Thomas Reid.

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

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artificial signs, they will do it, as far as
possible, by natural ones : and he that
understands perfectly the use of natural
signs, must be the best judge in all the ex-
pressive arts.



Section I.


Th e senses which we have hitherto con-
sidered, are very simple and uniform, each
of them exhibiting only one kind of sensa-
tion, and thereby indicating only one quality
of bodies. By the ear we perceive sounds,
and nothing else; by the palate, tastes;
and by the nose, odours. These qualities
are all likewise of one order, being all
secondary qualities ; whereas, by touch we
perceive not one quality only, but many,
and those of very different kinds.* The
chief of them are heat and cold, hardness
and softness, roughness and smoothness,
figure, solidity, motion, and extension.
We shall consider these in order.

As to heat and cold, it will easily be
allowed that they are secondary qualities,
of the same order with smell, taste, and
sound. And, therefore, what hath been
already said of smell, is easily applicable to
them ; that is, that the words heat and cold
have each of them two significations ; they
sometimes signify certain sensations of the
mind, which can have no existence when
when they are not felt, nor can exist any-
where but in a mind or sentient being ; but
more frequently they signify a quality in
bodies, which, by the laws of nature, occa-
sions the sensations of heat and cold in us —
a quality which, though connected by cus-
tom so closely with the sensation, that we
cannot, without difficulty, separate them,
yet hath not the least resemblance to it,

* It has been very commonly held by philosophers,
hoth in ancient and modern times, that the division
of the senses into five, is altogether inadequate ; and
psychologists, though not at one in regard to the dis-
tribution, are now generally agreed, that under Touch
—or Feeling, in thestrictest signification of the term
— are comprised perceptions which are, at least, as
well entitled to be opposed in species, as those of Taste
and Smell — II.

and may continue to exist when there is no
sensation at all.

The sensations of heat and cold are per-
fectly known ; for they neither are, nor can
be, anything else than what we feel them
to be ; but the qualities in bodies which we
call heat and cold, are unknown. They are
only conceived by us, as unknown causes or
occasions of the sensations to which we give
the same names. But, though common
sense says nothing of the nature of these
qualities, it plainly dictates the existence of
them ; and to deny that there can be heat
and cold when they are not felt, is an ab-
surdity too gross to merit confutation. For
what could be more absurd, than to say,
that the thermometer cannot rise or fall,
unless some person be present, or that the
coast of Guinea would be as cold as Nova
Zeinbla, if it had no inhabitants ?

It is the business of philosophers to in-
vestigate, by proper experiments and in-
duction, what heat and cold are in bodies.
And whether they make heat a particular
element diffused through nature, and ac-
cumulated in the heated body, or whether
they make it a certain vibration of the
parts of the heated body ; whether they de-
termine that heat and cold are contrary
qualities, as the sensations undoubtedly are
contrary, or that heat only is a quality,
and cold its privation : these questions are
within the province of philosophy ; for com-
mon sense says nothing on the one side or
the other.

But, whatever be the nature of that
quality in bodies which we call heat, we
certainly know this, that it cannot in the
least resemble the sensation of heat. It is
no less absurd to suppose a likeness be-
tween the sensation and the quality, than
it would be to suppose that the pain of
the gout resembles a square or a triangle.
The simplest man that hath common sense,
does not imagine the sensation of heat, or
anything that resembles that sensation, to
be in the fire. He only imagines that
there is something in the fire which makes
him and other sentient beings feel heat.
Yet, as the name of heat, in common lan-
guage, more frequently and more properly
signifies this unknown something in the
fire, than the sensation occasioned by it,
he justly laughs at the philosopher who
denies that there is any heat in the fire,
and thinks that he speaks contrary to com-
mon sense.

Section jl


Let us next consider hardness and soft-
ness ; by which words we always under-



stand real properties or qualities of bodies
of which we have a distinct conception.

When the parts of a body adhere so firmly
that it cannot easily be made to change its
figure, we call it hard ; when its parts are
easily displaced, we call it soft. This is the
notion which all mankind have of hardness
and softness ; they are neither sensations,
nor like any sensation ; they were real
qualities before they were perceived by
touch, and continue to be so when they are
not perceived ; for if any man will affirm
that diamonds were not hard till they were
handled, who would reason with him ?

There is, no doubt, a sensation by which
we perceive a body to be hard or soft. This
sensation of hardness may easily be had, by
pressing one's hand against the table, and
attending to the feeling that ensues, setting
aside, as much as possible, all thought of the
table and its qualities, or of any external
thing. But it is one thing to have the sens-
ation, and another to attend to it, and make
it a distinct object of reflection. The first
is very easy ; the last, in most cases, ex-
tremely difficult.

We are so accustomed to use the sensa-
tion as a sign, and to pass immediately to the
hardness signified, that, as far as appears, it
was never made an object of thought, either
by the vulgar or by philosophers ; nor has it a
name in any language. There is no sensation
more distinct, or more frequent ; yet it is
never attended to, but passes through the
mind instantaneously, and serves only to
introduce that quality in bodies, which, by a
law of our constitution, it suggests.

There are, indeed, some cases, wherein
it is no difficult matter to attend to the sens-
ation occasioned by the hardness of a body;
for instance, when it is so violent as to occa-
sion considerable pain : then nature calls
upon us to attend to it, and then we acknow-
ledge that it is a mere sensation, and can
only be in a sentient being. If a man runs
his head with violence against a pillar, I
appeal to him whether the pain he feels re-
sembles the hardness of the stone, or if he
can conceive anything like what he feels to
be in an inanimate piece of matter.

The attention of the mind is here entirely
turned towards the painful feeling ; and, to
speak in the common language of mankind,
he feels nothing in the stone, but feels a
violent pain in his head. It is quite other-
wise when he leans his head gently against
the pillar ; for then he will tell you that he
feels nothing in his head, but feels hardness
in the stone. Hath he not a sensation in
this case as well as in the other ? Un-
doubtedly he hath ; but it is a sensation
which nature intended only as a sign of
something in the stone ; and, accordingly,
he instantly fixes his attention upon the
hing signified ; and cannot, without grat

difficulty, attend so much to the sensation
as to be persuaded that there is any such
thing distinct from the hardness it signifies. ,

But, however difficult it may be to attend
to this fugitive sensation, to stop its rapid
progress, and to disjoin it from the external
quality of hardness, in whose shadow it is
apt immediately to hide itself ; this is what
a philosopher by pains and practice must
attain, otherwise it will be impossible for
him to reason justly upon this subject, or
even to understand what is here advanced.
For the hist appeal, in subjects of this na-
ture, must be to what a man feels and per-
ceives in his own mind. »

It is indeed strange that a sensation
which we have every time we feel a body
hard, and which, consequently, we can com-
mand as often and continue as long as we
please, a sensation as distinct and determi-
nate as any other, should yet be so much
unknown as never to have been made an
object of thought and reflection, nor to
have been honoured with a name in any
language ; that philosophers, as well as the
vulgar, should have entirely overlooked it,
or confounded it with that quality of bo-
dies which we call hanine^ r to which it
hath not the least similitude. May we not
hence conclude, that the knowledge of the
human faculties is but in its infancy ? —
that we have not yet learned to attend to
those operations of the mind, of which we
are conscious every hour of our lives ? —
that there are habits of inattention ac-
quired very early, which are as hard to be
overcome as other habits ? For I think it
is probable, that the novelty of this sensa-
tion will procure some attention to it in
children at first ; but, being in nowise inte-
resting in itself, as soon as it becomes
familiar, it is overlooked, and the attention
turned solely to that which it signifies.
Thus, when one is learning a language, ho
attends to the sounds ; but when he is mas-
ter of it, he attends only to the sense of
what he would express. If this is the case,
we must become as little children again, if
we will be philosophers ; we must over-
come this habit of inattention which has
been gathering strength ever since we
began to think — a habit, the usefulness of
which, in common life, atones for the dif-
ficulty it creates to the philosopher in dis-
covering the first principles of the human

The firm cohesion of the parts of a body, •
is no more like that sensation by which I
perceive it to be hard, than the vibration of
a sonorous body is like the sound I hear :
nor can I possibly perceive, by my reason,
any connection between the one and the
other. No man can give a reason, why the
vibration of a body might not have given
the sensation of smelling, and the effluvia



of bodies affected our hearing, if it had so
pleased our Maker. In like manner, no
man can give a reason why the sensations
of smell, or taste, or sound, might not have
indicated hardness, as well as that sensa-
tion which, by our constitution, does indi-

v cute it. Indeed, no man can conceive any
sensation to resemble any known quality of
bodies. Nor can any man shew, by any
Hood argument, that all our sensations
might not have been as they are, though no
body, nor quality of body, had ever existed.

• Here, then, is a phseiiomenon of human
nature, which comes to be resolved. Hard-
ness of bodies is a thing that we conceive
as distinctly, and believe as firmly, as any-
thing in nature. We have no way of com-
ing at this conception and belief, but by
means of a certain sensation of touch, to
which hardness hath not the least simili-
tude ; nor can we, by any rules of rea-
soning, infer the one from the other. The
question is, How we come by this conception

' and belief ?

First, as to the conception : Shall we
call it an idea of sensation, or of reflection ?
The last will not be affirmed ; and as little
can the first, unless we will call that an
idea of sensation which hath no resem-
blance to any sensation. So that the
origin of this idea of hardness, one of the
most common and most distinct we have,
is not to be found in all our systems of the
mind : not even in those which have so
copiously endeavoured to deduce all our
notions from sensation and reflection.

But, secondly, supposing we have got the
conception of hardness, how come we by
the belief of it ? Is it self-evident, from
comparing the ideas, that such a sensation
could not be felt, unless such a quality of
bodies existed ? No. Can it be proved by
probable or certain arguments ? No ; it
cannot. Have we got this belief, then, by
tradition, by education, or by experience ?
No ; it is not got in any of these ways.
Shall we then throw off this belief as hav-
ing no foundation in reason ? Alas ! it is
not in our power ; it triumphs over reason,
and laughs at all the arguments ofa philoso-
pher. Even the author of the " Treatise
of Human Nature,*' though he saw no rea-
son for this belief, but many against it, could
hardly conquer it in his speculative and
solitary moments ; at other times, he fairly
yielded to it, and confesses that he found
himself under a necessity to do so.

"' What shall we say, then, of this concep-
tion, and this belief, which are so unac-
countable and untractable ? I see nothing
left, but to conclude, that, by an original
principle of eur constitution, a certain sens-
ation of touch both suggests to the mind
the conception of hardness, and creates the
belief of it : or, in other words, that this sens-

ation is a natural tign of hardness. And
this I shall endeavour more fully to explain.

Section III.


As in artificial signs there is often
neither similitude between the sign and
thiog signified, nor any c nnection that
arises necessarily from the nature of the
things, so it is also in natural signs The
word told has no similitude to the substance
signified by it ; nor is it in its own nature
more tit to signify this than any other sub-
stance ; yet, by habit and custom, it sug-
gests this and no other. In like manner,
a sensation of touch suggests hardness,
although it hath neither similitude to hard-
ness, nor, as far as we can perceive, any
necessary connection with it. The differ-
ence betwixt these two signs lies oidy in
this — that, in the first, the suggestion is the
effect of habit and custom ; in the second,
it is not the effect of habit, but of the ori-
ginal constitution of our minds.

It appears evident from what hath been
said on the subject of language, that there
are natural signs as well as artificial ; and
particularly, that the thoughts, purposes,
and dispositions of the mind, have their
natural signs in the features of the face, the
modulation of the voice, and the motion
and attitude of the body : that, without a
natural knowledge of the connection between
these signs and the things signified by them,
language could never have been invented
and established among men : and, that the
fine arts are all founded upon this connec-
tion, which we may call the natural lani/nmin
of mankind. It is now proper to observe,
that there are different orders of natural
signs, and to point out the different classes
into which they may be distinguished, that
we may more distinctly conceive the rela-
tion between our sensations and the things
they suggest, and what we mean by calling
sensations signs of external things.

The first class of natural signs compre-
hends those whose connection with the
thing signified is established by nature, but
discovered only by experience. The whole i
of genuine philosophy consists in discover-
ing such connections, and reducing them
to general rules. The great Lord Verulam
had a perfect comprehension of this, when
he called it an intt revelation of jiatur \ No
man ever more distinctly understood or
happily expressed the nature and founda-
tion of the philosophic art. What is all we
know of mechanics, astronomy, and optics,
but connections established by nature, and
discovered by experience or observation,
and consequences deduced from them ?

J 22


All the knowledge we have in agriculture,
gardening, chemistry, and medicine, is built
upon the same foundation. And if ever
our philosophy concerning the human mind
is carried so far aa to deserve the name of
science, which ought never to be despaired
of, it must be by observing facts, reducing
them to general rules, and drawing just con-
clusions from them. What we commonly
call natural causes might, with more pro-
priety, be called natural «?'"?>«, and what we
pall effects, the things signified. The causes
have no proper efficiency oifJasualityJasfar
as we know ; and all we can certaintyaflfirm
is, that nature hath established a constant
conjunction between them and the things
called their effects ; and hath given to man-
kind a disposition to observe those con-
nections, to confide in their continuance, and
to make use of them for the improvement
of our knowledge, and increase of our power.

A second class is that wherein the con-
nection between the sign and thing signi-
fied, is not only established by nature, but
discovered to us by a natural principle,
without reasoning or experience. Of this
kind are the natural signs of human
thoughts, purposes, and desires, which
have been already mentioned as the natural
language of mankind. An infant may be
put into a fright by an angry countenance,
and soothed again by smiles and blandish-
ments. A child that has a good musical
ear, may be put to sleep or to dance, may be
made merry or sorrowful, by the modula-
tion of musical sounds. The principles of
all the fine arts, and of what we call a fine
taste, may be resolved into connections of
this kind. A fine taste may be improved
by reasoning and experience ; but if the
first principles of it were not planted in our
minds by nature, it could never be ac-
quired. Nay, we have already made it
appear, that a great part of this knowledge
which we have by nature, is lost by the
disuse of natural signs, and the substitution
of artificial in their place.

A third class of natural signs compre-
hends those which, though we never before
had any notion or conception of the thing
signified, do suggest it, or conjure it up,
as it were, by a natural kind of magic, and
at ence give us a conception and create a
belief of it. I shewed formerly, that our
sensations suggest to us a sentient being or
mind to which they belong — a being which
hath a permanent existence, although the
sensations are transient and of short dura-
tion — a being which is still the same, while
its sensations and other operations are
varied ten thousand ways — a being which
hath the same relation to all that infinite
variety of thoughts, purposes, actions,
affections, enjoyments, and sufferings, which
we are conscious of, or can remember. The

conception of a mind is neither an idea of
sensation nor of reflection : for it is neither
like any of our sensations, nor like any-
thing we are conscious of. The first con-
ception of it, as well as the belief of it, and
of the common relation it bears to all that we
are conscious of, or remember, is suggested to
every thinking being, we do not know how.

The notion of hardness in bodies, as well »
as the belief of it, are got in a similar
manner ; being, by an original principle of
our nature, annexed to that sensation
which we have when we feel a hard body. «
And so naturally and necessarily does the
sensation convey the notion and belief of
hardness, that hitherto they have been
confounded by the most acute inquirers
into the principles of human nature, al-
though they appear, upon accurate reflec-
tion, not only to be different things, but as
unlike as pain is to the point «f a sword. 1

It may be observed, that, as the first
class of natural signs I have mentioned is
the foundation of true philosophy, and the
second the foundation of the fine arts, or
of taste— so the last is the foundation of
common sense — a part of human nature
which hath never been explained.*

I take it for granted, that the notion of f
hardness, and the belief of it, is first got
by means of that particular sensation
which, as far back as we can remember,
does invariably suggest it ; and that, if we
had never had such a feeling, we should
never have had any notion of hardness. I
think it is evident, that we cannot, by
reasoning from our sensations, collect the
existence of bodies at all, far less any of
their qualities. This hath been proved by
unanswerable arguments by the Bishop of
Cloyne, and by the author of the " Treatise
of Human Nature." It appears as evi-
dent that this connection between our sens-
ations and the conception and belief of
external existences cannot bo produced by
habit, experience, education, or any prin-
ciple of human nature that hath been
admitted by philosophers. At the same
time, it is a fact that such sensations are
invariably connected with the conception
and belief of external existences. Hence,
by all rules of just reasoning, we must con-
clude, that this connection is the effect of
our constitution, and ought to be considered
as an original principle of human nature,
till we find some more general principle
into which it may be resolved. +

* See Stewart's ** Elements of the Philosophy
of the Human Mind." Vol II. , chap, i., $ 3, la>t
note.— H.

f This whole doctrine of natural s^ns, on which his
philosophy is in a great measure established, was bor-
rowed by Reid, in principle, and even in expression,
from Bprkclev. Compare " Minute Philosopher, '
Dial. IV., M 7, II, IS; " New Theory or Vision "
ijij 111, 117: "Theory of Vision Vindicated," SS 35
— 13—11.



Section IY.


Further, I observe that hardness is a
quality, of which we have as clear and
distinct a conception as of anything what-
soever. The cohesion of the parts of a
body with more or less force, is perfectly
understood, though its cause is not ; we
know what it is, as well as how it affects
the touch. It is, therefore, a quality of a
quite different order from those secondary
qualities we have already taken notice of,
whereof we know no more naturally than
that they are adapted to raise certain sens-
ations in us. If hardness were a quality
of the same kind, it would be a proper in-
quiry for philosophers, what hardness in
bodies is ? and we should have had various
hypotheses about it, as well as about co-
lour and heat. But it is evident that any
such hypothesis would be ridiculous. If
any man should say, that hardness in bo-
dies is a certain vibration of their parts, or
that it is certain effluvia emitted by them
which affect our touch in the manner we
feel — such hypotheses would shock com-
mon sense ; because we all know that, if
the parts of a body adhere strongly, it is
hard, although it should neither emit efflu-
via nor vibrate. Yet, at the same time,
no man can say, but that effluvia, or the
vibration of the parts of a body, might
have affected our touch, in the same man-
ner that hardness now does, if it had so
pleased the Author of our nature ; and, if
either of these hypotheses is applied to ex-
plain a secondary quality — such as smell,
or taste, or sound, or colour, or heat — there
appears no manifest absurdity in the sup-

The distinction betwixt primary and se-
condary qualities hath had several revolu-
tions. Democritus and Epicurus, and their
followers, maintained it. Aristotle and the
Peripatetics abolished it. Des Cartes,
Malebranche, and Locke, revived it, and
were thought to have put it in a very clear
light. But Bishop Berkeley again dis-
carded this distinction, by such proofs as
must be convincing to those that hold
the received doctrine of ideas.* Yet,
after all, there appears to be a real found-
ation for it in the principles of our na-

What hath been said of hardness, is so
easily applicable, not only to its opposite,
softness, but likewise to roughness and

• On this distinction of Primary and Secondary
Qualities, see " Essays on the lutel'ectual Powers,"
E.say II., chap. 17, and Mote 1), at the end uf
the volume. — It.

smoothness, to figure and motion, that we
may be excused from making the applica-
tion, which would only be a repetition of
what hath been said. All these, by means
of certain corresponding sensations of touch,
are presented to the mind as real external
qualities ; the conception and the belief of
them are invariably connected with the
corresponding sensations, by an original
principle of human nature. Their sensa-
tions have no name in any language ; they
have not only been overlooked by the vul-
gar, but by philosophers ; or, if they have
been at all taken notice of, they have been
confounded with the external qualities which
they suggest. i

Section V.


It is further to be observed, that hard-
ness and softness, roughness and smooth-
ness, figure and motion, do all suppose ex-
tension, and cannot be conceived without
it ; yet, I think it must, on the other hand,

Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 28 of 114)