The mind directly perceives nothing but its own ideas, but it seeks a
knowledge of things! If this is possible it can only be indirect
knowledge--the mind knows things through its ideas, and possesses criteria
which show that its ideas agree with things.
Two cases must be clearly distinguished, for a considerable number of our
ideas, viz., all complex ideas except those of substances, make no claim
to represent things, and consequently cannot represent them falsely. For
mathematical and moral ideas and principles, and the truth thereof, it is
entirely immaterial whether things and conditions correspondent to them
exist in nature or not. They are valid, even if nowhere actualized; they
are "eternal truths," not in the sense that they are known from childhood,
but in the sense that, as soon as known, they are immediately assented
to.[1] The case is different, however, with simple ideas and the ideas of
substances, which have their originals without the mind and which are to
correspond with these. In regard to the former we may always be certain
that they agree with real things, for since the mind can neither
voluntarily originate them (_e.g._, cannot produce sensations of color
in the dark) nor avoid having them at will, but only receive them from
without, they are not creatures of the fancy, but the natural and regular
productions of external things affecting us. In regard to the latter, the
ideas of substances, we may be certain at least when the simple ideas which
compose them have been found so connected in experience.
Perception has
an external cause, whose influence the mind is not able to withstand. The
mutual corroboration furnished by the reports of the different senses, the
painfulness of certain sensations, the clear distinction between ideas from
actual perception and those from memory, the possibility of producing and
predicting new sensations of an entirely definite nature in ourselves and
in others, by means of changes which we effect in the external world (e.g.
by writing down a word)--these give further justification for the trust
which we put in the senses. No one will be so skeptical as to doubt in
earnest the existence of the things which he sees and touches, and to
declare his whole life to be a deceptive dream. The certitude which
perception affords concerning the existence of external objects is indeed
not an absolute one, but it is sufficient for the needs of life and the
government of our actions; it is "as certain as our happiness or misery,
beyond which we have no concernment, either of knowing or being." In regard
to the past the testimony of the senses is supplemented by memory, in
which certainty [in regard to the continued existence of things previously
perceived] is transformed into high probability; while in regard to the
existence of other finite spirits, numberless kinds of which may be
conjectured to exist, though their existence is quite beyond our powers of
perception, certitude sinks into mere (though well-grounded) faith.
[Footnote 1: Thus it results that knowledge, although dependent on
experience for all its materials, extends beyond experience. The
understanding is completely bound in the reception of simple ideas; less so
in the combination of these into complex ideas; absolutely free in the act
of comparison, which it can omit at will; finally, again, completely bound
in its recognition of the relation in which the ideas it has chosen
to compare stand to one another. There is room for choice only in the
intermediate stage of the cognitive process; at the beginning (in the
reception of the simple ideas of perception, a, b, c, d), and at the end
(in judging how the concepts a b c and a b d stand related to each other),
the understanding is completely determined.]
More certain than our _sensitive_ knowledge of the existence of external
objects, are our immediate or _intuitive_ knowledge of our own existence
and our mediate or _demonstrative_ knowledge of the existence of God.
Every idea that we have, every pain, every thought assures us of our own
existence. The existence of God, however, as the infinite cause of all
reality, endowed with intelligence, will, and supreme power, is inferred
from the existence and constitution of the world and of ourselves. Reality
exists; the real world is composed of matter in motion and thinking beings,
and is harmoniously ordered. Since it is impossible for any real being to
be produced by nothing, and since we obtain no satisfactory answer to the
question of origin until we rise to something existent from all eternity,
we must assume as the cause of that which exists an Eternal Being, which
possesses in a higher degree all the perfections which it has bestowed upon
the creatures. As the cause of matter and motion, and as the source of all
power, this Being must be omnipotent; as the cause of beauty and order in
the world, and, above all, as the creator of thinking beings, it must be
omniscient. But these perfections are those which we combine in the idea
of God.
Intuitive knowledge is the highest of the three degrees of knowledge. It is
gained when the mind perceives the agreement or disagreement of two ideas
at first sight, without hesitation, and without the intervention of any
third idea. This immediate knowledge is self-evident, irresistible, and
exposed to no doubt. Knowledge is demonstrative when the mind perceives the
agreement (or disagreement) of two ideas, not by placing them side by side
and comparing them, but through the aid of other ideas.
The intermediate
links are called proofs; their discovery is the work of the reason, and
quickness in finding them out is termed sagacity. The greater the number
of the intermediate steps, the more the clearness and distinctness of the
knowledge decreases, and the more the possibility of error increases.
In order for an argument (_e. g_., that a = d) to be conclusive, every
particular step in it (a = b, b = c, c = d) must possess intuitive
certainty. Mathematics is not the only example of demonstrative knowledge,
but the most perfect one, since in mathematics, by the aid of visible
symbols, the full equality and the least differences among ideas may be
exactly measured and sharply determined.
Besides real existence Locke, unsystematically enough, enumerates three
other sorts of agreement between ideas,--in the perception of which he
makes knowledge consist,--viz., identity or diversity (blue is not yellow),
relation (when equals are added to equals the results are equal), and
coexistence or necessary connexion (gold is fixed). We are best off in
regard to the knowledge of the first of these, "identity or diversity," for
here our intuition extends as far as our ideas, since we recognize every
idea, as soon as it arises, as identical with itself and different from
others. We are worst off in regard to "necessary connexion." We know
something, indeed, concerning the incompatibility or coexistence of certain
properties (_e. g_., that the same object cannot have two different sizes
or colors at the same time; that figure cannot exist apart from extension):
but it is only in regard to a few qualities and powers of bodies that we
are able to discover dependence and necessary connexion by intuitive or
demonstrative thought, while in most cases we are dependent on experience,
which gives us information concerning particular cases only, and affords no
guarantee that things are the same beyond the sphere of our observation and
experiment. Since empirical inquiry furnishes no certain and universal
knowledge, and since the assumption that like bodies will in the same
circumstances have like effects is only a conjecture from analogy, natural
science in the strict sense does not exist. Both mathematics and ethics,
however, belong in the sphere of the demonstrative knowledge of relations.
The principles of ethics are as capable of exact demonstration as those of
arithmetic and geometry, although their underlying ideas are more complex,
more involved, hence more exposed to misunderstanding, and lacking in
visible symbols; though these defects can, and should, in part be made good
by careful and strictly consistent definitions. Such moral principles as
"where there is no property there is no injustice," or
"no government
allows absolute liberty," are as certain as any proposition in Euclid.
The advantage of the mathematical and moral sciences over the physical
sciences consists in the fact that, in the former, the real and nominal
essences of their objects coincide, while in the latter they do not; and,
further, that the real essences of substances are beyond our knowledge. The
true inner constitution of bodies, the root whence all their qualities, and
the coexistence of these, necessarily proceed, is completely unknown to us;
so that we are unable to deduce them from it.
Mathematical and moral ideas,
on the other hand, and their relations, are entirely accessible, for they
are the products of our own voluntary operations. They are not copied from
things, but are archetypal for reality and need no confirmation from
experience. The connexion constituted by our understanding between the
ideas crime and punishment _(e. g_., the proposition: crime deserves
punishment) is valid, even though no crime had ever been committed, and
none ever punished. Existence is not at all involved in universal
propositions; "general knowledge lies only in our own thoughts, and
consists barely in the contemplation of our own abstract ideas" and their
relations. The truths of mathematics and ethics are both universal and
certain, while in natural science single observations and experiments are
certain, but not general, and general propositions are only more or less
probable. Both the particular experiments and the general conclusions are
of great value under certain circumstances, but they do not meet the
requirements of comprehensive and certain knowledge.
The _extent_ of our knowledge is very limited--much less, in fact, than
that of our ignorance. For our knowledge reaches no further than our ideas,
and the possibility of perceiving their agreements. Many things exist of
which we have no ideas--chiefly because of the fewness of our senses and
their lack of acuteness--and just as many of which our ideas are only
imperfect. Moreover, we are often able neither to command the ideas
which we really possess, or at least might attain, nor to perceive their
connexions. The ideas which are lacking, those which are undiscoverable,
those which are not combined, are the causes of the narrow limits of human
knowledge.
There are two ways by which knowledge may be extended: by experience, on
the one hand, and, on the other, by the elevation of our ideas to a state
of clearness and distinctness, together with the discovery and systematic
arrangement of those intermediate ideas which exhibit the relation of other
ideas, in themselves not immediately comparable. The syllogism, as an
artificial form, is of little value in the perception of the agreements
between these intermediate and final terms, and of none whatever in the
discovery of the former. Analytical and identical propositions which merely
explicate the conception of the subject, but express nothing not already
known, are, in spite of their indefeasible certitude, valueless for the
extension of knowledge, and when taken for more than verbal explanations,
mere absurdities. Even those most general propositions, those "principles"
which are so much talked of in the schools, lack the utility which is so
commonly ascribed to them. Maxims are, it is true, fit instruments for the
communication of knowledge already acquired, and in learned disputations
may perform indispensable service in silencing opponents, or in bringing
the dispute to a conclusion; but they are of little or no use in the
discovery of new truth. It is a mistake to believe that special cases (as
5 = 2 + 3, or 5 = 1 + 4) are dependent on the truth of the abstract rule
(the whole is equal to the sum of its parts), that they are confirmed by
it and must be derived from it. The particular and concrete is not only
as clear and certain as the general maxim, but better known than this,
as well as earlier and more easily perceived. Nay, further, in cases
where ideas are confused and the meanings of words doubtful, the use of
axioms is dangerous, since they may easily lend the appearance of proved
truth to assertions which are really contradictory.
Between the clear daylight of certain knowledge and the dark night of
absolute ignorance comes the twilight of probability. We find ourselves
dependent on _opinion_ and presumption, or judgment based upon probability,
when experience and demonstration leave us in the lurch and we are,
nevertheless, challenged to a decision by vital needs which brook no delay.
The judge and the historian must convince themselves from the reports of
witnesses concerning events which they have not themselves observed; and
everyone is compelled by the interests of life, of duty, and of eternal
salvation to form conclusions concerning things which lie beyond the limits
of his own perception and reflective thought, nay, which transcend all
human experience and rigorous demonstration whatever. To delay decision and
action until absolute certainty had been attained, would scarcely allow
us to lift a single finger. In cases concerning events in the past, the
future, or at a distance, we rely on the testimony of others (testing their
reports by considering their credibility as witnesses and the conformity of
the evidence to general experience in like cases); in regard to questions
concerning that which is absolutely beyond experience, _e.g._, higher
orders of spirits, or the ultimate causes of natural phenomena, analogy is
the only help we have. If the witnesses conflict among themselves, or with
the usual course of nature, the grounds _pro_ and _con_
must be carefully
balanced; frequently, however, the degree of probability attained is so
great that our assent is almost equivalent to complete certainty. No
one doubts,--although it is impossible for him to
"know,"--that Caesar
conquered Pompey, that gold is ductile in Australia as elsewhere, that iron
will sink to-morrow as well as to-day. Thus opinion supplements the lack of
certain knowledge, and serves as a guide for belief and action, wherever
the general lot of mankind or individual circumstances prevent absolute
certitude.
Although in this twilight region of opinion demonstrative proofs are
replaced merely by an "occasion" for "taking" a given fact or idea "as true
rather than false," yet assent is by no means an act of choice, as the
Cartesians had erroneously maintained, for in knowledge it is determined by
clearly discerned reasons, and in the sphere of opinion, by the balance of
probability. The understanding is free only in combining ideas, not in its
judgment concerning the agreement or the repugnancy of the ideas compared;
it lies within its own power to decide whether it will judge at all, and
what ideas it will compare, but it has no control over the result of the
comparison; it is impossible for it to refuse its assent to a demonstrated
truth or a preponderant probability.
In this recognition of objective and universally valid relations existing
among ideas, which the thinking subject, through comparisons voluntarily
instituted, discovers valid or finds given, but which it can neither alter
nor demur to, Locke abandons empirical ground (cf. p.
155) and approaches
the idealists of the Platonizing type. His inquiry divides into two very
dissimilar parts (a psychological description of the origin of ideas and a
logical determination of the possibility and the extent of knowledge), the
latter of which is, in Locke's opinion, compatible with the former, but
which could never have been developed from it. The rationalistic edifice
contradicts the sensationalistic foundation. Locke had hoped to show the
value and the limits of knowledge by an inquiry into the origin of ideas,
but his estimate of this value and these limits cannot be proved from the
_a posteriori_ origin of ideas--it can only be maintained in despite of
this, and stands in need of support from some (rationalistic) principle
elsewhere obtained. Thinkers who trace back all simple ideas to outer and
inner perception we expect to reject every attempt to extend knowledge
beyond the sphere of experience, to declare the combinations of ideas
which have their origin in sensation trustworthy, and those which are
formed without regard to perception, illusory; or else, with Protagoras,
to limit knowledge to the individual perceiving subject, with a consequent
complete denial of its general validity. But exactly the opposite of all
these is found in Locke. The remarkable spectacle is presented of a
philosopher who admits no other sources of ideas than perception and the
voluntary combination of perceptions, transcending the limits of experience
with proofs of the divine existence, viewing with suspicion the ideas of
substance formed at the instance of experience, and reducing natural
science to the sphere of mere opinion; while, on the other hand, he
ascribes reality and eternal validity to the combinations of ideas formed
independently of perception, which are employed by mathematics and ethics,
and completely abandons the individualistic position in his naïve faith in
the impregnable validity of the relations of ideas, which is evident to all
who turn their attention to them. The ground for the universal validity of
the relations among ideas as well as of our knowledge of them, naturally
lies not in their empirical origin (for my experience gives information to
me alone, and that only concerning the particular case in question), but in
the uniformity of man's rational constitution. If two men really have the
same ideas--not merely think they have because they use similar
language--it is impossible, according to Locke, that they should hold
different opinions concerning the relation of their ideas. With this
conviction, that the universal validity of knowledge is rooted in the
uniformity of man's rational constitution, and the further one, that we
attain certain knowledge only when things conform to our ideas, Locke
closely approaches Kant; while his assumption of a fixed order of relations
among ideas, which the individual understanding cannot refuse to recognize,
and the typical character assigned to mathematics, associate him with
Malebranche and Spinoza. In view of these points of contact with the
rationalistic school and his manifold dependence on its founder, we may
venture the paradox, that Locke may not only be termed a Baconian with
Cartesian leanings, but (almost) a Cartesian influenced by Bacon. The
possibility must not be forgotten, however, that rationalistic suggestions
came to him also from Galileo, Hobbes, and Newton.[1]
[Footnote 1: Cf. the article by Benno Erdmann cited p.
156, note.]
Intermediate between knowledge and opinion stands faith as a form of assent
which is based on testimony rather than on deductions of the reason,
but whose certitude is not inferior to that of knowledge, since it is a
communication from God, who can neither deceive nor be deceived. Faith
and the certainty thereof depend on reason, in so far as reason alone can
determine whether a divine revelation has really been made and the meaning
of the words in which the revelation has come down to us. In determining
the boundaries of faith and reason Locke makes use of the
distinction--which has become famous--between things above reason,
according to reason, and contrary to reason. Our conviction that God exists
is according to reason; the belief that there are more gods than one, or
that a body can be in two different places at the same time, contrary
to reason; the former is a truth which can be demonstrated on rational
grounds, the latter an assumption incompatible with our clear and distinct
ideas. In the one case revelation confirms a proposition of which we
were already certain; in the other an alleged revelation is incapable
of depriving our certain knowledge of its force. Above reason are those
principles whose probability and truth cannot be shown by the natural use
of our faculties, as that the dead shall rise again and the account of the
fall of part of the angels. Among the things which are not contrary to
reason belong miracles, for they contradict opinion based on the usual
course of nature, it is true, but not our certain knowledge; in spite of
their supernatural character they deserve willing acceptance, and receive
it, when they are well attested, whereas principles contrary to reason must
be unconditionally rejected as a revelation from God.
Locke's demand for
the subjection of faith to rational criticism assures him an honorable
place in the history of English deism. He enriched the philosophy of
religion by two treatises of his own: _The Reasonableness of Christianity_,
1695, and three _Letters on Tolerance_, 1689-1692. The former transfers the
center of gravity of the Christian religion from history to the doctrine of
redemption; the _Letters_ demand religious freedom, mutual tolerance among
the different sects, and the separation of Church and State. Those sects
alone are to receive no tolerance which themselves exercise none, and which
endanger the well-being of society; together with atheists, who are
incapable of taking oaths. In other respects it is the duty of the state to
protect all confessions and to favor none.
%(b) Practical Philosophy.%--Locke contributed to practical philosophy
important suggestions concerning freedom, morality, politics, and
education. Freedom is the "power to begin or forbear, continue or put an
end to" actions (thoughts and motions). It is not destroyed by the fact
that the will is always moved by desire, more exactly, by uneasiness under
present circumstances, and that the decision is determined by the judgment
of the understanding. Although the result of examination is itself
dependent on the unalterable relations of ideas, it is still in our power
to decide whether we will consider at all, and what ideas we will take into
consideration. Not the thought, not the determination of the will, is free,
but the person, the mind; this has the power to suspend the prosecution of
desire, and by its judgment to determine the will, even in opposition
to inclination. Four stages must, consequently, be distinguished in the
volitional process: desire or uneasiness; the deliberative combination of
ideas; the judgment of the understanding; determination.
Freedom has its
place at the beginning of the second stage: it is open to me to decide
whether to proceed at all to consideration and final judgment concerning a
proposed action; thus to prevent desire from directly issuing in movements;
and, according to the result of my examination, perhaps, to substitute for
the act originally desired an opposite one. Without freedom, moral judgment
and responsibility would be impossible. The above appears to us to
represent the essence of Locke's often vacillating discussion of freedom
(II. 21). Desire is directed to pleasure; the will obeys the understanding,
which is exalted above motives of pleasure and the passions. Everything is
physically good which occasions and increases pleasure in us, which removes
or diminishes pain, or contributes to the attainment of some other good and
the avoidance of some other evil. Actions, on the contrary, are morally
good when they conform to a rule by which they are judged. Whoever
earnestly meditates on his welfare will prefer moral or rational good to