1. Treating of Words necessary to Knowledge.
THOUGH the examining and judging of ideas by themselves, their names
being quite laid aside, be the best and surest way to clear and distinct
knowledge: yet, through the prevailing custom of using sounds for ideas,
I think it is very seldom practised. Every one may observe how common it
is for names to be made use of, instead of the ideas themselves, even
when men think and reason within their own breasts; especially if the
ideas be very complex, and made up of a great collection of simple ones.
This makes the consideration of WORDS and PROPOSITIONS so necessary
a part of the Treatise of Knowledge, that it is very hard to speak
intelligibly of the one, without explaining the other.
2. General Truths hardly to be understood, but in verbal Propositions.
All the knowledge we have, being only of particular or general truths,
it is evident that whatever may be done in the former of these, the
latter, which is that which with reason is most sought after, can never
be well made known, and is very seldom apprehended, but as conceived
and expressed in words. It is not, therefore, out of our way, in the
examination of our knowledge, to inquire into the truth and certainty of
universal propositions.
3. Certainty twofold--of Truth and of Knowledge.
But that we may not be misled in this case by that which is the danger
everywhere, I mean by the doubtfulness of terms, it is fit to observe
that certainty is twofold: CERTAINTY OF TRUTH and CERTAINTY OF
KNOWLEDGE. Certainty of truth is, when words are so put together in
propositions as exactly to express the agreement or disagreement of the
ideas they stand for, as really it is. Certainty of knowledge is to
perceive the agreement or disagreement of ideas, as expressed in any
proposition. This we usually call knowing, or being certain of the truth
of any proposition.
4. No Proposition can be certainly known to be true, where the real
Essence of each Species mentioned is not known.
Now, because we cannot be certain of the truth of any general
proposition, unless we know the precise bounds and extent of the species
its terms stand for, it is necessary we should know the essence of each
species, which is that which constitutes and bounds it.
This, in all simple ideas and modes, is not hard to do. For in these
the real and nominal essence being the same, or, which is all one, the
abstract idea which the general term stands for being the sole essence
and boundary that is or can be supposed of the species, there can be no
doubt how far the species extends, or what things are comprehended under
each term; which, it is evident, are all that have an exact conformity
with the idea it stands for, and no other. But in substances, wherein
a real essence, distinct from the nominal, is supposed to constitute,
determine, and bound the species, the extent of the general word is very
uncertain; because, not knowing this real essence, we cannot know what
is, or what is not of that species; and, consequently, what may or may
not with certainty be affirmed of it. And thus, speaking of a MAN,
or GOLD, or any other species of natural substances, as supposed
constituted by a precise and real essence which nature regularly imparts
to every individual of that kind, whereby it is made to be of that
species, we cannot be certain of the truth of any affirmation or
negation made of it. For man or gold, taken in this sense, and used
for species of things constituted by real essences, different from the
complex idea in the mind of the speaker, stand for we know not what; and
the extent of these species, with such boundaries, are so unknown and
undetermined, that it is impossible with any certainty to affirm, that
all men are rational, or that all gold is yellow. But where the nominal
essence is kept to, as the boundary of each species, and men extend the
application of any general term no further than to the particular things
in which the complex idea it stands for is to be found, there they are
in no danger to mistake the bounds of each species, nor can be in doubt,
on this account, whether any proposition be true or not. I have chosen
to explain this uncertainty of propositions in this scholastic way, and
have made use of the terms of ESSENCES, and SPECIES, on purpose to show
the absurdity and inconvenience there is to think of them as of any
other sort of realities, than barely abstract ideas with names to them.
To suppose that the species of things are anything but the sorting of
them under general names, according as they agree to several abstract
ideas of which we make those names signs, is to confound truth, and
introduce uncertainty into all general propositions that can be made
about them. Though therefore these things might, to people not possessed
with scholastic learning, be treated of in a better and clearer way
yet those wrong notions of essences or species having got root in most
people's minds who have received any tincture from the learning which
has prevailed in this part of the world, are to be discovered and
removed, to make way for that use of words which should convey certainty
with it.
5. This more particularly concerns Substances.
The names of substances, then, whenever made to stand for species which
are supposed to be constituted by real essences which we know not, are
not capable to convey certainty to the understanding. Of the truth
general propositions made up of such terms we cannot be sure. [The
reason whereof is plain: for how can we be sure that this or that
quality is in gold, when we know not what is or is not gold? Since in
this way of speaking, nothing is gold but what partakes of an essence,
which we, not knowing, cannot know where it is or is not, and so cannot
be sure that any parcel of matter in the world is or is not in this
sense gold; being incurably ignorant whether IT has or has not that
which makes anything to be called gold; i. e. that real essence of gold
whereof we have no idea at all. This being as impossible for us to know
as it is for a blind man to tell in what flower the colour of a pansy is
or is not to be found, whilst he has no idea of the colour of a pansy at
all. Or if we could (which is impossible) certainly know where a real
essence, which we know not, is, v.g. in what parcels of matter the real
essence of gold is, yet could we not be sure that this or that quality
could with truth be affirmed of gold; since it is impossible for us to
know that this or that quality or idea has a necessary connexion with
a real essence of which we have no idea at all, whatever species that
supposed real essence may be imagined to constitute.]
6.
On the other side, the names of substances, when made use of as they
should be, for the ideas men have in their minds, though they carry a
clear and determinate signification with them, will not yet serve us to
make many universal propositions of whose truth we can be certain. Not
because in this use of them we are uncertain what things are signified
by them, but because the complex ideas they stand for are such
combinations of simple ones as carry not with them any discoverable
connexion or repugnancy, but with a very few other ideas.
7.
The complex ideas that our names of the species of substances properly
stand for, are collections of such qualities as have been observed to
co-exist in an unknown substratum, which we call substance; but what
other qualities necessarily co-exist with such combinations, we cannot
certainly know, unless we can discover their natural dependence; which,
in their primary qualities, we can go but a very little way in; and in
all their secondary qualities we can discover no connexion at all: for
the reasons mentioned, chap. iii. Viz. 1. Because we know not the
real constitutions of substances, on which each secondary quality
particularly depends. 2. Did we know that, it would serve us only for
experimental (not universal) knowledge; and reach with certainty no
further than that bare instance: because our understandings can
discover no conceivable connexion between any secondary quality and any
modification whatsoever of any of the primary ones. And therefore there
are very few general propositions to be made concerning substances,
which can carry with them undoubted certainty.
8. Instance in Gold.
'All gold is fixed,' is a proposition whose truth we cannot be certain
of, how universally soever it be believed. For if, according to the
useless imagination of the Schools, any one supposes the term gold to
stand for a species of things set out by nature, by a real essence
belonging to it, it is evident he knows not what particular substances
are of that species; and so cannot with certainty affirm anything
universally of gold. But if he makes gold stand for a species determined
by its nominal essence, let the nominal essence, for example, be the
complex idea of a body of a certain yellow colour, malleable, fusible,
and heavier than any other known;--in this proper use of the word gold,
there is no difficulty to know what is or is not gold. But yet no other
quality can with certainty be universally affirmed or denied of gold,
but what hath a DISCOVERABLE connexion or inconsistency with that
nominal essence. Fixedness, for example, having no necessary connexion
that we can discover, with the colour, weight, or any other simple
idea of our complex one, or with the whole combination together; it is
impossible that we should certainly know the truth of this proposition,
that all gold is fixed.
9. No discoverable necessary connexion between nominal essence gold, and
other simple ideas.
As there is no discoverable connexion between fixedness and the colour,
weight, and other simple ideas of that nominal essence of gold; so,
if we make our complex idea of gold, a body yellow, fusable, ductile,
weighty, and fixed, we shall be at the same uncertainty concerning
solubility in AQUA REGIA, and for the same reason. Since we can never,
from consideration of the ideas themselves, with certainty affirm or
deny of a body whose complex idea is made up of yellow, very weighty,
ductile, fusible, and fixed, that it is soluble in AQUA REGIA: and so
on of the rest of its qualities. I would gladly meet with one general
affirmation concerning any will, no doubt, be presently objected, Is not
this an universal proposition, ALL GOLD IS MALLEABLE? To which I answer,
It is a very complex idea the word gold stands for. But then here is
nothing affirmed of gold, but that that sound stands for an idea in
which malleableness is contained: and such a sort of truth and certainty
as this it is, to say a centaur is four-footed. But if malleableness make
not a part of the specific essence the name of gold stands for, it is
plain, ALL GOLD IS MALLEABLE, is not a certain proposition. Because,
let the complex idea of gold be made up of whichsoever of its other
qualities you please, malleableness will not appear to depend on that
complex idea, nor follow from any simple one contained in it: the
connexion that malleableness has (if it has any) with those other
qualities being only by the intervention of the real constitution of its
insensible parts; which, since we know not, it is impossible we should
perceive that connexion, unless we could discover that which ties them
together.
10. As far as any such Co-existence can be known, so far Universal
Propositions maybe certain. But this will go but a little way.
The more, indeed, of these co-existing qualities we unite into one
complex idea, under one name, the more precise and determinate we make
the signification of that word; but never yet make it thereby more
capable of universal certainty, IN RESPECT OF OTHER QUALITIES NOT
CONTAINED IN OUR COMPLEX IDEA: since we perceive not their connexion or
dependence on one another; being ignorant both of that real constitution
in which they are all founded, and also how they flow from it. For the
chief part of our knowledge concerning substances is not, as in other
things, barely of the relation of two ideas that may exist separately;
but is of the necessary connexion and co-existence of several distinct
ideas in the same subject, or of their repugnancy so to co-exist. Could
we begin at the other end, and discover what it was wherein that colour
consisted, what made a body lighter or heavier, what texture of parts
made it malleable, fusible, and fixed, and fit to be dissolved in this
sort of liquor, and not in another;--if, I say, we had such an idea
as this of bodies, and could perceive wherein all sensible qualities
originally consist, and how they are produced; we might frame such
abstract ideas of them as would furnish us with matter of more general
knowledge, and enable us to make universal propositions, that should
carry general truth and certainty with them. But whilst our complex
ideas of the sorts of substances are so remote from that internal real
constitution on which their sensible qualities depend, and are made up
of nothing but an imperfect collection of those apparent qualities our
senses can discover, there can be few general propositions concerning
substances of whose real truth we can be certainly assured; since there
are but few simple ideas of whose connexion and necessary co-existence
we can have certain and undoubted knowledge. I imagine, amongst all the
secondary qualities of substances, and the powers relating to them,
there cannot any two be named, whose necessary co-existence, or
repugnance to co-exist, can certainly be known; unless in those of the
same sense, which necessarily exclude one another, as I have elsewhere
showed. No one, I think, by the colour that is in any body, can
certainly know what smell, taste, sound, or tangible qualities it has,
nor what alterations it is capable to make or receive on or from other
bodies. The same may be said of the sound or taste, &c. Our specific
names of substances standing for any collections of such ideas, it
is not to be wondered that we can with them make very few general
propositions of undoubted real certainty. But yet so far as any complex
idea of any sort of substances contains in it any simple idea, whose
NECESSARY co-existence with any other MAY be discovered, so far
universal propositions may with certainty be made concerning it: v.g.
could any one discover a necessary connexion between malleableness and
the colour or weight of gold, or any other part of the complex idea
signified by that name, he might make a certain universal proposition
concerning gold in this respect; and the real truth of this proposition,
that ALL GOLD IS MALLIABLE, would be as certain as of this, THE THREE
ANGLES OF ALL RIGHT-LINED TRIANGLES ARE ALL EQUAL TO TWO RIGHT ONES.
11. The Qualities which make our complex Ideas of Substances depend
mostly on external, remote, and unperceived Causes.
Had we such ideas of substances as to know what real constitutions
produce those sensible qualities we find in them, and how those
qualities flowed from thence, we could, by the specific ideas of
their real essences in our own minds, more certainly find out their
properties, and discover what qualities they had or had not, than we can
now by our senses: and to know the properties of gold, it would be
no more necessary that gold should exist, and that we should make
experiments upon it, than it is necessary for the knowing the properties
of a triangle, that a triangle should exist in any matter, the idea in
our minds would serve for the one as well as the other. But we are so
far from being admitted into the secrets of nature, that we scarce so
much as ever approach the first entrance towards them. For we are wont
to consider the substances we meet with, each of them, as an entire
thing by itself, having all its qualities in itself, and independent of
other things; overlooking, for the most part, the operations of those
invisible fluids they are encompassed with, and upon whose motions and
operations depend the greatest part of those qualities which are taken
notice of in them, and are made by us the inherent marks of distinction
whereby we know and denominate them. Put a piece of gold anywhere by
itself, separate from the reach and influence of all other bodies,
it will immediately lose all its colour and weight, and perhaps
malleableness too; which, for aught I know, would be changed into a
perfect friability. Water, in which to us fluidity is an essential
quality, left to itself, would cease to be fluid. But if inanimate
bodies owe so much of their present state to other bodies without them,
that they would not be what they appear to us were those bodies that
environ them removed; it is yet more so in vegetables, which are
nourished, grow, and produce leaves, flowers, and seeds, in a constant
succession. And if we look a little nearer into the state of animals,
we shall find that their dependence, as to life, motion, and the
most considerable qualities to be observed in them, is so wholly on
extrinsical causes and qualities of other bodies that make no part of
them, that they cannot subsist a moment without them: though yet those
bodies on which they depend are little taken notice of, and make no part
of the complex ideas we frame of those animals. Take the air but for a
minute from the greatest part of living creatures, and they presently
lose sense, life, and motion. This the necessity of breathing has forced
into our knowledge. But how many other extrinsical and possibly very
remote bodies do the springs of these admirable machines depend on,
which are not vulgarly observed, or so much as thought on; and how many
are there which the severest inquiry can never discover? The inhabitants
of this spot of the universe, though removed so many millions of
miles from the sun, yet depend so much on the duly tempered motion of
particles coming from or agitated by it, that were this earth removed
but a small part of the distance out of its present situation, and
placed a little further or nearer that source of heat, it is more than
probable that the greatest part of the animals in it would immediately
perish: since we find them so often destroyed by an excess or defect of
the sun's warmth, which an accidental position in some parts of this our
little globe exposes them to. The qualities observed in a loadstone must
needs have their source far beyond the confines of that body; and the
ravage made often on several sorts of animals by invisible causes, the
certain death (as we are told) of some of them, by barely passing
the line, or, as it is certain of other, by being removed into a
neighbouring country; evidently show that the concurrence and operations
of several bodies, with which they are seldom thought to have anything
to do, is absolutely necessary to make them be what they appear to us,
and to preserve those qualities by which we know and distinguish them.
We are then quite out of the way, when we think that things contain
WITHIN THEMSELVES the qualities that appear to us in them; and we
in vain search for that constitution within the body of a fly or an
elephant, upon which depend those qualities and powers we observe in
them. For which, perhaps, to understand them aright, we ought to look
not only beyond this our earth and atmosphere, but even beyond the sun
or remotest star our eyes have yet discovered. For how much the being
and operation of particular substances in this our globe depends on
causes utterly beyond our view, is impossible for us to determine. We
see and perceive some of the motions and grosser operations of things
here about us; but whence the streams come that keep all these curious
machines in motion and repair, how conveyed and modified, is beyond our
notice and apprehension: and the great parts and wheels, as I may so
say, of this stupendous structure of the universe, may, for aught we
know, have such a connexion and dependence in their influences and
operations one upon another, that perhaps things in this our mansion
would put on quite another face, and cease to be what they are, if some
one of the stars or great bodies incomprehensibly remote from us,
should cease to be or move as it does. This is certain: things, however
absolute and entire they seem in themselves, are but retainers to other
parts of nature, for that which they are most taken notice of by us.
Their observable qualities, actions, and powers are owing to something
without them; and there is not so complete and perfect a part that we
know of nature, which does not owe the being it has, and the excellences
of it, to its neighbours; and we must not confine our thoughts within
the surface of any body, but look a great deal further, to comprehend
perfectly those qualities that are in it.
12. Our nominal essences of Substances furnish few universal
propositions about them that are certain.
If this be so, it is not to be wondered that we have very imperfect
ideas of substances, and that the real essences, on which depend their
properties and operations, are unknown to us. We cannot discover so much
as that size, figure, and texture of their minute and active parts,
which is really in much less the different motions and impulses made in
and upon them by bodies from without, upon which depends, and by which
is formed the greatest and most remarkable part of those qualities we
observe in them, and of which our complex ideas of them are made up.
This consideration alone is enough to put an end to all our hopes of
ever having the ideas of their real essences; which whilst we want, the
nominal essences we make use of instead of them will be able to
furnish us but very sparingly with any general knowledge, or universal
propositions capable of real certainty.
13. Judgment of Probability concerning Substances may reach further: but
that is not Knowledge.
We are not therefore to wonder, if certainty be to be found in very few
general propositions made concerning substances: our knowledge of their
qualities and properties goes very seldom further than our senses reach
and inform us. Possibly inquisitive and observing men may, by strength
of judgment, penetrate further, and, on probabilities taken from wary
observation, and hints well laid together, often guess right at what
experience has not yet discovered to them. But this is but guessing
still; it amounts only to opinion, and has not that certainty which is
requisite to knowledge. For all general knowledge lies only in our own
thoughts, and consists barely in the contemplation of our own abstract
ideas. Wherever we perceive any agreement or disagreement amongst them,
there we have general knowledge; and by putting the names of those ideas
together accordingly in propositions, can with certainty pronounce
general truths. But because the abstract ideas of substances, for
which their specific names stand, whenever they have any distinct
and determinate signification, have a discoverable connexion or
inconsistency with but a very few other ideas, the certainty of
universal propositions concerning substances is very narrow and scanty,
in that part which is our principal inquiry concerning them; and there
are scarce any of the names of substances, let the idea it is applied
to be what it will, of which we can generally, and with certainty,
pronounce, that it has or has not this or that other quality belonging
to it, and constantly co-existing or inconsistent with that idea,
wherever it is to be found.
14. What is requisite for our Knowledge of Substances.
Before we can have any tolerable knowledge of this kind, we must First
know what changes the primary qualities of one body do regularly produce
in the primary qualities of another, and how. Secondly, We must know
what primary qualities of any body produce certain sensations or ideas
in us. This is in truth no less than to know ALL the effects of matter,
under its divers modifications of bulk, figure, cohesion of parts,
motion and rest. Which, I think every body will allow, is utterly
impossible to be known by us without revelation. Nor if it were revealed
to us what sort of figure, bulk, and motion of corpuscles would produce
in us the sensation of a yellow colour, and what sort of figure, bulk,
and texture of parts in the superficies of any body were fit to give
such corpuscles their due motion to produce that colour; would that be
enough to make universal propositions with certainty, concerning the
several sorts of them; unless we had faculties acute enough to perceive
the precise bulk, figure, texture, and motion of bodies, in those minute
parts, by which they operate on our senses, so that we might by those
frame our abstract ideas of them. I have mentioned here only
corporeal substances, whose operations seem to lie more level to our
understandings. For as to the operations of spirits, both their thinking
and moving of bodies, we at first sight find ourselves at a loss; though
perhaps, when we have applied our thoughts a little nearer to the
consideration of bodies and their operations, and examined how far our
notions, even in these, reach with any clearness beyond sensible matter
of fact, we shall be bound to confess that, even in these too, our
discoveries amount to very little beyond perfect ignorance and
incapacity.
15. Whilst our complex Ideas of Substances contain not ideas of their
real Constitutions, we can make but few general Propositions concerning
them.
This is evident, the abstract complex ideas of substances, for which
their general names stand, not comprehending their real constitutions,
can afford us very little universal certainty. Because our ideas of them
are not made up of that on which those qualities we observe in them, and
would inform ourselves about, do depend, or with which they have any
certain connexion: v.g. let the ideas to which we give the name MAN be,
as it commonly is, a body of the ordinary shape, with sense, voluntary
motion, and reason joined to it. This being the abstract idea, and
consequently the essence of OUR species, man, we can make but very few
general certain propositions concerning man, standing for such an idea.
Because, not knowing the real constitution on which sensation, power of
motion, and reasoning, with that peculiar shape, depend, and whereby
they are united together in the same subject, there are very few other
qualities with which we can perceive them to have a necessary connexion:
and therefore we cannot with certainty affirm: That all men sleep by
intervals; That no man can be nourished by wood or stones; That all men
will be poisoned by hemlock: because these ideas have no connexion nor
repugnancy with this our nominal essence of man, with this abstract idea
that name stands for. We must, in these and the like, appeal to trial in
particular subjects, which can reach but a little way. We must content
ourselves with probability in the rest: but can have no general
certainty, whilst our specific idea of man contains not that real
constitution which is the root wherein all his inseparable qualities are
united, and from whence they flow. Whilst our idea the word MAN stands
for is only an imperfect collection of some sensible qualities and
powers in him, there is no discernible connexion or repugnance between
our specific idea, and the operation of either the parts of hemlock or
stones upon his constitution. There are animals that safely eat hemlock,
and others that are nourished by wood and stones: but as long as we want
ideas of those real constitutions of different sorts of animals whereon
these and the like qualities and powers depend, we must not hope to
reach certainty in universal propositions concerning them. Those few
ideas only which have a discernible connexion with our nominal essence,
or any part of it, can afford us such propositions. But these are so
few, and of so little moment, that we may justly look on our certain
general knowledge of substances as almost none at all.
16. Wherein lies the general Certainty of Propositions.
To conclude: general propositions, of what kind soever, are then only
capable of certainty, when the terms used in them stand for such ideas,
whose agreement or disagreement, as there expressed, is capable to be
discovered by us. And we are then certain of their truth or falsehood,
when we perceive the ideas the terms stand for to agree or not agree,
according as they are affirmed or denied one of another. Whence we may
take notice, that general certainty is never to be found but in
our ideas. Whenever we go to seek it elsewhere, in experiment or
observations without us, our knowledge goes not beyond particulars. It
is the contemplation of our own abstract ideas that alone is able to
afford us general knowledge.