151. APPLICATION TO IMMEDIATE SENSE EVIDENCE.

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All

mediate evidence, therefore, depends ultimately for its value on

that of immediate evidence ; and of this we have two kinds :

immediate sense evidence for our interpretations of the immediate

data of sense experience, and immediate intellectual evidence

for abstract axioms of the ideal order. By the former class of

judgment we assert either (a] that some datum of sense ex-

1 C/. Science of Logic, ii., passim.

266 THEOR r OF KNO W LEDGE

perience (e.g. "this seen-and-felt datum ") exists, i.e. objectively

to ourselves perceiving it and as a reality independent of the

subjective perception process ; or (/;) also that it is such or such,

as the predicate-concept represents it to be (e.g. that it is " a

pen "). By the latter class of judgment we assert either (a) that

some abstract thought-object (e.g. " a whole ") is an objective

reality, a real possibility of actual existence, distinct as such from

our thinking, and not identical with, or a mere product or crea

tion of, our thinking ; or also (b] that it is such or such, as the

predicate-concept or thought-object represents it (e.g. that it is

"greater than its part"). 1

Now we say that the immediate, intrinsic, objective evidence

of what is present to the mind in such judgments is the ultimate

test of their truth or conformity with reality, and the ultimate

ground or motive of our certain assent to them. If this conten

tion be well-grounded, then it is plain that such evidence will

be also the supreme criterion of all truth and the ultimate

motive of all human certitude, inasmuch as all judgments to

which we assent on mediate evidence ultimately depend for their

truth or knowledge-value on those to which we assent on im

mediate evidence. But to show that the contention is well-

grounded we must understand clearly what it implies, and what

it does not imply.

(4) Let us take first the case of immediate sense evidence.

By this we are to understand not the mere presentation of a

datum to sense consciousness, but its presentation to intellect

through sense perception. For since truth or knowledge proper

is attained only through the intellectual act of interpretation or

judgment, the evidence which is a criterion of the truth of the

judgment, and a motive of our assent to the judgment, must be

always a characteristic of that which is presented to the intellect

for interpretation. Sense evidence is therefore a characteristic

of the sense datum as presented to and apprehended by the in

tellect. Now we have already shown - that this datum can

present itself to intellect through sense with characteristics (of

"actual existence," "externality" or " otherness," " extensity,"

"shape," "colour," "taste," etc.) which (i) compel the intellect to

Or such judgments may be negative: e.g. "There is no fireplace in this

room "; " This paper is not blue " ; " Two and two are not five " ; " Two straight

lines cannot enclose a space ".

2 Chaps, xiv.-xxi., especially 105, 109, 115, 122, 123, 127, 128.

TRUTH AND EVIDENCE 267

judge directly and spontaneously that the datum appears to " exist "

(independently of the cognitive process), to be "external,"

"material," "coloured," etc.; and which (2) can be seen by

intellectual reflection on the whole cognitive process and its

content to be such that those characteristics adequately ground

and guarantee the truth of the reflex judgment that the datum is

really what the spontaneous judgment pronounced it to be. But

in vindicating the claims of such evidence to justify these con

clusions a number of points must be noted.

First, the object apprehended by the judgment being a re

lation of real identity or non-identity, or, in other words, the

judgment being a representation of the presented real datum

through the medium of such a relation, the objective evidence

in this datum is an apprehended quality or characteristic in it

which grounds this relation, or what we have called an " onto-

logical exigency " which demands that the datum be intellectually

represented through the assertion of such a relation.

Secondly, even the direct, spontaneous judgment involves the

use of abstract intellectual concepts as predicates ("existence,"

"externality," "extensity," "colour," etc., etc.), and their appli

cation to the datum apprehended in the concrete as subject.

Therefore the reflex or philosophical justification of the real truth-

claim of the direct judgment rests on the evidence whereby we

have justified the thesis of Moderate Realism that those abstract

concepts are derived from the concrete sense data, and are formed

according to the apprehended real or ontological exigencies of

the sense data. 1 We have already shown that while the form

of intellectual conception, i.e. the fact that the continuously

presented stream or manifold of sense data is apprehended in the

form of abstract and universal concepts, simple and complex,

transcendental, generic and specific, is determined by the nature

of the human intellect as a power of " abstractive " cognition, the

matter of its concepts is determined by the nature of the sense

manifold in which this matter is seen to be embodied.

Thirdly, although the process by which the intellect forms its

complex concepts from simpler factors, pronouncing such com

plexes to be real and objective possibilities of existence, and the

process by which it applies them to actual sense data to interpret

these latter as actual existences, are both conducted under the

1 Cf. what was said above concerning the " real affinities " of the factors of our

intellectual concepts, vol. i., 88, 89, 91.

268 THEORY OF KNOWLEDGE

influence of what appears to be objective evidence, or to be in

other words the real nature of the presented realities, nevertheless

the intellect is liable to error in both processes. Leaving the

fallibility of the former process for consideration below, let us fix

our attention on the latter process : that by which we form such

judgments as " This is a flower " ; " This flower is a rose " ; " This

rose is red," etc. Now since, as we saw in dealing with sense

perception, we may, from a variety of causes (cf. 118), be mis

taken in such immediate spontaneous judgments, the question

arises whether or under what conditions the "sense evidence"

of what athing(7//mrj-can be a sufficient ground for judging what

the thing really is, or a sufficient motive for certain assent to such

a judgment as true. And the further question also arises, whether

what the thing appears can ever be an infallible test of the truth of

the judgment as to what the thing really is, and a cogent or com

pelling motive of assent to this judgment.

The answer to the first question is in the affirmative, but

with these qualifications : provided we have by reflection con

vinced ourselves that in the case in point our perception is

normal and accurate ; provided all the conditions, organic and

external, for accurate perception are verified ; provided the

mutually corrective and corroborative information of all the

senses that can subserve the judgment have been actually availed

of. 1 If a person neglect the safeguards thus furnished by re

flection, if he be unaware of their necessity, if through whatsoever

cause he fail to make use of them, he is liable to mistake ap

parent evidence for real evidence, and thus to err in assenting to

what he thinks to be a self-evident judgment of sense perception.

And it may even happen that on the one hand, whether through

inexperience or inadvertence, he may be at the time unable to

avail of those safeguards, while on the other hand the apparent

evidence may be such as there and then to compel his assent.

Hence we have to recognize that there are errors which, for the

time and for individual human minds, are inevitable (cf. 16).

1 Should we add also : "provided the observer has convinced himself that his

spontaneous belief in the trustworthiness of his senses is philosophically justified" ?

No ; not in the sense that he must have made a systematic study of this whole

epistemological problem ; but only in the sense that should he happen to have en

countered from any source any apparently serious reasons for doubt or misgiving as

to the general trustworthiness of normal sense perception, he must of course have

succeeded in convincing himself that those reasons were only apparent and not real

reasons for doubting.

TRUTH AND EVIDENCE 269

But in the faculty of intellectual reflection the human mind has

the means of correcting such errors.

The answer to the second question is that when reflection has

convinced us that our actual perception is normal and accurate,

i.e. endowed with all the conditions requisite for trustworthiness,

the evidence (of what the thing appears to be) persists often,

and, indeed, as a general rule, so clear as to be a cogent or com

pelling motive of assent to the judgment that the thing really is

such or such. When it does remain thus cogent it is an infallible

test of truth in the sense that the intellect cannot be the victim of

an illusion in yielding to it. The reflective process, whereby the

observer judges that all the conditions of normal perception are

present in the particular case, is of course dependent not merely

on the evidence that the present perception is normal, but also

on the evidence of what constitutes normal sense experience in

himself and others. And although there can be cases in which

he may err in forming this reflective, justifying judgment, there

are certainly cases, and they are the generality of cases, in

which the evidence for this judgment is so clearly cogent that

he cannot be mistaken in interpreting his present sense perception

as giving him certain knowledge that " this thing is really what

it appears to him " . We may say, therefore, that although the

human mind is fallible in its interpretation of sense evidence, i.e.

although the individual observer may err accidentally in judging

that things really are as they appear ; and although there are even

cases in which such error is for the time inevitable; nevertheless

there are cases in which error is impossible, i.e. in which all the

conditions of normal and trustworthy -perception are so clearly

present that it is physically impossible for the observer to mis

interpret the sense datum. 1

To this, however, it may be objected that the individual ob

server is never compelled by the evidence to formulate or accept

such a judgment as e.g. " This rose is really red," but only such

a judgment as "This rose appears red to all normal sense percep-

1 We say " physically impossible," because in any individual perception the

Author of Nature may, for a higher, moral purpose, miraculously modify the normal

physical appearances on which our interpretations of the extramental reality and

nature of sense data are based. The consequent accidental deception of the indi

vidual is therefore metaphysically possible. But universal sense deception would be

metaphysically impossible, because purposeless and incompatible with the Divine

Wisdom and Veracity. Cf. supra, 123. Science of Logic, ii., 224, pp. 100-2,

112-13; 250, pp. 220 i.

270 THE OR Y OF KNO W LEDGE

tion" (cf. 119, 123, 126). The reply of the ordinary man would

be something to this effect : " It is just precisely because (i) this

rose appears red to me, and because (2) I know my own percep

tion to be normal, and this rose to appear red to all other possible

normal perceivers, that I feel not only justified but compelled to

judge that this rose is really red ". In other words the cogency or

compelling force of sense appearances as evidence of reality can per

sist throughout the reflective process by which the intellect tests

and determines the real evidential or truth-revealing value of

these appearances. 1 The difficulties raised by sensists, phen-

omenists, or idealists, against the real validity of sense evidence

cannot affect its natural cogency. Either these difficulties are

seen to be really groundless and frivolous, in which case the

irresistibly formed spontaneous judgment of perception is philo

sophically justified ; or else such difficulties will seem insuperable,

in which case also the spontaneous judgment will continue to

assert itself as a practical principle of action in spite of the

supervening theoretical scepticism.

We may say, then, that the immediate evidence of actual

normal sense perception is for the individual a sufficient criterion

of the truth of the spontaneous judgments suggested by it, and

an adequate motive for physical certitude as to the truth of those

judgments. We are liable to misinterpret sense evidence, i.e. to

be misled by appearances. Experience of such mistakes will

teach us that not all apparent sense evidence is real evidence,

but only such sense evidence as fulfils certain conditions which

can be discovered by reflection on our past experiences. In

other words our perception must be normal in order that its evi

dence be trustworthy. This, however, does not mean that ex

plicit knowledge of its conformity with other people s perceptions

is a prerequisite of our accepting it as trustworthy ; nor does it

mean that such conformity is the test of its trustworthiness

(126): for if the evidence furnished by the individual s own

sense perception did not of itself guarantee the truth of his

spontaneous interpretations of his sense data neither could any

cumulation of such evidences guarantee it, apart from the fact

that it is only on the evidence of his own sense perceptions that

he knows of the distinct and independent existence of other

1 It is this cogency, or vis insuperabilis, which persists on reflection, that

JF.ANNIKRK sets down as one of the characteristics by which we can discern evidence

to be real op. cil., p. 252.

TR UTH AND E VIDENCE 2 7 1

human beings. It only means that his spontaneous interpreta

tion of a particular portion of his sense experience, as revealing to

him other men having experiences similar to his own, helps him

to determine the conditions under which his own perceptions will

be trustworthy ; l and that the experienced conformity of his

own perceptions with those of other people will be for him a

confirming criterion of the trustworthiness of his own sense per

ceptions.

Finally it may be noted that when we claim for immediate

sense evidence the prerogative of being the supreme criterion of

the truth of our conviction that a material universe exists in time

and space independently of our perception of it, and the ultimate

motive of our certitude as to the truth of that conviction, we do

not make this claim for immediate sense evidence in itself, in

isolation from the evidence we have for the validity of our intel

lectual concepts, and for the truth of rational principles of the ideal

order. From our treatment of the general problem of sense per

ception 2 it will be clear that the conviction 3 is philosophically

justified only by what we may perhaps appropriately describe as

the intellectual interpretation or rationalization of sense evidence

by the evidence of necessary principles of the ideal order. The

claim of this latter evidence to be, therefore, in ultimate analysis,

the supreme criterion of truth and the ultimate motive of human

certitude, we must now briefly examine.