MATERIAL PHENOMENA AND THEIR REALITY.
We have seen the necessity and nature of matter as deductions from
the fundamental principles of Leibniz. We have seen that matter is
a phenomenon or manifestation of spirit in an imperfect and confused
way. But why should it appear as moving, as extended, as resisting,
as having cohesion, with all the concrete qualities which always mark
it? Is there any connection between these particular properties of
matter as physical, and its "metaphysical" or ideal character? These
are the questions which now occupy us. Stated more definitely, they
take the following form: Is there any essential connection between the
properties of matter as a metaphysical element, and its properties as a
sensible fact of experience? Leibniz holds that there is. He does not,
indeed, explicitly take the ground that we can deduce _a priori_ all
the characteristics of matter as a fact of actual experience from its
rational notion, but he thinks we can find a certain analogy between
the two, that the sensible qualities are images or reflexes of the
spiritual qualities, witnessing, so far as possible, to their origin in
pure energy.
His position is as follows: that which in the monad is activity or
substantial, is, in sensible matter, motion. That which in the monad
is lack of a given activity, that which constitutes its subordinate
position in the hierarchy of monads, is, in the sphere of material
things, inertia. That which in the spiritual world is the individuality
of monads, making each forever ideally distinct from every other, is,
in the phenomenal realm, resistance or impenetrability. The perfect
continuity of monads in the _mundus intelligibilis_ has also its
counterpart in the _mundus sensibilis_ in the diffusion or extension of
physical things.
Instead of following out this analogy directly, it will rather be
found convenient to take up Leibniz's thought in its historical
connection. We have already alluded to the fact that he began as
a Cartesian, and that one of the first ideas which repelled him
from that system of thought was the notion that the essence of
matter is extension. His earliest philosophical writings, as he was
gradually coming to the thoughts which thereafter dominated him,
are upon this point. In general, his conclusions are as follows:
If matter were extension, it would be incapable of passion or of
action. Solidity, too, is a notion entirely opposed to the conception
of mere extension. The idea of matter as extension contradicts some
of the known laws of motion. It requires that the quantity of motion
remain unchanged whenever two bodies come in contact, while as matter
of fact it is the quantity of energy, that which the motion is capable
of effecting, that remains unchanged; or, as he more often puts the
objection, the Cartesian notion of matter requires that matter be
wholly indifferent to motion, that there be nothing in it which resists
motion when imparted. But, says Leibniz, there is something resisting,
that to which Keppler gave the name "inertia." It is not found to be
true if one body impacts upon another that the second moves without
diminishing the velocity or changing the direction of the first. On
the other hand, just in proportion to the size of the second body,
it resists and changes the motion of the first, up to the point of
causing the first to rebound if small in comparison. And when it was
replied that the retardation was due to the fact that the force moving
the first body had now to be divided between two, Leibniz answered
that this was simply to give up the contention, and besides the notion
of extension to use that of force. If extension were the essence of
matter, it should be possible to deduce all the properties of matter,
or at least to account for them all, from it. But since, as just seen,
this does not enable us to account for any of them, since for any of
its concrete qualities we have to fall back on force, it is evident
where the true essence of matter is to be found.
Leibniz has another argument of a logical nature, as those already
referred to are of a physical: "Those who claim that extension is a
substance, reverse the order of words as well as of thoughts. Besides
extension there must be a subject which is extended; that is to
say, something to which it belongs to be repeated or continued. For
extension is nothing but a repetition or continued multiplication
of that which is spread out,--it is a plurality, a continuity, a
co-existence of parts. Consequently, extension does not suffice to
explain the nature of the repeated or manifold substance, of which the
notion is anterior to that of its repetition." Extension, in other
words, is nothing substantial, it is not something which can exist
by itself; it is only a quality, a property, a mode of being. It is
always relative to something which has extension. As Leibniz says
elsewhere: "I insist that extension is only an _abstraction_, and
requires something which is extended. It presupposes some quality,
some attribute, some nature in a subject which is extended, diffused,
or continued. Extension is a diffusion of this quality. For example,
in milk there is an extension or diffusion of whiteness; in the diamond
an extension or diffusion of hardness; in body in general a diffusion
of antitypia or materiality. There is accordingly in body something
anterior to extension."
From the physical side, therefore, we find it impossible to account
for the concrete properties of material phenomena from extension; on
the logical we find that the idea of extension is always relative to
that which is extended. What is that which is to be considered as the
bearer of extension and the source of physical qualities? We are led
back to the point at which we left the matter in the last chapter. It
is force, and force both passive and active. Leibniz uses the term
"matter" in at least three senses: it is the metaphysical element of
passive force _in_ the monad; it is the monad itself considered as,
upon the whole, externally conditioned or unconscious; and it is the
phenomenon resulting from the aggregation of the monads in the second
sense. The first is naked matter, and is a pure abstraction; the second
is the monad as material, as opposed to the monad, as soul; the third
is clothed, or second matter, or, concretely, body, _corpus_. The first
is unreal by itself; the second is one phase of substance; the third
is not substantial, but is a reality, though a phenomenal one. It
is from the substantial monad that we are to explain the two things
now demanding explanation,--that element in _bodies_ (matter in third
sense) which is the source of their physical properties, and that which
is the subject, the carrier, so to speak, of extension.
That of which we are in search as the source of the physical qualities
of bodies is motion. This is not force, but its "image." It is force,
says Leibniz, that "is the real element in motion; that is to say,
it is that element which out of the present state induces a change in
the future state." As force, in other words, is the causal activity
which effects the development of one "representation" of a monad out
of another, so motion, in the realm of phenomena, is not only change,
but change which is continuous and progressive, each new position
being dependent upon the foregoing, and following out of it absolutely
without break.
Motion, therefore, is the manifestation of the ideal unity of
substance,--a unity not of mere static inherence, but of a continuous
process of activity. It is from this standpoint that Leibniz accounts
for the so-called transference of motion from one body to another upon
contact. The ordinary view of this, which looks at it as if one body
loses the motion which another body gains, Leibniz ridicules, saying
that those who hold this view seem to think that motion is a kind of
thing, resembling, perchance, salt dissolved in water. The right view,
on the other hand, does away with all appearance of mystery in the
carrying over of motion from one body to another, for it recognizes
that continuity is the very essence of motion, and that we do not have
two things and a third process, but that the two bodies are phases or
elements in one and the same system of movement.
Starting from this idea of motion, then, Leibniz is to account for
the actual qualities of matter as found in experience. These are
the form, magnitude, cohesion, resistance, and the purely sensible
qualities of objects. "First" matter, that is, abstract matter,
may be conceived, according to Leibniz, as perfectly homogeneous, a
"subtle fluid," in his words, without any distinction of parts or of
solidity. But this _is_ an abstract notion. It is what matter would
be without motion. Motion necessarily differentiates this plenum
of homogeneity, and thus causes distinctions of figure (that is,
boundaries of parts) and varieties of cohesion, or the varying solidity
and fluidity of bodies. The latter difference is indeed the ultimate
one. The principle of continuity or gradation, as applied to motion,
makes it necessary that motions should not be in any two places of
exactly the same energy. The result is that the original fluid matter
is everywhere differently divided. Motion, entering into the uniform
plenum, introduces distinction; it causes so much of the matter as is
affected by a given movement to collect together and form in appearance
a coherent body, as opposed to surrounding bodies which are affected
by different degrees of energy. But even this is only approximate;
the same principle of continuity must be applied within any apparently
coherent body; its parts, while, in relation to other bodies, they have
the same amount of motion, are in relation to one another differently
affected. There are no two having exactly the same motion; if they had,
there would be no distinction between them; and thus, according to the
principle of Leibniz, they would be the same.
It follows at once from this that there is in the universe no body of
absolute hardness or solidity, nor of entire softness or fluidity. A
perfectly solid body would be one whose system of motions could not be
affected by any other system,--a body which by motion had separated
itself from motion, or become absolute. This is evidently an idea
which contradicts itself, for the very essence of motion is continuity
or relation. A body perfectly fluid, on the other hand, would be one
in which there was no resistance offered to other motions,--a body,
in other words, in which there are no movements that, entering into
connection with one another, form a relative opposition to other
movements. It would be a body isolated or out of relation with the
general system of motions, and hence an impossibility. There is no last
term either of solidity or of fluidity.
It equally follows as matter of course that there is no indivisible
particle of matter,--no atom. The infinity of degrees of motion
implies a corresponding division of matter. As already said, it is
only in contrast with other relatively constant systems of motion
that any body is of uniform motion; in reality there is everywhere
throughout it variety of movement, and hence complete divisibility, or
rather, complete division. If Leibniz were to employ the term "atom"
at all, it could be only in the sense of the modern dynamical theory
(of which, indeed, he is one of the originators), according to which
the atom is not defined by its spatial position and outlines, but,
by the range of its effects, as the centre of energies of infinite
circumference. Correlative to the non-existence of the atom is the
non-existence of the vacuum. The two imply each other. The hard,
limited, isolated body, having no intrinsic relations with other
bodies, must have room to come into external relations with them. This
empty space, which is the theatre of such accidental contacts as may
happen, is the vacuum. But if bodies are originally in connection
with one another, if they are in reality but differentiations of
varying degrees of motion within one system of motion, then there
is no necessity for the vacuum,--nay, there is no place for it. The
vacuum in this case could mean only a break, a chasm, in the order
of nature. According to the theory of Leibniz, "bodies" are but the
dynamic divisions of the one energy that fills the universe; their
separateness is not an independent possession of any one of them
or of all together, but is the result of relations to the entire
system. Their apparent isolation is only by reason of their actual
connections. To admit a vacuum anywhere, would thus be to deny the
relatedness of the parts separated by it. The theory of the atom and
the vacuum are the two phases of the metaphysical assumption of an
indefinite plurality of independent separate realities. The theory
of Leibniz, resting as it does on the idea of a perfect unity of
interrelated members, must deny both of these aspects. Were we making
an extended analysis of the opposed view, it would be necessary to
point out that it denies itself. For it is only _through_ the vacuum
that the atoms are isolated or independent, and the sole function of
the vacuum is to serve as the background of the atoms. The atoms are
separated only in virtue of their connection, and the vacuum is what it
is--pure emptiness--only on account of that which is in it. In short,
the theory is only an abstract and incomplete way of grasping the
thought of relation or mediated unity.
We have thus discovered that all motions conspire together, or
form a system. But in their unity they do not cease to be motions,
or variously differentiated members. Through this differentiation,
or mutual reaction of motions, there comes about the appearance of
boundaries, of separation. From these boundaries or terminations
arise the form and size of bodies. From motion also proceeds the
cohesion of bodies, in the sense that each relative system resists
dissolution, or hangs together. Says Leibniz, "The motions, since they
are conspiring, would be troubled by separation; and accordingly this
can be accomplished only by violence and with resistance." Not only
form, size, and stability depend upon motion, but also the sensible,
the "secondary" qualities. "It must not be supposed that color, pain,
sound, etc., are arbitrary and without relation to their causes. It is
not God's way to act with so little reason and order. There is a kind
of resemblance, not entire, but of relation, of order. We say, for
example, 'Light is in the fire,' since there are motions in the fire
which are imperceptible in their separation, but which are sensible
in their conjunction or confusion; and this is what is made known in
the idea of light." In other words, color, sound, etc., even pain,
are still the perception of motion, but in a confused way. We thus see
how thoroughly Leibniz carries back all the properties of bodies to
motion. To sum up, motion is the origin of the relative solidity, the
divisibleness, the form, the size, the cohesion, or active resistance
of bodies, and of their properties as made known to us in immediate
sensation.
In all that has been said it has been implied that extension is already
in existence; "first matter" is supposed to fill all space, and motion
to determine it to take upon itself its actual concrete properties. But
this "first matter," when thus spoken of, has a somewhat mythological
sound, even if it be admitted that it is an abstraction. For how can
an abstraction be extended in space, and how can it form, as it were,
a background upon which motion displays itself? The idea of "first
matter" in its relation to extension evidently demands explanation. In
seeking this explanation we shall also learn about that "subject" which
Leibniz said was necessarily presupposed in extension, as a concrete
thing is required for a quality.
The clew to the view of Leibniz upon this point may be derived, I
think, from the following quotations:--
"If it were possible to see what makes extension, that kind of
extension which falls under our eyes at present would vanish, and
our minds would perceive nothing else than simple realities existing
in mutual externality to one another. It would be as if we could
distinguish the minute particles of matter variously disposed from
which a painted image is formed: if we could do it, the image, which is
nothing but a phenomenon, would vanish. . . . If we think of two
simple realities as both existing at the same time, but distinct from
one another, we look at them as if they were outside of one another,
and hence conceive them as extended."
The monads are outside of one another, not spatially, but ideally;
but this reciprocal distinction from one another, if it is to appear
in phenomenal mode, must take the form of an image, and the image is
spatial. But if the monads were pure activity, they would _not_ take
phenomenal form or appear in an image. They would always be thought
just as they are,--unextended activities realizing the spiritual
essence of the universe. But they are not pure activity; they are
passive as well. It is in virtue of this passive element that the ideal
externality takes upon itself phenomenal or sensible form, and thus
appears as spatial externality.
Leibniz, in a passage already quoted, refers to the diffusion
of materiality or _antitypia_. This word, which is of frequent
occurrence in the discussions of Leibniz, he translates generally as
"impenetrability," sometimes as "passive resistance." It corresponds to
the solidity or resistance of which Locke spoke as forming the essence
of matter. Antitypia is the representation by a monad of the passive
element in other monads. Leibniz sometimes speaks as if all created
monads had in themselves antitypia, and hence extension; but he more
accurately expresses it by saying that they need (_exigent_) it. This
is a technical term which he elsewhere uses to express the relation of
the possible to the actual. The possible "needs" the actual, not in
the sense that it _necessarily_ requires existence, but in the sense
that when the actual gives it existence, it is the logical basis of the
actual,--the actual, on the other hand, being its real complement. The
passivity of the monad is therefore at once the logical basis and
the possibility of the impenetrability of matter. It is owing to the
passivity of the monad that it does not adequately reflect (that it is
not transparent to, so to speak) the activities of other monads. In
its irresponsiveness, it fails to mirror them in itself. It may be
said, therefore, to be impenetrable to them. They in turn, so far as
they are passive, are impenetrable to it. Now the impenetrable is,
_ex vi terminis_, that which excludes, and that which excludes, not in
virtue of its active elasticity, but in virtue of its mere inertia,
its dead weight, as it were, of resistance. But mutual exclusion of
this passive sort constitutes that which is extended. Extension is
the abstract quality of this concrete subject. Such, in effect, is the
deduction which Leibniz gives of body, or physical matter, from matter
as metaphysical; of matter as sensible or phenomenal, from matter as
ideal or as intelligible.
If we put together what has been said, it is clear that material
phenomena (bodies, _corpora_, in Leibniz's phrase) simply repeat
in another sphere the properties of the spiritual monad. There
is a complete parallelism between every property, each to each,
and this necessarily; for every property of "body" is in logical
dependence upon, and a phenomenalization of, some spiritual or ideal
quality. Motion is the source of all the dynamic qualities of body, and
motion is the reflection of Force, that force which is Life. But this
force in all finite forms is conditioned by a passive, unreceptive,
unresponsive factor; and this must also have its correlate in
"body." This correlate is primarily impenetrability, and secondarily
extension. Thus it is that concrete body always manifests motion,
indeed, but upon a background of extension, and against inertia. It
never has free play; had it an unrestrained field of activity,
extension would disappear, and spatial motion would vanish into
ideal energy. On the other hand, were the essence of matter found in
resistance or impenetrability, it would be wholly inert; it would be a
monotone of extension, without variety of form or cohesion. As Leibniz
puts it with reference to Locke, "body" implies motion, or impetuosity,
resistance, and cohesion. Motion is the active principle, resistance
the passive; while cohesion, with its various grades of completeness,
which produce form, size, and solidity, is the result of their union.
Leibniz, like Plato, has an intermediary between the rational and
the sensible; and as Plato found that it was mathematical relations
that mediate between the permanent and unified Ideas and the changing
manifold objects, so Leibniz found that the relations of space and time
form the natural transition from the sphere of monads to the world
of bodies. As Plato found that it was the possibility of applying
mathematical considerations to the world of images that showed the
participation of Ideas in them, and constituted such reality as they
had, so Leibniz found that space and time formed the element of
order and regularity among sense phenomena, and thus brought them
into kinship with the monads and made them subjects of science. It
is implied in what is here said that Leibniz distinguished between
space and time on the one hand, and duration and extension on the
other. This distinction, which Leibniz draws repeatedly and with great
care, has been generally overlooked by his commentators. But it is
evident that this leaves Leibniz in a bad plight. Mathematics, in its
various forms, is the science of spatial and temporal relations. But if
these are identical with the forms of duration and extension, they are
purely phenomenal and sensible. The science of them, according to the
Leibnizian distinction between the absolutely real and the phenomenally
real, would be then a science of the confused, the imperfect,
and the transitory; in fact, no science at all. But mathematics,
on the contrary, is to Leibniz the type of demonstrative, conclusive
science. Space and time are, in his own words, "innate ideas," and
the entire science of them is the drawing out of the content of these
innate--that is, rational, distinct, and eternal--ideas. But extension
and duration are sensible experiences; not rational, but phenomenal;
not distinct, but confused; not eternal, but evanescent. We may be sure
that this contradiction would not escape Leibniz, although it has many
of his critics and historians.
It is true, however, that he occasionally uses the terms as synonymous;
but this where the distinction between them has no bearing on the
argument in hand, and where the context determines in what sense
the term is used. The distinction which he actually makes, and to
which he keeps when space and time are the subject of discussion,
is that extension and duration are qualities or predicates of
objects and events, while space and time are relations, or orders of
existence. Extension and duration are, as he says, the _immensity_, the
mass, the continuation, the repetition, of some underlying subject. But
space and time are the _measure_ of the mass, the rule or law of the
continuation, the order or mode of the repetition. Thus immediately
after the passage already quoted, in which he says that extension
in body is the diffusion of materiality, just as whiteness is the
diffusion of a property of milk, he goes on to say "that extension is
to space as duration to time. Duration and extension are attributes of
things; but space and time are to be considered, as it were, outside
of things, and as serving to measure them." Still more definitely
he says: "Many confound the immensity or extent of things with the
space by means of which this extent is defined. Space is not the
extension of body, any more than duration is its time. Things keep
their extension, not always their space. Everything has its own extent
and duration; but it does not have a time of its own, nor keep for its
own a space." Or, as he expresses the latter idea elsewhere, space is
like number, in the sense that it is indifferent to spatial things,
just as number is indifferent to _res numerata_. Just as the number
five is not a quality or possession of any object, or group of objects,
but expresses an order or relation among them, so a given space is not
the property of a thing, but expresses the order of its parts to one
another. But extension, on the other hand, is a property of the given
objects. While extension, therefore, must always belong to some actual
thing, space, as a relation, is as applicable to possible things as to
actual existences; so that Leibniz sometimes says that time and space
"express possibilities." They are that which makes it possible for a
definite and coherent order of experiences to exist. They determine
existence in some of its relations, and as such are logically
prior to any given forms of existence; while extent and duration are
always qualities of some given form of existence, and hence logically
derivative. Since time and space "characterize possibilities" as well
as actualities, it follows as a matter of course "that they are of the
nature of eternal truths, which relate equally to the possible and to
the existing." Being an eternal truth, space must have its place in
that which is simply the active unity of all eternal truths,--the mind
of God. "Its truth and reality are based upon God. It is an order whose
source is God." Since God is _purus actus_, he is the immediate, the
efficient source only of that which partakes in some degree of his own
nature, or is rational; and here is another clear point of distinction
between space and extension, between time and duration.
But we must ask more in detail regarding their nature. Admitting
that they are relations, ideal and prior to particular experiences,
the question must be asked, What sort of relations are they; how are
they connected with the purely spiritual on one hand, and with the
phenomenal on the other? Leibniz's most extended answers to these
questions are given in his controversy with Clarke. The latter took
much the same position regarding the nature of space (though not,
indeed, concerning the origin of its idea) as Locke, and the arguments
which Leibniz uses against him he might also have used, for the most
part, against Locke. Locke and Clarke both conceived of space and
time as wholly without intrinsic relation to objects and events. It
is especially against this position that Leibniz argues, holding that
space and time are simply orders or relations of objects and events,
that space exists only where objects are existing, and that it is
the order of their co-existence, or of their possible co-existence;
while time exists only as events are occurring, and is the relation of
their succession. Clarke, on the other hand, speaks of the universe of
objects as bounded by and moving about in an empty space, and says that
time existed before God created the finite world, so that the world
came into a time already there to receive its on-goings, just as it
fell into a space already there to receive its co-existences.
To get at the ideas of Leibniz, therefore, we cannot do better than
follow the course of this discussion. He begins by saying that
both space and time are purely relative, one being the order of
co-existences, the other of successions. Space characterizes in terms
of possibility an order of things existing at the same time, so far as
they exist in mutual relations (_ensemble_), without regard to their
special modes of existence. As to the alternate doctrine that space
is a substance, or something absolute, it contradicts the principle
of sufficient reason. Were space something absolutely uniform, without
things placed in it, there would be no difference between one part and
another, and it would be a matter of utter indifference to God why he
gave bodies certain positions in space rather than others; similarly
it would be a matter of indifference why he created the world when
he did, if time were something independent of events. In other words,
the supposed absoluteness of space and time would render the action of
God wholly without reason, capricious, and at haphazard. Similarly, it
contradicts the principle of "indiscernibles," by which Leibniz means
the principle of specification, or distinction. According to him,
to suppose two things exactly alike, is simply to imagine the same
thing twice. Absolute uniformity, wholly undifferentiated, is a fiction
impossible to realize in thought. "Space considered without objects has
nothing in it to determine it; it is accordingly nothing actual. The
parts of space must be determined and distinguished by the objects
which are in them." Finally, were space and time absolutely real things
in themselves, they would be independent of God, and even limitations
upon him. "They would be more substantial than substances. God would
not be able to change or destroy them. They would be immutable and
eternal in every part. Thus there would be an infinity of eternal
things (these parts) independent of God." They would limit God because
he would be obliged to exist _in_ them. Only by existing through this
independent time would he be eternal; only by extending through this
independent space would he be omnipresent. Space and time thus become
gods themselves.
When Clarke declares that by the absoluteness of space and time he does
not mean that they are themselves substances, but only properties,
attributes of substance, Leibniz advances the same arguments in
different form. If space were the property of the things that are
in space, it would belong now to one substance, now to another, and
when empty of all material substance, even to an immaterial substance,
perhaps to God. "Truly a strange attribute which is handed about from
one thing to another. Substances thus leave their accidents as if they
were old clothes, and other substances put them on." Since these finite
spaces are in infinite space, and the latter is an attribute of God,
it must be that an attribute of God is composed of parts, some of them
empty, some full, some round, some square. So, too, whatever is in time
would help make one of the attributes of God. "Truly a strange God,"
says Leibniz, "this Deity of parts" (_ce Dieu à parties_). Clarke's
reply to this was that space and time are attributes of God and of
God alone, not of things in space and time,--that, indeed, strictly
speaking, there are no parts in space or in time; they are absolutely
one. This was virtually to give up the whole matter. It was to deny
the existence of finite spaces and times, and to resolve them into
an indefinite attribute of God. Such a view, as Leibniz points out,
not only is contrary to experience, but affords no aid in determining
the actual concrete forms and situations of bodies, and durations
and successions of events. The absolute space and time, having no
parts, are wholly out of relations to these concrete existences. The
latter require, therefore, a space and a time that are relations or
orders. Clarke's hypothesis is, as Leibniz says, wholly without use
or function, and requires a theory like that of Leibniz to account
for the actually determinate forms of experience. In his last reply
Clarke shifts his ground again, and says that space and time are
_effects_ of God's existence; "they are the necessary results of his
existence." "His existence is the cause of space and time." The death
of Leibniz prevented any further reply. It is not hard to imagine,
however, that in a general way his reply would have been to ask how
space and time are at once attributes essential and necessary to God,
as constituting his immensity and eternity, and effects dependent upon
his existence. To take this latter position, indeed, seems to abandon
the position that they are absolute, and to admit that, like the rest
of God's creation, they are relative and finite.
So much for Leibniz's polemic. Its meaning is that space and time have
significance only with reference to things and events, that they are
the intellectual, the ideal side of these objects and occurrences,
being the relations which give them order and unity. A space which
is not the space of objects, which is not space in and through
objects, is an inanity; it is not spirit, it is not matter; it is
not a relation of either. It is nothingness magnified to infinity,
and then erected into existence. And all for nothing; for it does not
enable us to account for a single concrete fact of experience. For
this we must have recourse to relations and orders of existence. Space
is therefore to be defined as the order which makes it possible for
objects to have situation; time as that which makes it possible for
events to have dating,--not as if they were actually prior to them,
and although nothings in themselves, yet capable of giving concrete
determination to things, but as _actually_ the relations themselves,
and as _ideally_ necessary for the coherent experience of co-existent
objects and of connected events. As Leibniz puts it epigrammatically:
"Space is the order of possible constants; time the order of inconstant
possibilities."
We have finished the exposition of the views of Leibniz about matter
and material facts. One question, however, remains to be discussed,--a
question which Leibniz's contemporary critics would not allow him to
pass over in silence, even had he been so disposed. What is the reality
of matter, of motion, of space, and of time? Since they are, as Leibniz
says, only phenomena, not absolute realities, what distinguishes them
from dreams, from illusions? What distinguishes sensible phenomena from
capricious fantasies, and gives them reality?
Leibniz begins his answer by pointing out that the mere fact that
bodies are phenomena does not make them unreal. To say that anything
is phenomenal is to say that it is sensible; but "the senses make
no declaration regarding metaphysical matters" such as truth and
reality. The senses, in a word, only inform us that the experiences
are there for the senses, that they are sensible. What is the ultimate
nature of the sensible or the phenomenal, what is their reality,
is a question wholly outside the province of sense. The questions of
ultimate nature, of reality, are questions of metaphysics, and hence
are to be decided by the reason, not by the senses. And Leibniz goes
on to say that the truthfulness of the senses, since it concerns only
the sensible, consists in the reciprocal agreement of sensible facts,
and in that we are not deceived in reasoning from one to another. An
isolated sense-experience could not be said to be either true or
false, real or illusory. It would be true that it was experienced,
and that is all that could be said about it. But since our experiences
are not thus separated, but have a certain order, there arises what
we may call sensible reality and illusion. When the order between
two facts remains the same "in different times and places and in the
experience of different men," we call these facts real. If, however,
our experience cannot be repeated by ourselves or by other men when
the same conditions (that is, connections) are present, it is unreal,
or false. It is thus "the _relation_ of phenomena which guarantees
truth of fact regarding sensible objects." Constancy, regularity,
justify us in ascribing reality; chaotic change and lack of orderly
connection are a sign of unreality. Even our dreams have a reality; for
they have their connections and place in experience. If we understood
their connections we should even be able to explain their apparent
lack of connection with the rest of experience. Leibniz thinks that
both the Academicians and Sceptics and their opponents erred in
attempting to find greater reality in sensible things than that of
regular phenomena. Since our observations and judgments upon sensible
phenomena are of such a nature that we can predict future phenomena and
prepare for them, we have all the reality in them that can be had or
asked for. Even if it be granted possible (as it must be on this basis)
that, metaphysically speaking, sense-experience is only a connected
dream, it yet has a sufficient reality; for we are not deceived in
the measures taken with reference to phenomena, provided that we act
on the ground of their observed harmonies and relations. Thus while
we are obliged to admit that our senses inform us that there are hard,
passive, extended, indivisible things, not perfectly continuous and not
intellectual in their nature, and we know on metaphysical grounds that
this information is not correct, we cannot say that our senses deceive
us, for sense makes no statements regarding such matters. It is our
reason that errs if it takes the information that the senses give as if
it were a declaration of reason itself. Sensible things have all the
reality necessary for this range of experience,--_practical_,--such
regularity of co-existence and sequence as allows us to act without
being led astray.
But if we regard sense-phenomena not merely in their connection with
one another, but in their dependence upon the absolute realities, we
have still better justification for their comparative reality. These
phenomena are consequences of necessary and eternal truths. One endowed
with a perfect knowledge of such truths would be able to deduce, _a
priori_, the phenomena from them. The reality of sensible phenomena
thus consists not merely in their connection with one another, but in
the fact that they are connected as the laws of the intelligible world
require. They follow not only rules of co-existence and sequence;
but these rules may be brought under general laws of motion, which
in turn may be deduced from geometrical principles. These latter,
however, are _a priori_; they are truths which are grounded in the very
intelligence of God. The sensible has its basis in the ideal. To state
the same fact in another way, all sensible phenomena occur in time
and space; or rather, time and space are the orders, the relations,
of phenomena occurring and existing. But, as we have just seen, time
and space are ideal. A relation, as Leibniz points out, being neither
attribute nor accident, cannot be _in_ the things which it relates,
as their possession. In his own words, it cannot be conceived as if
it had one leg in one object, the other leg in the other. A relation
is not a material bond, running through or cementing objects; it
is ideal, existing in the mind. And while it is true that space and
time are the relations of objects and events, it is also true that
if all objects and events were annihilated, space and time would
continue to have their ideal existence in the intelligence of God as
the eternal conditions of phenomena. They thus form the links between
absolute reality and the reality of sensible existence. The principle
of sufficient reason forms another link. It may be recalled that in
discussing Leibniz's theory of volition we found that the will of God
in relation to the sensible world is always determined by the choice of
the better; that in this consists the controlling reason and regulative
principle of all that occurs and exists. Thus for every fact in the
sensible world there is connection with "metaphysical," or absolute,
reality, not only through the medium of the intellectual relations
of time and space, but through the dynamic intermediary of the divine
will acting in accordance with the divine reason. Sensible facts have,
then, a reality, but a dependent one. There would be no _contradiction_
involved if they were not what they actually are.
We may sum up the matter by saying that the reality of sensible
phenomena consists in the constancy of the mutual order in which they
exist, and in the dependence of this order upon the divine Intelligence
and Will. In this respect, at least, Leibniz resembles the young Irish
idealist, Berkeley, who only seven years after Leibniz wrote the "New
Essays" composed his "Principles of Human Knowledge," urging that the
immediate reality of sense-phenomena consists in their "steadiness,
order, and coherence," "in a constant uniform working," and that this
"gives us a foresight which enables us to regulate our actions for the
benefit of life." It was Berkeley also who wrote that their ultimate
reality consists in their being ideas of a Divine Spirit. This was six
years before the death of Leibniz. Yet it does not appear that Berkeley
knew of Leibniz, and the only allusion to Berkeley which I have
found in the writings of Leibniz shows that Leibniz knew only of that
caricature of his views which has always been current,--that Berkeley
was one who denied the existence of any external world. What he writes
is as follows: "As for him in Ireland who questions the reality of
'bodies,' he seems neither to offer what is rational, nor sufficiently
to explain his own ideas. I suspect that he is one of those men who are
desirous of making themselves known through paradoxes."