NECESSARY TRUTH IS PROGRESSIVE.
OBJECTIONS CONSIDERED.
The doctrine that necessary truth is progressive is a doctrine very
important in its bearing upon the nature of the human mind; and, as
I conceive, in its theological bearing also. But it is a doctrine to
which objections are likely to be made from various quarters, and I
will consider some of these objections.
1. Necessary truths, it will be said, cannot increase in number. New
ones cannot be added to the old ones. For necessary truths are those of
which the necessity is plain and evident to all mankind--to the common
sense of man; such as the axioms of geometry. But that which is evident
to all mankind must be evident from the first: that which is plain to
the common sense of man cannot require scientific discovery: that which
is necessarily true cannot require accumulated proof.
To this I reply, that necessary truths require for their apprehension
a certain growth and development of the human mind. Though it is seen
that they are necessarily true, this is seen only by those who think
steadily and clearly, and to think steadily and clearly on any kind
of subject, requires time and attention;--requires mental culture.
This may be seen even in the case of the axioms of geometry. These
axioms are self-evident: but to _whom_ are they self-evident? Not to
uncultured savages, or young children; or persons of loose vague habits
of thought. To see the truth and necessity of geometrical axioms, we
need geometrical culture.
Therefore that any axioms are not evident without patient thought and
continued study of the subject, does not disprove their necessity.
Principles may be axiomatic and necessary, although they require time,
and the progress of thought and of knowledge, to bring them to light.
And axioms may be thus gradually brought to light by the progress of
knowledge.
Nor is it difficult to give examples of such axioms, other than
geometrical. There is an axiom which has obtained currency among
thoughtful men from the time that man began to speculate about himself
and the universe:--_E nihilo nil fit_: Nothing can be made of nothing.
No material substance can be produced or destroyed by natural causes,
though its form and consistence may be changed indefinitely. Is not
this an axiom? a necessary truth? Yet it is not evident to all men
at first, and without mental culture. At first and before habits of
steady and consistent thought are formed, men think familiarly of the
creation and destruction of matter. Only when the mind has received
some philosophical culture does it see the truth and necessity of the
axiom of substance, and _then_ it does see it.
And the axioms on which the science of mechanics rests, that the cause
is measured by the effects, that reaction is equal and opposite to
action, and the like,--are not these evident to a mind cultivated by
steady thought on such subjects? and do they not require such culture
of the mind in order to see them? Are they not obscure or uncertain
to those who are not so cultured, that is to common thinkers: to the
general bulk of mankind? Thus then it requires the discipline of the
science of mechanics to enable the mind to see the axioms of that
science.
And does not this go further, as science and the careful study of
the grounds of science go further? To a person well disciplined in
mechanical reasoning it has become, not a conclusion, but a principle,
that in mechanical action what is gained in power is lost in time:
or that in any change, the force gained is equal to the force lost,
so that new force cannot be generated, any more than new matter, by
natural changes. Is this an axiom? a necessary fundamental truth? It
appears so to at least one great thinker and discoverer now alive
among us. If it do not appear so to us, or not in the same sense,
may not this be because we have not yet reached his point of view?
May not the conviction which is now his alone become hereafter the
conviction of the philosophical world? And whatever the case may be
in this instance, have there not been examples of this progress? Did
not Galileo and the disciples of Galileo reduce several mechanical
principles to the character of necessary truths, after they had by
experiment and reasoning discovered them to be actually true? And
have we not in these cases so many proofs that necessary truth is
progressive, along with the progress of knowledge?
2. But, it will be said, the necessary character claimed for such
truths is an illusion. The propositions so brought into view are really
established by observation: by the study of external facts: and it is
only the effect of habit and familiarity which makes men of science,
when they well know them to be true, think them to be necessarily true.
They are really the results of experience, as their history shows; and
therefore cannot be necessary and _à priori_ truths.
To which I reply: Such principles as I have mentioned,--that material
substance cannot be produced or destroyed--that the cause is measured
by the effect--that reaction is equal and opposite to action: are not
the results of experience, nor can be. No experience can prove them;
they are necessarily assumed as the interpretation of experience.
They were not proved in the course of scientific investigations, but
brought to light as such investigations showed their necessity. They
are not the results, but the conditions of experimental sciences.
If the Axiom of Substance were not true, and were not assumed, we
could not have such a science as Chemistry, that is, we could have
no knowledge at all respecting the changes of form of substances.
If the Axioms of Mechanics were not true and were not assumed, we
could have no science of Mechanics, that is, no knowledge of the laws
of force acting on matter. It is not any special _results_ of the
science in such cases; but the _existence_, the _possibility_, of
any science, which establishes the necessity of these axioms. They
are not the consequences of knowledge, acquired from without, but
the internal condition of our being able to know. And when we are to
_know_ concerning any new subject contained in the universe, it is not
inconceivable nor strange that there should be new conditions of our
knowledge.
It is not inconceivable or strange, therefore, that as new sciences
are formed, new axioms, the foundations of such sciences, should come
into view. As the light of clear and definite knowledge is kindled in
successive chambers of the universe, it may disclose, not only the
aspect of those new apartments, but also the form and structure of the
lamp which man is thus allowed to carry from point to point, and to
transmit from hand to hand. And though the space illumined to man's
vision may always be small in comparison with the immeasurable abyss of
darkness by which it is surrounded, and though the light may be dim and
feeble, as well as partial; this need not make us doubt that, so far as
we can by the aid of this lamp, we see truly: so far as we discern the
necessary laws of the universe, the laws are true, and their truth is
rooted in that in which the being of the universe is rooted.
And, to dwell for a moment longer on this image, we may also
conceive that all that this lamp--the intellect of man cultivated by
science,--does, by the light which it gives, is this--that it dispels a
darkness which is dark for man alone, and discloses to him some things
in some measure as all things lie in clear and perfect light before the
eye of God. To the Divine Mind all the laws of the universe are plain
and clear in all their multiplicity, extent and depth. The human mind
is capable of seeing some of these laws, though only a few; to some
extent, though but a little way; to some depth, though never to the
bottom. But the Human Mind, can, in the course of ages and generations,
by the long exercise of thought, successfully employed in augmenting
knowledge, improve its powers of vision; and may thus come to see more
laws than at first, to trace their extent more largely, to understand
them more thoroughly; and thus the inward intellectual light of man may
become broader and broader from age to age, though ever narrow when
compared with completeness.
3. Is it strange to any one that inward light, as well as outward
knowledge, should thus increase in the course of man's earthly career?
that as knowledge extends, the foundations of knowledge should expand?
that as man goes on discovering new truths, he should also discover
something concerning the conditions of truth? Is it wonderful that
as science is progressive the philosophy of science also should be
progressive? that as we know more of everything else, we should also
come to know more of our powers of knowing?
This does not seem to have been supposed by philosophers in general;
or rather, they have assumed that they could come to know more about
the powers of knowing by thinking about them, even without taking
into account the light thrown upon the nature of knowledge by the
progress of knowledge. From Plato downwards, through Aristotle,
through the Schoolmen, to Descartes, to Locke, to Kant, Schelling and
Hegel, philosophers have been perpetually endeavouring to explore
the nature, the foundations, the consequences of our knowledge. But
since Plato, scarcely one of them has ever proceeded as if new light
were thrown upon knowledge by new knowledge. They have, many or all
of them, attempted to establish fundamental truths, some of them new
fundamental truths, about the human mind and the nature and conditions
of its knowledge. These attempts show that they do not deny or doubt
that there may be such new fundamental truths. Such new fundamental
truths respecting the human mind and respecting knowledge must be, in
many cases at least, (as it will be seen that they _are_, on examining
the systems proposed by the philosophers just mentioned,) seen by
their own light to be true. They are _new axioms_ in philosophy. These
philosophers therefore, or their disciples, cannot consistently blame
us for holding the possibility of new axioms being introduced into
philosophy from age to age, as there arise philosophers more and more
clear-sighted.
4. But though _they_ have no ground for rejecting _our_ new axioms
merely because they are new, _we_ may have good ground for doubting
the value of _their_ new axioms, that is, of the foundations of their
systems; because they are new truths about knowledge gathered by
merely exploring the old fields of knowledge. We found our hopes of
obtaining a larger view of the constitution of the human mind than the
early philosophers had, on this:--that we obtain our view by studying
the operation of the human mind _since their time_; its progress
in acquiring a large stock of uncontested truths and in obtaining
a wide and real knowledge of the universe. Here are new materials
which the ancients had not; and which may therefore justify the hope
that we may build our philosophy higher than the ancients did. But
modern philosophers who use only the same materials as the ancient
philosophers used, have not the same grounds for hope which we have. If
they borrow all their examples and illustrations of man's knowledge of
the universe, from the condition of the universe as existing in Space
and Time, that is, from the geometrical condition of the universe, they
may fail to obtain the light which might be obtained if they considered
that the universe is also subject to conditions of _Substance_, of
_Cause_ and _Effect_, of _Force_ and _Matter_: is filled with _Kinds_
of things, in whose structure we assume _Design_ and _Ends_; and so on;
and if they reflected that these conditions or _Ideas_ are not mere
vague notions, but the bases of sciences which all thoughtful persons
allow to be certain and real.
It is then, as I have said, from taking advantage of the progressive
character which physical science, in the history of man, has been
found to possess, that I hope to learn more of the nature and
prospects of the human mind and soul, than those can learn who still
take their stand on the old limited ground of man's knowledge.
The knowledge of Geometry by the Greeks was the starting-point of
their sound philosophy. It showed that something might be certainly
known, and it showed, in some degree, how it was known. It thus
refuted the skepticism which was destroying philosophy, and offered
specimens of solid truth for the philosopher to analyse. But the
Greeks tried to go beyond geometry in their knowledge of the universe.
They tried to construct a science of Astronomy--of Harmonics--of
Optics--of Mechanics. In the two former subjects, they succeeded to
a very considerable extent. The question then arose, What was the
philosophical import of these new sciences? What light did they throw
on the nature of the universe, on the nature of knowledge, on the
nature of the human mind? These questions Plato attempted to answer. He
said that the lesson of these new sciences is this:--that the universe
is framed upon the _Divine Ideas_; that man can to a certain extent
obtain sight of these Ideas; and that when he does this, he _knows_
concerning the universe. And again, he also put the matter otherwise:
there is an _Intelligible World_, of which the Visible and Sensible
world is only a dim image. _Science_ consists in understanding the
Intelligible World, which man is to a certain extent able to do, by the
nature of his understanding. This was Plato's philosophy, founded upon
the progress which human knowledge had made up to his time. Since his
time, knowledge, that is science, has made a large additional progress.
What is the philosophical lesson to be derived from this progress,
and from the new provinces thus added to human knowledge? This is a
question which I have tried to answer. I am not aware that any one
since Plato has taken this line of speculation;--I mean, has tried
to spell out the lesson of philosophy which is taught us, not by one
specimen, or a few only, of the knowledge respecting the universe which
man has acquired; but by including in his survey all the provinces of
human knowledge, and the whole history of each. At any rate, whatever
any one else may have done in this way, it seems to me that new
inferences remain to be drawn, of the nature of those which Plato drew:
and those I here attempt to deduce and to illustrate.