, by the
original constitution of our nature.

Thus, when I grasp an ivory ball in my
hand, I have a certain sensation of touch.
Although this sensation be in the mind and
have no similitude to anything material,
yet, by the laws of my constitution, it is
immediately followed by the conception
and belief, that there is in my hand a hard
smooth body of a spherical figure, and about
an inch and a half in diameter. This belief
is grounded neither upon reasoning, nor
upon experience ; it is the immediate effect
of my constitution, and this I call original
perception. * [283]

In acquired perception, the sign may be
either a sensation, or something originally
perceived. The thing signified, is something
which, by experience, has been found con-
nected with that sign.

Thus, when the ivory ball is placed be-
fore my eye, I perceive by sight what I
before perceived by touch, that the ball is
smooth, spherical, of such a diameter, and
at such a distance from the eye ; and to
this is added the perception of its colour.
All these things I perceive by sight, dis-
tinctly and with certainty. Yet it is cer-
tain from principles of philosophy, that, if I
had not been accustomed to compare the
informations of 3ight with those of touch,
I should not have perceived these things
by sight. I should have perceived a circu-
lar object, having its colour gradually more
faint towards the shaded side. But I should
not have perceived it to have three dimen-
sions, to be spherical, to be of such a linear
magnitude, and at such a distance from the
eye. That these last mentioned are not

* See above, y. ill, a-alibi— H.

original perceptions of sight, but acquired
by experience, is sufficiently evident from
the principles of optics, and from the art of
painters, in painting objects of three dimen-
sions, upon a plane which has only two.
And it has been put beyond all doubt, by
observations recorded of several persons,
who having, by cataracts in their eyes,
been deprived of sight from their infancy,
have been couched and made to see, after
they came to years of understanding.*

Those who have had their eyesight from
infancy, acquire such perceptions so early
that they cannot recollect the time when
they had them not, and therefore make no
distinction between them and their original
perceptions ; nor can they be easily per-
suaded that there is any just foundation
for such a distinction. [284] In all lan-
guages men speak with equal assurance of
then 1 seeing objects to be spherical or cubi-
cal, as of their feeling them to be so ; nor
do they ever dream that these perceptions
of sight were not as early and original as
the perceptions they have of the same ob-
jects by touch.

This power which we acquire of perceiv-
ing things by our senses, which originally
we should not have perceived, is not the
effect of any reasoning on our part : it is
the result of our constitution, and of the
situations in which we happen to be placed.

We are so made that, when two things
are found to be conjoined in certain circum-
stances, we are prone to believe that they
are connected by nature, and will always be
found together in like circumstances. The
belief which we are led into in such cases is
not the effect of reasoning, nor does it arise
from intuitive evidence in the thing believed ;
it is, as I apprehend, the immediate effect of
our constitution. Accordingly, it is strongest
in infancy, before our reasoning power
appears — before we are capable of draw-
ing a conclusion from premises. A child
who has once burnt his finger in a candle,
from that single instance connects the pain
of burning with putting his finger in the
candle, and believes that these two things
must go together. It is obvious that this
part of our constitution is of very great use
before we come to the use of reason, and
guards'us from a thousand mischiefs, which,
without it, we would rush into ; it may
sometimes lead us into error, but the good
effects of it far overbalance the ill.

It is, no doubt, the perfection of a rational
being to have no belief but what is grounded
on intuitive evidence, or on just reasoning :
but man, I apprehend, is not such a being ;
nor is it the intention of nature that he
should be such a being, in every period of
his existence. We come into the world

* Sec? above, p. 136, note t, and p. 182, note *.— H.
['283, 28 1 j



without the exercise of reason ; we are
merely animal before we are rational crea-
tures ; and it is necessary for our preserva-
tion, that we should believe many things be-
fore we can reason. How then is our belief
to be regulated before we have reason to
regulate it? [285] Has nature left it to be
regulated by chance ? By no means. It is
regulated by certain principles, which are
parts of our constitution ; whether they
ought to be called animal principles, or in-
stinctive principles, or what name we give
to them, is of small moment ; but they are
certainly different from the faculty of rea-

Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 75 of 114)