Thomas Reid.

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

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— rt S<ie above ' p ' w85 ' note t. and p. 358, note *.

t See above, p. 4-t'?, b, not? H.

% See above p. 269, a, note 5 ; and p. 893, b, note
*. — H.




believed themselves to be nothing but a train
of ideas and impressions, or to have a more
permanent existence, I have not learned,
having never seen any of their writings ; nor
do I know whether any of this sect did write
in support of their principles. One would
think they who did not believe that there
was any person to read, could have little
inducement to write, unless they were
prompted by that inward monitor which
Persius makes to be the source of genius
and the teacher of arts. There can be no
doubt, however, of the existence of such a
sect, as they are mentioned by many
authors, and refuted by some, particularly
by Burner, in his treatise of first principles.

Those Egoists and Mr Hume seem to
me to have reasoned more consequentially
from Des Cartes' principle than he did him-
self; and, indeed, I cannot help thinking,
that all who have followed Des Cartes'
method, of requiring proof by argument of
everything except the existence of their
own thoughts, have escaped the abyss of
scepticism by the help of weak reasoning
and strong faith more than by any other
means. And they seem to me to act more
consistently, who, having rejected the first
principles on which belief must be grounded,
have no belief, than they, who, like the
others, rejecting first principles, must yet
have a system of belief, without any solid
foundation on which it may stand.

The philosophers I have hitherto men-
tioned, after the time of Des Cartes, have
all followed his method, in resting upon the
truth of their own thoughts as a first
principle, but requiring arguments for the
proof of every other truth of a contingent
nature; but none of them, excepting Mr
Locke, has expressly treated of first princi-
ples, or given any opinion of their utility or
inutility. We only collect their opinion
from their following Des Cartes in requir-
ing proof, or pretending to offer proof of
the existence of a material world, which
surely ought to be received as a first princi-
ple, if anything be, beyond what we are
conscious of. [642]

I proceed, therefore, to consider what
Mr Locke has said on the subject of first
principles or maxims.

I have not the least doubt of this author's
candour in what he somewhere says, that
his essay was mostly spun out of his own
thoughts. Yet, it is certain, that, in many
of the notions which we are wont to ascribe
to him, others were before him, particularly
Des Cartes, Gassendi, and Hobbes. Nor
is it at all to be thought strange, that inge-
nious men, when they are got into the
same track, should hit upon the same

But, in the definition which he gives of
knowledge in general, and in his notions
[642, G43~]

concerning axioms or first principles, 1
know none that went before him, though
he has been very generally followed in both.

His definition of knowledge, that it con-
sists solely in the perception of the agree-
ment or disagreement of our ideas, has been
already considered. But supposing it to be
just, still it would be true, that some agree-
ments and disagreements of ideas must be
immediately perceived ; and such agree-
ments or disagreements, when they are
expressed by affirmative or negative propo-
sitions, are first principles, because their
truth is immediately discerned as soon as
they are understood.

This, I think, is granted by Mr Locke,
book 4, chap. 2. " There is a part of our
knowledge," says he, " which we may call
intuitive. In this the mind is at no pains
of proving or examining, but perceives the
truth as the eye does light, only by being
directed toward it. And this kind of know-
ledge is the clearest and most certain that
human frailty is capable of This part of
knowledge is irresistible, and, like bright
sunshine, forces itself immediately to be
perceived, as soon as ever the mind turns
its view that way." [643]

He farther observes — " That this intui-
tive knowledge is necessary to connect all
the steps of a demonstration."*

From this, I think, it necessarily follows,
that, in every branch of knowledge, we
must make use of truths that are intuitively
known, in order to deduce from them such
as require proof.

But I cannot reconcile this with what ho
says, § 8, of the same chapter : — " The
necessity of this intuitive knowledge in every
step of scientifical or demonstrative reason-
ing gave occasion, I imagine, to that mis-
taken axiom, that all reasoning was-ea? prce-
cognitis et praconcessis, which, how far it is
mistaken, I shall have occasion to shew
more at large, when I come to consider
propositions, and particularly those proposi-
tions which are called maxims, and to shew
that it is by a mistake that they are sup-
posed to be the foundation of all our know-
ledge and reasonings."

JL have carefully considered the chapter
on maxims, which Mr Locke here refers to ;
and, though one would expect, from the
quotation last made, that it should run con-
trary to what I have before delivered con-
cerning first principles, I find only two or
three sentonces in it, and those chiefly inci-
dental, to which I do not assent ; and I am
always happy in agreeing with a philoso-
pher whom I so highly respect.

He endeavours to shew that axioms or
intuitive truths are not innate. -f-

* See Stewart's " Elements," ii. p. 49. — H.
t He does more. He attempts to shew that they
are all generalizations from experience ; whereas ex-

2 a



[essay VI.

To this I agree. I maintain only, that
when the understanding is ripe, and when
we distinctly apprehend such truths, we
immediately assent to them. [644]

He observes, that self-evidence is not
peculiar to those propositions which pass
under the name of axioms, and have the
dignity of axioms ascribed to them. '

I grant that there are innumerable self-
evident propositions, which have neither
dignity nor utility, and, therefore, deserve
not the name of axioms, as that name is
commonly understood to imply not only
self-evidence, but some degree of dignity or
utility. That a man is a man, and that a.
man is not a horse, are self-evident propo-
sitions ; but they are, as Mr Locke very
justly calls them, trifling propositions. Til-
lotson very wittily says of such propositions,
that they are so surfeited with truth, that
they are good for nothing ; and as they de-
serve not the name of axioms, so neither
do they deserve the name of knowledge.

He observes, that such trifling self-evi-
dent propositions as we have named are not
derived from axioms, and therefore that all
our knowledge is not derived from axioms.

I grant that they are not derived from
axioms, because they are themselves self-
evident. But it is an abuse of words to call
them knowledge, as it is, to call them
axioms ; for no man can be said to be the
wiser or more knowing for having millions of
them in store.

He observes, that the particular propo-
sitions contained under a general axiom are
no less self-evident than the general axiom,
and that they are sooner known and under-
stood. Thus, it is as evident that my hand
is less than my body, as that a part is less
than the whole ; and I know the truth of
the particular proposition sooner than that
of the general.

This is true. A man cannot perceive the
truth of a general axiom, such as, that a
part is less than the whole, until he has the
general notions of a part and a whole formed
in his mind ; and, before he has these
general notions, he may perceive that his
hand is less than his body. [645]

A great part of this chapter on maxims
is levelled against a notion, which, it seems,
some have entertained, that all our know-
ledge is derived from these two maxims —
to wit, whatever is, is ; and it is impossible
for the same thing to be, and not to be. •

This I take to be a ridiculous notion,
justly deserving the treatment which Mr

perience only affords the occasions on which the
native (not innate) or a priori cognitions, virtually
possessed by the mind, actually manifest their exist-
ence H.

* These are called, the principle of Identity, and the
principle of Contradiction, or, more properly, Non-
contradiction. — H.

Locke has given it, if it at all merited his
notice. These are identical propositions j
they are trifling, and surfeited with truth.
No knowledge can be derived from them.

Having mentioned how far I agree with
Mr Locke concerning maxims or first prin.
ciples, I shall next take notice of two or
three things, wherein I cannot agree with

In the seventh section of this chapter, he
says, That, concerning the real existence of
all other beings, besides ourselves and a
first cause, there are no maxims.

I have endeavoured to shew that there
are maxims, or first principles, with regard
to other existences. Mr Locke acknowledges
that we have a knowledge of such existences,
which, he says, is neither intuitive nor de-
monstrative, and which, therefore, he calls
sensitive knowledge. It is demonstrable,
and was long ago demonstrated by Aristotle,
that every proposition to which we give a
rational assent, must either have its evi-
dence in itself, or derive it from some ante-
cedent proposition. And the same thing
may be said of the antecedent proposition.
As, therefore, we cannot go back to ante-
cedent propositions without end, the evi-
dence must at last rest upon propositions,
one or more, which have their evidence in
themselves — that is, upon first principles.

As to the evidence of our own existence,
and of the existence of a first cause, Mr
Locke does not say whether it rests upon
first principles or not. But it is manifest,
from what he has said upon both, that it
does. [646]

With regard to our own existence, says
he, we perceive it so plainly and so cer-
tainly that it neither needs nor is capable
of any proof. This is as much as to say
that our own existence is a first principle ;
for it is applying to this truth the very
definition of a first principle.

He adds, that, if I doubt, that very doubt
makes me perceive my own existence, and
will not suffer me to doubt of that. If I
feel pain, I have as certain perception of
my existence as of the pain I feel.

Here we have two first principles plainly
implied — First, That my feeling pain, or
being conscious of pain, is a certain evidence
of the real existence of that pain; and,
secondly, That pain cannot exist without a
mind or being that is pained. That these
are first principles, and incapable of proof,
Mr Locke acknowledges. And it is certain,
that, if they are not true, we can have no
evidence of our own existence • for if we
may feel pain when no pain really exists, or
if pain may exist without any being that is
pained, then it is certain that our feeling
pain can give us no evidence of our ex-

Thus, it appears that the evidence of our



own existence, according to the view that
Mr Locke gives of it, is grounded upon two
of those first principles which we had occa-
sion to mention.

If we consider the argument he has given
for the existence of a first intelligent cause,
it is no less evident that it is grounded upon
other two of them. The first, That what
begins to exist must have a cause of its ex-
istence ; and the second, That an unintelli-
gent and unthinking being cannot be the
cause of beings that are thinking and in-
telligent. Upon these two principles, he
argues, very convincingly, for the existence
of a first intelligent cause of things. And,
if these principles are not true, we can have
no proof of the existence of a first cause,
either from our own existence, or from the
existence of other things that fall within our
view. [647]

Another thing advanced by Mr Locke
upon this subject is, that no science is or
hath been built upon maxims.

Surely Mr Locke was not ignorant of
geometry, which hath been built upon
maxims prefixed to the elements, as far back
as we are able to trace it. * But, though
they had not been prefixed, which was a
matter of utility rather than necessity, yet
it must be granted that every demonstra-
tion in geometry is grounded either upon
propositions formerly demonstrated, or upon
self-evident principles.

Mr Locke farther says, that maxims are
not of use to help men forward in the ad-
vancement of the sciences, or new dis-
coveries of yet unknown truths ; that New-
ton, in the discoveries he has made in his
never-enough-to-be-admired book, has not
been assisted by the general maxims — what-
ever is, is ; or, the whole is greater than a
part ; or the like.

I answer, the first of these is, as was be-
fore observed, an identical trifling proposi-
tion, of no use in mathematics, or in any
Other science. The second is often used by
Newton, and by all mathematicians, and
many demonstrations rest upon it. In
general, Newton, as well as all other mathe-
maticians, grounds his demonstrations of
mathematical propositions upon the axioms
laid down by Euclid, or upon propositions
which have been before demonstrated by
help of those axioms. [648]

But it deserves to be particularly observed,
that Newton, intending, in the third book of
his " Principia," to give a more scientific
form' to the physical part of astronomy,
which he had at first composed in a popular
form, thought proper to follow the example
of Euclid, and to lay down first, in what he

* Compare Stewart's " Elements," ii. pp. 38, 43,
IPC On this subject, " satius est silere quam parum
dicere."— H.

Calls " Regulm Philosophandi," and in his
" Phenomena," the first principles which he
assumes in his reasoning.

Nothing, therefore, could have been more
unluckily adduoed by Mr Locke to support
his aversion to first principles, than the ex-
ample of Sir Isaac Newton, who, by laying
down the first principles upon which he rea-
sons in those parts of natural philosophy
which he cultivated, has given a stability to
that science which it never had before, and
which it will retain to the end of the world.

I am now to give some account of a philo-
sopher, who wrote expressly on the subject
of first principles, after Mr Locke.

Pere Burner, a French Jesuit, first pub-
lished his " Traile des premiers Veritez, et
de la Source de nos Jugements," in 8vo, if
I mistake not, in the year 1724. It was
afterwards published in folio, as a part of
his " Cours des. Sciences." Paris, 1732.

He defines first principles to be proposi-
tions so clear that they can neither be
proved nor combated by those that are more

The first source of first principles he men-
tions, is, that intimate conviction which
every man has of his own existence, and of
what passes in his own mind. Some philo-
sophers, he observes, admitted these as first
principles, who were unwilling to admit any
others ; and he shews the strange conse-
quences that follow from this system.

A second source of first principles he
makes to be common sense ; which, he ob-
serves, philosophers have not been wont to
consider. He defines it to be the disposi-
tion which Nature has planted in all men,
or the far greater part, which leads them,
when they come to the use of reason, to form
a common and uniform judgment upon
objects which are not objects of conscious-
ness, nor are founded on any antecedent
judgment. [649]

He mentions, not as a full enumeration,
but as a specimen, the following principles
of common sense.

1. That there are other beings and other
men in the universe, besides myself.

2. That there is in them something that
is called truth, wisdom, prudence ; and that
these things are not purely arbitrary.

3. That there is something in me which
1 call intelligence, and something which is
not that intelligence, which I call my body ;
and that these things have different pro-

4. That all men are not in a conspiracy
to deceive me and impose upon my cre-

5. That what has not intelligence cannot
produce the effects of intelligence, nor can
pieces of matter thrown together by chance
form any regular work, such as a clock 01



Lessay VI.

He explains very particularly the several
parts of his definition of common sense,
and shews how the dictates of common
sense may be distinguished from common
prejudices ; and then enters into a particular
consideration of the primary truths that
concern being in general ; the truths that
concern thinking beings ; those that concern
body ; and those on which the various
branches of human knowledge are grounded.
I shall not enter into a detail of his sen-
timents on these subjects. I think there is
more which I take to be original in this
treatise than in most books of the meta-
physical kind I have met with ; that many
of his notions are solid; and that others,
which I cannot altogether approve, are
ingenious. [650]

The other writers I have mentioned,
after Des Cartes, may, I think, -without
impropriety, be called Cartesians. For,
though they differ from Des Cartes in some
things, and contradict him in others, yet
they set«out from the same principles, and
follow the same method, admitting no other
first principle with regard to the existence
of things but their own existence, and the
existence of those operations of mind of
which they are conscious, and requiring
that the existence of a material world, and
the existence of other men and things,
should be proved by argument.

This method of philosophising is common
to Des Cartes, Malebranche, Arnauld,
Locke, Norris, Collier, Berkeley, and Hume ;
and, as it was introduced by Des Cartes, I
call it the Cartesian system, and those who
follow it Cartesians, not intending any dis-
respect by this term, but to signify a parti-
cular method of philosophising common to
them all, and begun by Des Cartes.

Some of these have gone the utmost
length in scepticism, leaving no existence
in nature but that of ideas and impressions.
Some have endeavoured to throw off the
belief of a material world only, and to leave
us ideas and spirits. All of them have
fallen into very gross paradoxes, which can
never sit easy upon the human understand-
ing, and which, though adopted in the
closet, men find themselves under a ne-
cessity of throwing off and disclaiming when
they enter into society.

Indeed, in my judgment, those who have
reasoned most acutely and consequentially
upon this system, are they that have gone
deepest into scepticism.

Father Buffier, however, is no Cartesian
in this sense. He seems to have perceived
the defects of the Cartesian system while
it was in the meridian of its glory, and to
have been aware that a ridiculous scepticism
is the natural issue of it, and therefore
nobly attempted to lay a broader founda-
tion for human knowledge, and has the

honour of being the first, as far as I know,
after Aristotle, who has given the world a
just treatise upon firtt principles. [651]

Some late writers, particularly Dr Os-
wald, Dr Beattie, and Dr Campbell, have
been led into a way of thinking somewhat
similar to that of Buffier ; the two former,
as I have reason to believe, without any in-
tercourse with one another, or any know-
ledge of what Buffier had wrote on the sub-
ject. Indeed, a man who thinks, and who
is acquainted with the philosophy of Mr
Hume, will very naturally be led to appre-
hend, that, to support the fabric of human
knowledge, some other principles are neces-
sary than those of Des Cartes and Mr
Locke. Buffier must be acknowledged to
have the merit of having discovered this,
before the consequences of the Cartesian
system were so fully displayed as they have
been by Mr Hume. But I am apt to think
that the man who does not see this now, -
must have but a superficial knowledge of
these subjects.*

The three writers above mentioned have
ray high esteem and affection as men 5 but
I intend to say nothing of them as writers
upon this subject, that I may not incur the
censure of partiality. Two of them have
been joined so closely with me in the anim-
adversions of a celebrated writer, -j- that
we may be thought too near of kin to give
our testimony of one another.



Our intellectual powers are wisely fitted
by the Author of our nature for the disco-
very of truth, as far as suits our present
state. Error is not their natural issue, any
more than disease is of the natural structure
of the body. Yet, as we are liable to vari-
ous diseases of body from accidental causes,
external and internal ; so we are, from like
causes, liable to wrong judgments. [652]

Medical writers have endeavoured to enu-
merate the diseases of the body, and to re-
duce them to a system, under the name of
nosology ; and it were to be wished that we
had also a nosology of the human under-

When we know a disorder of the body,
we are often at a loss to find the proper
remedy ; but in most cases the disorders of
the understanding point out their remedies
so plainly, that he who knows the one must
know the other.

Many authors have furnished useful ma-
terials for this purpose, and some have en-
deavoured to reduce them to a system. I

* See Note A H.

t Priestley.— H.



like best the general division given of them
by Lord Bacon, in his fifth book " De Aug-
mev.lis Scientiarum," and more fully treated
in his " Novum Organum." He divides
them into four classes — idola tribus, idola
specus, idola fori, and idola theairi. The
names are perhaps fanciful ; but I think
the division judicious, like most of the pro-
ductions of that wonderful genius. And as
this division was first made by him, he may
be indulged the privilege of giving names
to its several members.

I propose in this chapter to explain the
several members of this division, according
to the meaning of the author, and to give
instances of each, without confining myself
to those which Lord Bacon has given, and
without pretending to a complete enumera-

To every bias of the understanding, by which
a man may be misled in judging, or drawn
into error, Lord Bacon gives the name of
an idol. The understanding, in its natural
aud best state, pays its homage to truth
only. The causes of error are considered
by him as so many false deities, who receive
the homage which is due only to truth.

A. The first class are the idola tribus.
These are such as beset the whole human
species ; so that every man is in danger
from them. They arise from principles of
the human constitution, which are highly
useful and necessary in our present state ;
but, by their excess or defect, or wrong
direction, may lead us into error.

As the active principles of the human
frame are wisely contrived by the Author
of our being for the direction of our ac-
tions, and yet, without proper regulation
and restraint, are apt to lead us wrong, so
it is also with regard to those parts of our
constitution that have influence upon our
opinions. Of this we may take the follow-
ing instances : —

1. First, — Men are prone to be led too
much by authority in their opinions.

In the first part of life, we have no other
guide ; and, without a disposition to receive
implicitly what we are taught, we should
be incapable of instruction, and incapable
of improvement.

When judgment is ripe, there are many
things in which we are incompetent judges.
In such matters, it is most reasonable to
rely upon the judgment of those whom we
believe to be competent and disinterested.
The highest court of judicature in the
nation relies upon the authority of lawyers
and physicians in matters belonging to
their respective professions.

Even in matters which we have access
to know, authority alnays will have, and
ought to have, more or less weight, in pro-
portion to the evidence on which our own

judgment rests, and the opinion wc have of
the judgment and candour of those who
differ from us, or agree with us The
modest man, conscious of his own fal-
libility in judging, is in danger of giving
too much to authority ; the arrogant of
giving too little. [654]

In all matters belonging to our cog-
nizance, every man must be determined by
his own filial judgment, otherwise he does
not act the part of a rational being.

Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 105 of 114)