Thomas Reid.

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

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reflect upon it ; and so we come to be as
little acquainted with it as if we had never
felt it. This is the case with the sensations
of all primary qualities, when they are not
so painful or pleasant as to draw our atten-

When a man moves his hand rudely
against a pointed hard body, he feels pain,
and may easily be persuaded that this pain
is a sensation, and that there is nothing
resembling it in the hard body ; at the same
time, he perceives the body to be hard and
pointed, and he knows that these qualities
belong to the body only. In this case, it is
easy to distinguish what he feels from what
he perceives.

Let him again touch the pointed body
gently, so as to give him no pain ; and now
you can hardly persuade him that he feels
anything but the figure andhardness of the
body : so difficult it is to attend to the sens-
ations belonging to primary qualities, when
they are neither pleasant nor painful. They
carry the thought to the external object,
and immediately disappear and are forgot.
Nature intended them only as signs ; and
when they have served that purpose they

We are now to consider the opinions
both of the vulgar and of philosophers upon
this subject. [241] As to the former, it
is not to be expected that they should make
distinctions which have no connection with
the common affairs of life ; they do not,
therefore, distinguish the primary from the
secondary qualities, but speak of both as
being equally qualities of the external ob-
ject. Of the primary qualities they have a
distinct notion, as they are immediately and
distinctly, perceived by the senses ; of the
secondary, their notions, as I apprehend,
are confused and indistinct, rather than
erroneous. A secondary quality is the
unknown cause or occasion of a well-known
effect ; and the same name is common to
the cause and the effect. Now, to dis-
tinguish clearly the different ingredients of a
complex notion, and, at the same time, the
different meanings of an ambiguous word,
is the work of a philosopher ; and is not
to be expected of the vulgar, when their
occasions»do not require it,

I grant, therefore, that the notion which
the vulgar have of secondary qualities, is
indistinct and inaccurate. But there seems
to be a contradiction between the vulgar
and the philosopher upon this subject, and
each charges the other with a gross al>



|_1!SSAY II,

surdity. The vulgar say, that fire is hot,
and snow cold, and sugar sweet ; and that
to deny this is a gross absurdity, and con-
tradicts the testimony of our senses. The
philosopher says, that heat, and cold, and
sweetness, are nothing but sensations in
our minds ; and it is absurd to conceive
that these sensations are in the fire, or in
the snow, or in the sugar.

I believe this contradiction, between the
vulgar and the philosopher, is more apparent
than real ; and that it is owing to an abuse
of language on the part of the philosopher,
and to indistinct notions on the part of the
vulgar. The philosopher says, there is no
heat in the fire, meaning that the fire has
not the sensation of heat. His meaning is
just; and the vulgar will agree with him,
as soon as they understand his meaning :
But his language is improper ; for there is
really a quality in the fire, of which the
proper name is heat ; and the name of heat
is given to this quality, both by philosophers
and by the vulgar, much more frequently than
to the sensation of heat. [242] This speech
of the philosopher, therefore, is meant by
him in one sense ; it is taken by the vulgar
in another sense. In the sense in which
they take it, it is indeed absurd, and so
t'.iey hold it to be. In the sense in which
he means it, it is true ; and the vulgar, as
soon as they are made to understand that
sense, will acknowledge it to be true. They
know, as well as the philosopher, that the
fire does not feel heat : and this is all that
he means by saying there is no heat in the

In the opinions of philosophers about
primary and secondary qualities, there have
been, as was before observed, several revo-
lutions, -f* They were distinguished, long be-
fore the days of A ristotle, by the sect called
Atomists : among whom Democritus made
a capital figure. Iu those times, the name
of quality was applied only to those we call
secondary qualities ; the primary, being con-
sidered as essential to matter, were n t
called qualities. X That the atoms, which
they held to be the first principles of things,
were extended, solid, figured, and movable,
there was no doubt ; but the question was,
whether they had smell, taste, and colour ?
or, as it was commonly expressed, whether
they had qualities ? The Atomists main-
tained, that they had not ; that the quali-
ties were not in bodies, but were something
resulting from the operation of bodies upon
our senses. §

* All this ambiguity was understood and articu.
lately explai edby Conner philos >phers. See abovr,
notes at pp 20.5 and 31", and No'e D.— H.

tSee N.ite D H.

X The Atomists derived the qualitative attributes
of things troin the quantitative — H.

i, Still Democritus suppose I certain real or ob-
jective causes tor tliesubj-ct . e di'lorences of our

It would seem that, when men began to
speculate upon this subject, the primary
qualities appeared so clear and manifest
that they could entertain no doubt of their
existence wherever matter existed ; but the
secondary so obscure that they were at a
loss where to place them. They used this
comparison : as fire, which is neither in the
flint nor in the steel, is produced by their
collision, so those qualities, though not in
bodies, are produced by their impulse upon
our senses. [243]

This doctrine was opposed by- Aristotle.*
He believed taste and colour to be substan-
tial forms of bodies, and that their species,
as well as those of figure and motion, are
received by the senses. ■)■

In believing that what we commonly
call taste and colour, is something really
inherent in body, and does not depend upon
its being tasted and seen, he followed nature.
But, in believing that our sensations of
taste and colour are the forms or species of
those qualities received by the senses, he
followed his own theory, which was an ab-
surd fiction. -f- Des Cartes not only shewed
the absurdity of sensible species received by
the senses, but gave a more just and more
intelligible account of secondary qualities
than had been given before. Mr Locke
followed him, and bestowed much pains
upon this subject. He was the first, I
think, that gave them the name of secondary
qualities,} which has been very generally
adopted. He distinguished the sensation
from the quality in the body, which is the
cause or occasion of that sensation, and
shewed that there neither is nor can be any
similitude between them.§

By this account, the senses are acquitted
of putting any fallacy upon us ; the sensation
is real, and no fallacy ; the quality in the
body, which is the cause or occasion of this
sensation, is likewise real, though the nature
of it is not manifest to our senses. If we
impose upon ourselves, by confounding the
fensation with the quality that occasions
it, this is owing to rash judgment or weak
understanding, but not to any false testi-
mony of our senses.

This account of secondary qualities I take

sensations Thus, in the different forms, positions,
and relations of atoms, he sought the ground of
difference of tastes, colours, heat and cold, &c. See
Theophrastus Be Sensu, f, (i5 —Aristotle Be Anima,
iii 2. — Galen Be Elementis— Simplicius in Phys.
Auscult libros, t I itl, b.— H

* Aristotle admitted that the doctrine in question
was true, of colour, taste, &c , as 2Br ' iyigyuuv, hut
not true of them as *«,-« iuntiur. See be Anima
iu.2 H. ^

t This is rot really Aristo'le's doctrine.— H.

t Locke only gave a new meaning to old terms.
1 he first and second or the primary and secondary
qualities of Aristotle, denoted a distinction similar
to, but not identical with, that in question— H.

$ He distinguished nothing which had not been
more precisely di. criminated by Aristotle and the
t artesians. — H.

[21-2, 24.1]





to be very just ; and if Mr Locke had
stopped here, he would have left the matter
very clear. But he thought it necessary to
introduce the theory of ideas, to explain the
distinction between primary and secondary
qualities, and by that means, as I think,
perplexed and darkened it.

When philosophers speak about ideas, we
are often at a loss to know what they mean
by them, and may be apt to suspect that
they are mere fictions, that have no exist-
ence. [244] They have told us, that, by the
ideas which we have immediately from our
senses, they mean our sensations.* These,
indeed, are real things, and not fictions.
We may, by accurate attention to them,
know perfectly their nature ; and, if philo-
sophers would keep by this meaning of the
word idea, when applied to the objects of
sense, they would at least be more intelli-
gible. Let us hear how Mr Locke explains
the nature of those ideas, when applied to
primary and secondary qualities, Book 2,
chap 8, § 7) tenth edition. " To discover
the nature of our ideas the better, and to
discourse of them intelligibly, it will be con-
venient to distinguish them, as they are
ideas, or perceptions in our minds, and as
they are modifications of matter in the bodies
that cause such perceptions in us, that so
we may not think (as perhaps usually is
done) that they are exactly the images and
resemblances of something inherent in the
subject ; most of those of sensation beinji',
in the mind, no more the likeness of some-
thing existing without us, than the names
that stand for them are the likeness of our
ideas, which yet, upon hearing, they are apt
to excite in us."

This way of distinguishing a thing, first,
as what it is ; and, secondly, as what it is
not, is, I apprehend, a, very extraordinary
way of discovering its nature.-f And if ideas
are ideas or perceptions in our minds, and,
at the same time, the modifications of mat-
ter in the bodies that cause such percep-
tions in us, it will be no easy matter to
discourse of them intelligibly.

The discovery of the nature of ideas is
carried on in the next section, in a manner
no less extraordinary. tC Whatsoever the
mind perceives in itself, or is the immediate
object of perception, thought, or under-
standing, that I call idea ; and the power
to produce any idea in our mind, I call
quality of the subject wherein that power
is. Thus, a snowball having the power to
produce in us the ideas of white, cold, and
round — the powers to produce those ideas

• The Cartesians, particularly Malebranche, dis.
tinguished the Idea and the Feeling (sentiment, sensa-
tio.J Of the primary qualities in their doctrine we
have Ideas; of the secondary, only Feelings.— H.

t This and t-oine of the following strictures on
Locke are rather hypercritical. — H.

[241-246 1

in us, as they are in the snowball, I call
qualities ; and, as they are sensations, or
perceptions in our understandings, I call
them ideas ; which ideas, if I speak of
them sometimes as in the things themselves,
I would be understood to mean those quali-
ties hi the objects which produce them in
us." [245]

These are the distinctions which Mr
Locke thought convenient, in order to dis-
cover the nature of our ideas of the quali-
ties of matter the better, and to discourse
of them intelligibly. I believe it will be
difficult to find two other paragraphs in the
essay so unintelligible. Whether this is to be
imputed to the intractable nature of ideas,
or to an oscitancy of the author, with which
he is very rarely chargeable, I leave the
reader to judge. There are, indeed, seve-
ral other passages in the same chapter, in
which a like obscurity appears ; but I do
not chuse to dwell upon them. The con-
clusion drawn by him from the whole is,
that primary and secondary qualities are
distinguished by this, that the ideas of the
former are resemblances or copies of them,
but the ideas of the other are not resem-
blances of them. Upon this doctrine, I beg
leave to make two observations.

First, Taking it for granted that, by the
ideas of primary and secondary qualities,
he means the sensations* they excite in us,
I observe that it appears strange, that a
sensation should be the idea of a quality in
body, to which it is acknowledged to bear
no resemblance. If the sensation of sound
be the idea of that vibration of the sound-
ing body which occasions it, a surfeit may,
for the same reason, be the idea of a feast.

A second observation is, that, when Mr
Locke affirms, that the ideas of primary
qualities — that is, the sensations* they raise
in us — are resemblances of those qualities,
he seems neither to have given due atten-
tion to those sensations, nor to the nature
of sensation in general. [246]

Let a man press his hand against a hard
body, and let him attend to the sensation
he feels, excluding from his thought every
thing external, even the body that is the
cause of his feeling. This abstraction, in-
deed, is difficult, and seems to have been
i little, if at all practised. But it is not im-
possible, and it is evidently the only way to
understand the nature of the sensation. A
due attention to this sensation will satisfy

» Here, as formerly, {vide supra, notes at pp 208,
290, &c.,) Reid will insist on giving a more limited
meaning to the term Sensation than Locke did, and
on criticising him by that imposed meaning. The
Sensation of Locke was equivalent to the Sensation
and Perception of Reid. It is to be observed that
Locke did not, like the Cartesians, distinguish the
Idea (corresponding to Reid's Perception) from the
Feeling (sentiment, sens tio) corresponding to Reid'l
Sensation.— 11



[[essay II

him tnat it is no more like hardness in a
body than the sensation of sound is like
vibration in the sounding body.

I know of no ideas but my conceptions ;
and my idea of hardness in a body, is the
conception of such a cohesion of its parts
as requires great force to displace them. I
have both the conception and belief of this
quality in the body, at the same time that
I have the sensation of pain, by pressing
my hand against it. The sensation and
perception are closely conjoined by my
constitution ; but I am sure they have no
similitude ; I know no reason why the one
should be called the idea of the other, which
does not lead us to call every natural effect
the idea of its cause.

Neither did Mr Locke give due attention
to the nature of sensation in general, when
he affirmed that the ideas of primary qua-
lities — that is, the sensations* excited
by them— are resemblances of those quali-

That there can be nothing like sensation
in an insentient being, or like thought in
an unthinking being, is self-evident, and
has been shewn, to the conviction of all
men that think, by Bishop Berkeley ; yet
this was unknown to Mr Locke. It is an
humbling consideration, that, in subjects of
this kind, self-evident truths may be hid
from the eyes of the most ingenious men.
But we have, withal, this consolation, that,
when once discovered, they shine by their
own light : and that light can no more be
put out. [247]

Upon the whole, Mr Locke, in making
secondary qualities to be powers in bodies
to excite certain sensations in us, has given
a just and distinct analysis of what our
senses discover concerning them ; but, in
applying the theory of ideas to them and
to the primary qualities, he has been led to
say things that darken the subject, and that
will not bear examination. -J*

Bishop Berkeley having adopted the sen-
timents common to philosophers, concern-
ing the ideas we have by our senses — to wit,
that they are all sensations — saw more clearly
the necessary consequence of this doctrine;
which is, that there is no material world —
no qualities primary or secondary — and,
consequently, no foundation for any dis-
tinction between them.$ He exposed the
absurdity of a resemblance between our

» No ; not Sensations in Reiti's meaning ; but Per-
cepts — the immediate objects we ate conscious of in
the cognitions of sense.— H.

1 The Cartesians did not apply the term ideas to
our sensations of the secondary qualities. — H.

J See above, p. 142, note *. The mere distinction
of primary and secondary qualities, of perception and
sensation, is of no importance against Idealism, if the
primary qualities as immediately perceived, (i e. as
k'own tn consciousness,) be only conceptions, no-
tions, or modit-cations of mil d itselt. See following

sensations and any quality, primary or
secondary, of a substance that is supposed
to be insentient. Indeed, if it is granted
that the senses have no other office but to
furnish us with sensations, it will be found
impossible to make any distinction between
primary and secondary qualities, or even to
maintain the existence of a material world.
From the account I have given of the
various revolutions in the opinions of philo-
sophers about primary and secondary qua-
lities, I think it appears that all the dark-
ness and intricacy that thinking men have
found in this subject, and the errors they
have fallen into, have been owing to the
difficulty of distinguishing clearly sensa-
tion from perception — what we feel from
what we perceive.

The external senses have a double pro-
vince — to make us feel, and to make us
perceive. They furnish us with a variety
of sensations, some pleasant, others painful,
and others indifferent ; at the same time,
they give us a conception and an invincible
belief of the existence of external objects.
This conception of external objects is the
work of nature. The belief of their exist-
ence, which our senses give, is the work of
nature; so likewise is the sensation that
accompanies it. This conception and be-
lief which nature produces by means of the
senses, we call perception.* [248] The
feeling which goes along with the percep-
tion, we call sensation. The perception and
its corresponding sensation are produced at
the same time. In our experience we never
find them disjoined. Hence, we are led to
consider them as one thing, to give them
one name, and to confound their different
attributes. It becomes very difficult to
separate them in thought, to attend to each
by itself, and to attribute nothing to it
which belongs to the other.

To do this, requires a degree of attention
to what passes in our own minds, and a
talent of distinguishing things that differ,
which is not to be expected in the vulgar,
and is even rarely found in philosophers ;
so that the progress made in a just analysis
of the operations of our senses has been
very slow. The hypothesis of ideas, so
generally adopted, hath, as I apprehend,
greatly retarded this progress, and we might
hope for a quicker advance, if philosophers
could so far humble themselves as to be-
lieve that, in every branch of the philosophy
of nature, the productions of human fancy
and conjecture will be found to be dross ;
and that the only pure metal that will en-
dure the test, is what is discovered by
patient observation and chaste induction.

* If the conception, like the odief, be subjectfre
in perception, we have no refuge from Idealism in
this doctrine. Sre above, the notes at pp. 128.130,
183, &c, and Nolo C H.

[217, 21S]





Besides primary and secondary qualities
of bodies, there are many other immediate
objects of perception. Without pretending
to a complete enumeration, I think they
mostly fall under one or other of the follow-
ing, classes. Is', Certain states or condi-
tions of our own bodies. 2d, Mechanical
powers or forces. 3rf, Chemical powers.
4/A, Medical powers or virtues. 5th, Vege-
table and animal powers. [249]

That we perceive certain disorders in our
own bodies by means of uneasy sensations,
which nature hath conjoined with them, will
not be disputed. Of this kind are toothache,
headache, gout, and every distemper and
hurt which we feel. The notions which
our sense gives of these, have a strong
analogy to our notions of secondary qualities.
Both are similarly compounded, and may
be similarly resolved, and they give light to
each other.

In the toothache, for instance, there is,
first,, a painful feeling ; and, secondly, a
conception and belief of some disorder in
the tooth, which is believed to be the cause
of the uneasy feeling. " The first of these
is a sensation, the second is perception ;
for it includes a conception and belief of an
external object. But these two things,
though of different natures, are so con-
stantly conjoined in our experience and in
our imagination, that we consider them as
one. We give the same name to both ; for
the toothache is the proper name of the
pain we feel ; and it is the proper name of
the disorder in the tooth which causes that
pain. _ If it should be made a question
whether the toothache be in the mind that
feels it, or in the tooth that is affected,
much might be said on both sides, while it
is not observed that the word has two mean-
ings, -f But a little reflection satisfies us,
that the pain is in the mind, and the dis-
order in the tooth. If some philosopher
should pretend to have made the discovery
that the toothache, the gout, the headache,
are only sensations in the mind, and that
it is a vulgar error to conceive that they
are distempers of the body, he might defend
his system in the same maimer as those
who affirm that there is no sound, nor
colour, nor taste in bodies, defend that para-
dox. But both these systems, like most

* There is no such perception, properly so called,
The cognition is merely an inference from the
feeling ; and its object, at least, only some hypothe-
tical representation of a really ianotum quid. Here
the subjective element preponderates so greatly as
almost to extinguish the objective — I !.

t This is not correct. See above, p. 205, col. b
note *, and tJote D.— H.

paradoxes, will be found to be only an abus '.
of words.

We say that we feel the toothache, not
that we perceive it. On the other hand, we
say that we perceive the colour of a body,
not that we feel it. Can any reason be given
for this difference of phraseology ? [250]
In answer to this question, I apprehend
that, both when we feel the toothache and
when we see a coloured body, there is sensa-
tion and perception conjoined. But, in the
toothache, the sensation being very painful,
engrosses the attention ; and therefore we
speak of it as if it were felt only, and not
perceived : whereas, in seeing a coloured
body, the sensation is indifferent, and draws
no attention. The quality in the body,
which we call its colour, is the only object
of attention ; and therefore we speak of it
as if it were perceived and not felt. Though
all philosophers agree that, in seeing colour
there is sensation, it is not easy to persuade
the vulgar that, in seeing a coloured body,
when the light is not too strong nor the
eye inflamed, they have any sensation or
feeling at all.

There are some sensations, which, though
they are very often felt, are never attended
to, nor reflected upon. We have no con-
ception of them ; and, therefore, in language
there is neither any name for them, nor
any form of speech that supposes their
existence. Such are the sensations of colour,
and of all primary qualities ; and, therefore,
those qualities are said to be perceived, but
not to be felt. Taste and smell, and heat
and cold, have sensations that are often
agreeable or disagreeable, in such a degree
as to draw our attention ; and they are
sometimes said to be felt, and sometimes to
be perceived. When disorders of the body
occasion very acute pain, the uneasy sensa-
ation engrosses the attention, and they are
said to be felt, not to be perceived.*

There is another question relating to
phraseology, which this subject suggests.
A man says, he feels pain in such a parti-
cular part of his body ; in his toe for in-
stance. Now, reason assures us that pain
being a sensation, can only be in the sen-
tient being, as its subject — that is, in the
mind. And, though philosophers have dis-
puted much about the place of the mind ;

Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 72 of 114)