Thomas Reid.

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

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none. What has been said of the irresis-
tible and immediate belief of the existence
of objects distinctly perceived, I mean only
to affirm with regard to persons so far ad-
vanced in understanding as to distinguish
objects of mere imagination from things
which have a real existence. Every man
knows that he may have a notion of Don
Quixote, or of Garagantua, without any
belief that such persons ever existed ; and
that of Julius Caesar and Oliver Crom-
well, he has not only a notion, but a belief
that they did really exist. [Ill] But
whether children, from the time that they
begin to use their senses, make a distinction
between things which are only conceived or
imagined, and things which really exist,
may be doubted. Until we are able to
make this distinction, we cannot properly
be said to believe or to disbelieve the
existence of anything. The belief of the
existence of anything seems to suppose a
notion of existence — a notion too abstract,
perhaps, to enter into the mind of an in-
fant. I speak of the power of perception
in those that are adult and of a sound
mind, who believe that there are some
things which do really exist ; and that there
are many things conceived by themselves,
and by others, which have no existence.
That such persons do invariably ascribe
existence to everything which they distinctly
perceive, without seeking reasons or argu-
ments for doing so, is perfectly evident from
the whole tenor of human life.

The account I have given of our percep-
tion of external objects, is intended as a
faithful delineation of what every man, come
to years of understanding, and capable of
giving attention to what passes in his own
mind, may feel in himself. In what man-

ner the notion of external objects, and the
immediate belief of their existence, is pro-
duced by means of our senses, I am not
able to shew, and I do not pretend to shew.
If the power of perceiving external objects
in certain circumstances, be a part of the
original constitution of the human mind,
all attempts to account for it will be vain.
No other account can be given of the con-
stitution of things, but the will of Him that
made them. As we can give no reason why
matter is extended and inert, why the mind
thinks and is conscious of its thoughts, but
the will of Him who made both ; so I sus-
pect we can give no other reason why, in
certain circumstances, we perceive external
objects, and in others do not.*

The Supreme Being intended that we
should have such knowledge of the material
objects that surround us, as is necessary in
order to our supplying the wants of nature,
and avoiding the dangers to which we are
constantly exposed ; and he has admirably

purpose. [112] If the intelligence we have
of external objects were to be got by
reasoning only, the greatest part of men
would be destitute of it ; for the greatest
part of men hardly ever learn to reason ;
and in infancy and childhood no man can
reason : Therefore, as this intelligence of
the objects that surround us, and from
which we may receive so much benefit or
harm, is equally necessary to children and
to men, to the ignorant and to the learned,
God in his wisdom conveys it to us in a
way that puts all upon a level. The inform-
ation of the senses is as perfect, and gives
as full conviction to the most ignorant as to
the most learned.



An object placed at a proper distance,
and in a good light, while the eyes are shut,
is not perceived at all ; but no sooner do
we open our eyes upon it than we have, as
it were by inspiration, a certain knowledge
of its existence, of its colour, figure, and
distance. This is a fact which every one
knows. The vulgar are satisfied with know-
ing the fact, and give themselves no trouble
about the cause of it : but a philosopher is
impatient to know how this event is pro-
duced, to account for it, or assign its cause.

This avidity to know the causes of things
is the parent of all philosophy, true and
false. Men of speculation place a great
part of their happiness in such knowledge.

• See above.p. 128, b, note *,»niip. 130, b, note*:
also Note A.— H.

Till, 112]


Account op a phenomenon.


Felix qui potuit rerum cognoscere causas,
has always been a sentiment of human
nature. But, as in the pursuit of other
kinds of happiness men often mistake the
road, so in none have they more frequently
done it than in the philosophical pursuit of
the causes of things. [113]

It is a dictate of common sense, that the
causes we assign of appearances ought to
be real, and not fictions of human imagina-
tion. It is likewise self-evident, that such
causes ought to be adequate to the effects
that are conceived to be produced by them.
That those who are less accustomed to
inquiries into the causes of natural appear-
ances, may the better understand what it
is to shew the cause of such appearances,
or to account for them, I shall borrow a
plain instance of a phenomenon or appear-
ance, of which a full and satisfactory ac-
count has been given. The phaenomenon
is this : That a stone, or any heavy body,
falling from a height, continually increases
its velocity as it descends ; so that, if it
acquire a certain velocity in one second of
time, it will have twice that velocity at the
end of two seconds, thrice at the end of
three seconds, and so on in proportion to
the time. This accelerated velocity in a
stone falling must have been observed from
the beginning of the world ; but the first
person, as far as we know, who accounted
for it in a proper and philosophical manner,
was the famous Galileo, after innumer-
able false and fictitious accounts had been
given of it.

He observed, that bodies once put in
motion continue that motion with the same
velocity, and in the same direction, until
they be stopped or retarded, or have the
direction of their motion altered, by some
force impressed upon them. This property
of bodies is called their inertia, or inac-
tivity; for it implies no more than that
bodies cannot of themselves change their
state from rest to motion, or from motion
to rest. He observed also, that gravity acts
constantly and equally upon a body, and
therefore will give equal degrees of velocity
to a body in equal times. From these
principles, which are known from experi-
ence to be fixed laws of nature, Galileo
shewed that heavy bodies must descend
with a velocity uniformly accelerated, as
by experience they are found to do. [114]
For if the body by its gravitation ac-
quire a certain velocity at the end of one
second, it would, though its gravitation
should cease that moment, continue to go on
with that velocity ; but its gravitation con-
tinues, and will in another second give it an
additional velocity, equal to that which it gave
in the first ; so that the whole velocity at
the end of two seconds, will be twice as great
as at the end of one. In like manner, this


velocity being continued through the third
second, and having the same addition by
gravitation as in any of the preceding, the
whole velocity at the end of the third second
will be thrice as great as at the end of the
first, and so on continually.

We may here observe, that the causes
assigned of this phsenomenou are two : First,
That bodies once put in motion retain their
velocity and their direction, until it is changed
by some force impressed upon them. Se-
condly, That the weight or gravitation of a
body is always the same. These are laws
of Nature, confirmed by universal experi-
ence, and therefore are not feigned but true
causes. Then, they are precisely adequate
to the effect ascribed to them ; they must
necessarily produce that very motion in
descending bodies which we find to take
place ; and neither more nor less. The
account, therefore, given of this phsenom-
non, is just and philosophical ; no other
will ever be required or admitted by those
who understand this.

It ought likewise to be observed, that
the causes assigned of this phenomenon,
are things of which we can assign no cause.
Why bodies once put in motion continue to
move — why bodies constantly gravitate to-
wards the earth with the same force — no
man has been able to shew : these are facts
confirmed by universal experience, and
they must no doubt have a cause ; but their
cause is unknown, and we call them laws
of Nature, because we know no cause of
them, but the will of the Supreme Being.

But may we not attempt to find the cause
of gravitation, and of other phsenomena,
which we call laws of Nature ? No doubt
wemay. [115] Weknownotthe limit which
has been set to human knowledge, and our
knowledge of the works of God can never
be carried too far. But, supposing gravita-
tion to be accounted for, by an sethereal
elastic medium, for instance, this can only be
done, first, by proving the existence and the
elasticity of this medium ; and, secondly,
by shewing that this medium must neces-
sarily produce that gravitation which bodies
are known to have. Until this be done,
gravitation is not accounted for, nor is
its cause known; and when this is done,
the elasticity of this medium will be consi-
dered as a law of nature whose cause is
unknown. The chain of natural causes has,
not unfitly, been compared to a chain hang-
ing down from heaven : a link that is dis-
covered supports the links below ifc, but it
must itself be supported ; and that which
supports it must be supported, until we
come to the first link, which is supported
by the throne of the Almighty. Every na-
tural cause must have a cause, until we
ascend to the first cause, which is uncaused,
and operates not by necessity but by will



[essay II.

By what has been said in this chapter,
those who are but little acquainted with
philosophical inquiries, may see what is
meant by accounting for a phsenomenon,
or shewing its cause, which ought to be well
understood, in order to judge of the theories
by which philosophers have attempted to
account for our perception of external ob-
jects by the senses.


SENTIMENTS* op philosophers about the


How the correspondence is carried on

between the thinking principle within us, and
the material world without us, has always
been found a very difficult problem to those
philosophers who think themselves obliged
to account for every phsenomenon in nature.
[116] Many philosophers, ancient and
modern, have employed their invention to
discover how we are made to perceive ex-
ternal objects by our senses ; and there
appears to be a very great uniformity in
their sentiments in the main, notwithstand-
ing their variations in particular points.

Plato illustrates our manner of perceiving
the objects of sense, in this manner. He
supposes a dark subterraneous cave, in
which men lie bound in such a manner
that they can direct their eyes only to one
part of the cave : far behind, there is a
light, some rays of which come over a wall
to that part of the cave which is before the
eyes of our prisoners. A number of per-
sons, variously employed, pass between
them and the light, whose shadows are seen
by the prisoners, but not the persons them-

In this manner, that philosopher con-
ceived that, by our senses, we perceive the
shadows of things only, and not things
themselves. He seems to have borrowed
his notions on this subject, from the Pytha-
goreans, and they very probably from Py-
thagoras himself. If we make allowance
for Plato's allegorical genius, his sentiments
on this subject, correspond very well with

• Sentiment, as here and elsewhere employed by
Reid, in the meaning of opinion, (sententia,) is not
to be imitated. There are, undoubtedly, precedents
to be found for such usage in English writers ; and, In
the French and Italian languages, this is one of the
ordinary signflcations of the word.— H

f It is not easy to conceive hy what principle the
order of the history of opinions touching Perception,
contained in the nine following chapters, is deter-
mined. It is not chronological, and it is not systematic.
Of these theories, there is a very able survey, by M.
Royer t'ollard, among the fragments of his lectures,
in the third volume of Jouffroy's " Oeuvres de Reid."
That distinguished philosopher has, however, placed
too great a reliance upon tt a accuracy of Reid — H.

those of his scholar, Aristotle, and of the
Peripatetics. The shadows of Plato may
very well represent the species and phan-
tasms of the Peripatetic school, and the
ideas and impressions of modern philo-

* Thii interpretation of the meaning of Plato's
comparison of the cave exhibits a curious mistake,
in which Reid is followed by Mr Stewart and many
others, and which, it is remarkable, has never yet
been detected. In the similitude in question, (which
will be found in the seventh book of the Republic,)
Plato is supposed to intend an illustration of the
mode in which the shadows or vicarious images of
external things are admitted into the mind— to
typify, in short, an hypothesis of sensitive perception.
On this supposition, the identity of the Platonic,
Pythagorean, and Peripatetic theories of this pro-
cess is inferred. Nothing can, however, be more
groundless than the supposition ; nothing more erro-
neous than the inference. By his cave, images, and
shadows, Plato meant simply to illustrate the grand
principle of his philosophy — that the Sensible or Ec
typal world, (phenomenal, transitory, ytyvofttvov, h
*«* ,u.r, 6v,) stands to the Noetic or Archetypal, (sub-
stantial, permanent, him h,) in the same relation
of comparative unreality, in which the shadows of the
images of sensible existences themselves, stand to the
things of which they are the dim and distant adum-
brations. In the language of an illustrious poet —
" An nescis, quscunque heic sunt, qua; hac nocte

Cmnia res prorsus veras non esse, sed umbras,
Aut specula, unde ad nos aliena elucet imago ?
Terra quidem, et maria alta, atque his circumfluus

Etquse consistunt ex iis, haec omnia tenueis
Sunt umbrae, humanos qua? tanquam sotnnia qute-

Fertingunt animos, fallaci et imagine ludunt,
Nunquam eadem, fluxu semper variata perenni,
Sol autera, Luneque globus, fulgentiaque astra
Ctetera, sint quamvis meliori praxlita vita,
Et donata ffivo immortal i, haec ipsa tamen sunt
.Xterni specula, in qua? animus, qui est inde profec

Inspiciens, patris quodam quasi tactus amore,
Ardescit. Verum quoniam heic non perstat et ultra
Nescio quid scquitur secum, tacitusque requirit,
Nosse licet circum haec ipsum consistere verum,
Non fin em : sed enim esse aliud quid, cujus imago
Splendet in iis, quod per se ipsum est, et principium

Omnibus sternum, ante omnem numerumque diem.

In quo alium Solem atque aliam splendescere Lu-

Adspicias, aliosque orbes, alia astra manere,
Terramque, fluviosque alios, atque aera, et ignem,
Et nemora, atque aliis erfare ammalia silvis."

And as the comparison is misunderstood, so no-
thing can be conceived more adverse to the doctrine
of Plato than the theory it is supposed to elucidate.
Plotinus, indeed, formally refutes, as contrary to the
Platonic, the very hypothesis thus attributed to his
master. (Enn. IV., 1. vi., cc. 1., 3.) The doctrineof
the Flatonists on this point has been almost wholly
neglected; and the author among them whose work
contains its most articulate developement has been
so completely overlooked, both by scholars and phi-
losophers, that his work is of the rarest, while even
his name is mentioned in no history of philosophy.
It is here sufficient to state, that the t'&tvXa., thu
koyoi yvwrtKol, the forms representative of external
things, and corresponding to the species sensiles ex-
press* of the schoolmen, were not held by the Plato,
nists to be derived from without. Prior to the at t ol
perception, they have a latent but real existence in
the soul ; and, by the impassive energy of the mind
itself, are elicited into consciousness, on occasion of the
impression (xiyv l {ri$,x&8oe i Eu$*iris)rn&fieontheex.teT.
nal organ, and of the vital form {turtxov ilios), in con-
sequence thereof, sublimated in the animal life. The
verses of Boethius, which have been so frequently
misunderstood, contain an accurate statement of the
Platonic theory of perception. After refuting the

1 116")

Chap, vii.]



Two thousand years after Plato, Mr
Locke, who studied the operations of the
human mind so much, and with so great
success, representsourmanner of perceiving
external objects,, by a similitude very much
resembling that of the cave. , " Methinks,"
says he, "the understanding is not much
unlike a closet wholly shut from light, with
only some little opening left, to let in exter-
nal visible resemblances or ideas of things
without. Would the pictures coming into
such a dark room but stay there, and lie so
orderly as to be found upon occasion, it
would very much resemble the under-
standing of a man, in reference to all objects
of sight, and the ideas of them. " [117]

Plato's subterranean cave, and Mr Locke's
dark closet, may be applied with ease to all
the systems of perception that have been
invented : for they all suppose that we
perceive not external objects immediately,
and that the immediate objects of percep-
tion are only certain shadows of the ex-
ternal objects. Those shadows or images,
which we immediately perceive, were by
the ancients called species, forms, phan-
tasms. Since the time of Des Cartes, they
have commonly been called ideas, and by
Mr Hume, impressions. But all philoso-
phers, from Plato to Mr Hume, agree in
this, That we do not perceive external ob-
jects immediately, and that the immediate
object of perception must be some image
present to the mind.* So far there ap-

Stoical doctrine of the passivity of mind in this pro-
cess, he proceeds : —

" Mens est efficiena magis

Longe causa potentior,

Quam quee materia; modo

lmpressas patitur notas.

Prcecedit tamen excitant

Ac vires animi movens

Vivo in corpore passio.

Cum vel lux oculos ferit,

Vel vox auribus instrepit:

Turn mentis'yigor excitus

Quas inius species tenet,

Ad motus similes vocans,

Notis applicat exteris,

Introrsumque recondiiis

Formis miscet imagines."
I cannot now do more than indicate the contrast
of this doctrine to the Peripatetic (I do not say Aris-
totelian) theory, and its approximation to the Carte-
sian and Leibnitzian hypotheses ; which, however,
both attempt to explain, what the Platonic did not—
how the mind, ex hypothesi, above all physical in-
fluence, is determined, on the presence of the un-
known reality within the sphere of sense, to call into
consciousness the representation through which that
reality is made known to us. I may add, that not
merely the Platonists, but some of the older Peripa-
tetics held that the soul virtually contained within it-
self representative forms, which were only excited
by the external reality ; as Theophrastus and The-
mistius, to say nothing of the Platonizing Porphyry,
Simplicius and Ammonius Hermia? ; and the same
opinion, adopted probably from the latter, by his
pupil, the Arabian Adelandus, subsequently be-
came even the common doctrine of the Moorish

I shall afterwards have occasion to notice that
Bacon has also wrested Plato's similitude of the cave
from its genuine signification — H.
* This is not correct. There were philosophers

pears an unanimity, rarely to be found among
philosophers on such abstruse points.*

If it should be asked, Whether, accord-
ing to the opinion of philosophers, we per-
ceive the images or ideas only, and infer the
existence and qualities of the external ob-
ject from what we perceive in the image ;
or, whether we really perceive the external
object as well as its image ? — the answer
to this question is not quite obvious, -f-

On the one hand, philosophers, if we ex-
cept Berkeley and Hume, believe the ex-
istence of external objects of sense, and call
them objects of perception, though not im-
mediate objects. But what they mean by
a mediate object of perception I do not find
clearly explained : whether they suit their
language to popular opinion, and mean that
we perceive external objects in that figura-
tive sense in which we say that we perceive
an absent friend when we look on his pic-
ture ; or whether they mean that, really,
and without a figure, we perceive both the
external object and its idea in the mind.
If the last be their meaning, it would follow
that, in every instance of perception, there
is a, double object perceived: [118] that
I perceive, for instance, one sun in the
heavens, and another in my own mind.J
But I do not find that they affirm this ;
and, as it contradicts the experience of all
mankind, I will not impute it to them.

It seems, therefore, that their opinion is,
That we do not really perceive the external
object, but the internal only ; and that, when
they speak of perceiving external objects,
they mean it only in a popular or in a figur-
ative sense, as above explained. Several
reasons lead me to think this to be the
opinion of philosophers, beside what is
mentioned above. First, If we do really
perceive the external object itself, there
seems to be no necessity, no use, for an
image of it. Secondly, Since the time of
Des Cartes, philosophers have very gene-
rally thought that the existence of external
objects of sense requires proof, and can only
be proved from the existence of their ideas.
Thirdly, The way in which philosophers
speak of ideas, seems to imply that they
are the only objects of perception.

who held a purer and preciser doctrine of immediate
perception than Reid himself contemplated. — H.

* Reid himself, like the philosophers in general,
really holds, that we do not perceive external tilings
immediately, if he does not allow us a consciousness
of the non-ego. It matters nnt whether the external
reality be represented in a tertium quid, or in a mo-
dification of the mind itself; in either case, it is not
known in itself, but in something numerically dif-
ferent.— H.

t Nothing can be clearer than wouldbe this answer.

In perception, the external reality, (the mediate

object,} is only known to us in and through the im-
mediate object, i. e., the representation of which we
are conscious. As existing, and beyond the 6phere of
consciousness, the external reality is unknown — H.

1 " Et solem geminum et duplices se ostendere
Thebas!"— H.

[117, 118]



[essay n.

Having endeavoured to explain what is
common to philosophers in accounting for
our perception of external objects, we shall
give some detail of their differences.

The ideas by which we perceive external
objects, are said by some to be the ideas of
the Deity ; but it has been more generally
thought, that every man's ideas are proper
to himself, and are either in his mind, or
in his sensorium, where the mind is imme-
diately present. The first is the theory of
Malebranche ; the second we shall call the
common theory.

With regard to that of Malebranche, it
seems to have some affinity with the Pla-
tonic notion of ideas,* but is not the same.
Plato believed that there are three eternal
first principles, from which all things have
their origin — matter, ideas, and an efficient
cause. Matter is that of which all things
are made, which, by all the ancient philo-
sophers, was conceived to be eternal. [119]
Ideas are forms without matter of every
kind of things which can exist ; which forms
were also conceived by Plato to be eternal
and immutable, and to be the models or
patterns by which the efficient cause — that
is, the Deity — formed every part of this
universe. These ideas were conceived to
be the sole objects of science, and indeed
of all true knowledge. While we are im-
prisoned in the body, we are prone to give
attention to the objects of sense only ; but
these being individual things, and in a con-
stant fluctuation, being indeed shadows
rather than realities, cannot be the object
of real knowledge. All science is employed
not about individual things, but about
things universal and abstract from matter.
Truth is eternal and immutable, and there-
fore must have for its object eternal and
immutable ideas ; these we are capable of

Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 59 of 114)