aware: there are ideas which we do not see or handle, or smell or taste,
but of which we are nevertheless distinctly conscious. Thought has its
movement, ideas have their co-existence and sequences, the association
of ideas has its laws. There is a uniformity of human nature as well as
of external nature; there are conditions under which certain actions are
always performed, and without which they would never be done. Whether
the body of propositions in which these conditions are formulated be
accorded or denied the name of science, matters little. But it is
difficult to see what are the so great differences between these
phenomena and sense-phenomena that make the latter amenable and the
former insusceptible to scientific treatment. Is it that ideas are
invisible? So is weight, yet the gravitation formula is scientific. Is
it that thought is impalpable? So is colour, so is sound--yet there are
optics and acoustics.
Be this as it may, what makes things material susceptible to scientific
treatment is a quality which is not peculiar to them, but which is
shared by them in common with things immaterial: it is that they are
objects of which the mind is immediately aware, phenomena present to
some consciousness, and that they are phenomena which appear in
consciousness as co-existent and successive in certain definite uniform
modes which can be detected by thought and formulated in general
propositions, or laws.
If the theory of evolution comprehends all things, mind and morals as
well as matter and motion; if the law of continuity connects all things
together, immaterial as well as material, in a process which moves
without break or interruption; it is because all things agree in the
fact that they are presented (whether in sense or in idea) to the mind,
and because they are presented in the continuity of consciousness.
But the object of the scientific mind is not to observe and record all
the phenomena presented to it in the continuity of consciousness. On the
contrary, it neglects and rejects many; but always with a purpose, viz.
that of ascertaining and describing, as precisely as possible, the
conditions under which a given co-existence or sequence occurs (and
therefore may be expected to recur) and without which it fails to occur.
In other words, science assumes that everything has a cause, and that in
accordance with the uniformity of nature what has happened once will
happen again in the same circumstances; that a cause will, in the
absence of counteracting causes, produce its effect. Without these
assumptions science cannot treat of any subject: no department of
knowledge can be dealt with scientifically if these assumptions are not
admitted with regard to that department. On the other hand, if by the
aid of these assumptions we are enabled to reduce any set of phenomena
to law and order, our success is of itself sufficient ground for
regarding the assumptions as warrantable and justifiable. For science,
at any rate, the only question is whether as a matter of fact they do
enable us to determine under what conditions given co-existences or
sequences will ensue, or what conditions such a co-existence or sequence
necessarily implies.
With regard to human activity, mental and physical, it is plain matter
of fact that such uniformities of sequence and co-existence not only can
be but are demonstrated to prevail; and the extension of the scientific
principle of cause and effect to the domain of human will and action is
scientifically justified. The comparative sciences which deal with man
and his works and words--archæology, anthropology, philology--are
perpetually engaged in demonstrating, with fresh proofs every day, the
uniformity of human nature: in similar circumstances men have always
behaved in similar ways. To satisfy the same needs, they have
manufactured similar instruments at similar stages of development: flint
arrow-heads from Mexico or Japan resemble those taken from British
barrows; the pottery of early Greece is hard to distinguish from that of
Peru; the purpose of many stone implements of unknown antiquity has been
discovered by a comparison of the use to which similar tools are put by
savages still existing. That man's words, as well as his works, exhibit
law, order, and uniformity in their growth, as well as in their phonetic
decay, is shown by the science of comparative philology. That in the
face of the same problems similar analogies have been used to produce
similar solutions, is revealed by comparative mythology: the
imagination, which might have seemed most free to throw off the trammels
of law and of monotonous uniformity, falls in similar circumstances into
very similar grooves.
If the will of man is not revealed in the things which he makes, in the
words which he speaks, and the thoughts which he thinks, it is difficult
to know where to look for its manifestation. If, on the other hand, it
is manifested in these ways, then, whether it be free or not, it is
clearly uniform in its action; and the extension to it of the law of
causation seems fully justified by the results.
The recognition of the universality of the law of causation must not,
however, be supposed to carry with it any implication that there are no
differences between, say, the organic and inorganic, or that the laws of
the one are identical with or deducible from those of the other; the
association of ideas may be a scientific and established fact, and yet
not obey the same laws as the adhesiveness of material substances. What
unites all things into a continuous, coherent, and systematic cosmos,
into a scientific whole, is first the fact that, whether phenomena in
sense or phenomena in idea, they are all objects of thought; and next
the fact that they all exhibit the universality of causation and the
uniformity of nature.
Whether this uniformity which binds man and nature into one consistent
whole is a uniformity of will or a uniformity of necessity, is quite
another question. It is a metaphysical and not a scientific inquiry; and
the metaphysical answer, whatever it may be, is one for which science
does not and need not pause. So long as nature is granted to be uniform,
it matters not to science whether the uniformity is of necessity or is
freely willed. In either case the sequences or co-existences described
by science will continue, under the circumstances described, to happen
as described.
It is, however, commonly assumed that actions which are uniform are, by
their very uniformity, proved to be necessitated; and that unless what
happens was bound to happen, there can be no uniformity and no science.
Hence on the one hand the recognition of the freedom of the will has
been denounced as fatal to all scientific conceptions of human nature;
while on the other hand the uniformity of human nature and action has
been denied as being inconsistent with the freedom of the will. The one
side has pointed to one set of facts, which prove irresistibly that men
do will the same thing under the same circumstances. The other side has
pointed to the equally undeniable fact of our consciousness of freedom.
The essential feature in our consciousness of freedom is our conviction
that in the present we can do or abstain from doing a contemplated
action, and in the past, though we did the thing, we might have
abstained from it or have done something else. Now, whether this
possibility that what took place might not have taken place is a real
one or only a delusion, matters not to science. If real and true, it is
indeed fatal to one particular metaphysical theory, viz. that every
event which ever occurred was bound to occur and could not have happened
otherwise; but it leaves every truth of science, every one of those
concise descriptions of what takes place under given circumstances,
absolutely intact. The freedom of the will is anathematised in the name
but not in the interests of science.
That becomes clear when we reflect that the laws of science are, and do
not pretend to be more than, hypothetical statements. The gravitation
formula does not state that bodies do as a matter of fact actually fall
at the rate of sixteen feet in the first second, and so on. The
statement, if made, would be untrue: a feather floats much more slowly
to the ground. Still less does the formula affirm that all bodies move
towards each other--and for a very good reason: many bodies are at rest.
The formula makes no definite statement as to what actually does occur:
it merely states what would or will happen under certain circumstances;
and it is doubly or trebly hypothetical. First, it asserts conditionally
that if, and only if, bodies are free to move, they will tend to move
towards each other at the rate of sixteen feet in the first second, and
so on. Next, even if this condition be fulfilled in a particular case,
and a given body is free to move, say, towards the earth, the law of
gravitation does not assert that the body will absolutely, or
unconditionally, or of necessity fall sixteen feet in the first second:
it only affirms that the body tends to move at that rate, and the word
"tends" conveys in its meaning a second hypothesis. What is meant by
saying that a body tends to fall, or tends to move in a straight line,
is simply that the body will fall or move in the direction or at the
rate mentioned, provided that nothing happens to prevent it. The law of
gravitation then, like every other law of science, from the very terms
in which it is stated, contains two hypotheses: _if_ bodies are free to
move, then they _tend_ to move at a certain rate. Further, like every
other law of science, it is based on a third hypothesis, which, as it is
assumed by all scientific laws, is not expressly referred to by any.
That third hypothesis is that nature is uniform: if a body is free to
move it will, in the future as in the past, tend to move at a certain
rate, provided that nature is uniform.
Now, throughout all this, it is obvious that science knows nothing about
"necessity." Indeed, it is obvious that science, by the trebly
hypothetical form of all its laws, has taken particular pains to avoid
prejudging the question whether what happens was bound to happen. As we
have already said, science takes care to frame its statements in such a
way that they are quite independent of metaphysical theory, and will
remain as true within their limits if the theory of necessity prove
erroneous as they will if it turns out to be correct.
Nor can it be said, thus far, that the laws of science lead us to the
theory of necessity as their logical conclusion. It may be true that if
I walk over a precipice I shall fall to the bottom, in accordance with
the law of gravitation. But it does not logically follow that therefore
I must walk over. It may be true that a suspension bridge will fall in
the same way, if the supports be removed; but it does not follow that
they are therefore bound to give way. It may be true that if nature is
uniform certain sequences will happen; but it does not therefore follow
that nature must be uniform. In other words, the theory of necessity, if
true, cannot be based on science, but must rely on some metaphysical
considerations. Science does not undertake to prove even that nature is
uniform, much less that it is uniform of necessity. The opposite theory,
that the uniformity of nature or of human nature is due to the action
of a will freely manifesting itself as uniform, may be considered
superfluous from the scientific point of view. But the theory of
necessity from the same point of view is equally superfluous. As long as
events do happen uniformly, science has all she wants--whether their
uniformity is of will or of necessity is for her quite a superfluous
question. And if science were all that man wanted, these rival
metaphysical theories would be of no interest to him either. But the
persistency of the attempt to extract some support for the metaphysical
theory of necessity out of the facts of science shows that men of
science, being men, must have their metaphysics.
Are there, then, other facts of science, or assumptions essential to
science, which require the metaphysical theory of necessity as their
presupposition or entail it as their natural consequence? Probably the
reply will be that there is one such principle: that of the Universality
of the Law of Causation. The assumption that everything _must_ have a
cause may be on the part of science a pure assumption, and one which,
like the Uniformity of Nature, cannot be proved by science; but it does,
it may be said, assume the existence of a necessity in things.
It does, it may be replied, but whether the necessity which science
assumes is the same as that maintained by the metaphysical theory in
question, may be doubted. The metaphysical theory is that everything
which happens happens of necessity, and could not have happened
otherwise than it did. The assumptions which science makes with regard
to causation are that nothing can happen unless the conditions requisite
to its production are fulfilled, and that when those conditions are
present the result necessarily follows. The question is whether this
scientific necessity is the same as that metaphysical necessity; or, if
they are not the same, whether either is a logical consequence from the
other.
They are not the same: the scientific assumption is hypothetical, the
metaphysical absolute. The former says that things will happen in one
way, if certain conditions are fulfilled, in another if they are not;
the latter that they absolutely must happen in this way, and not in
that; and that it is an illusion to imagine that they can happen
_either_ this way _or_ that. Science allows us the alternative; the
metaphysical theory declares that the alternative is an impossibility or
an illusion. The metaphysical theory may be right, but it is not the
same thing as the scientific assumption. Neither can it be exhibited as
a logical presupposition of or consequence from the scientific
assumption. From a hypothetical "if" you cannot logically get an
absolute "must." It may be a scientific truth that, if an electric spark
is passed through two atoms of hydrogen and one of oxygen, a drop of
water will be formed. But it does not follow that therefore an electric
spark must be passed through them.
It is obvious that the difference between science and metaphysics in the
matter of necessity is that, whereas science cautiously says, "If
certain conditions are fulfilled, certain results will ensue,"
metaphysics boldly says, "The conditions on which the whole future
depends are already absolutely fixed." Once more, this metaphysical
theory may be true; but, if so, it is not from science that it derives
its truth. The transition from the "if" of science to the "must" of
metaphysics is illogical, though not unnatural, and is facilitated by a
certain amount of obscurity, which can be thrown over it by drawing
illustrations from the past. Thus, if an event has already taken place,
we may infer with certainty from the fact of its occurrence that the
conditions necessary to produce it were realised. And as each of those
conditions must have had a cause, we can infer again that the conditions
requisite to produce them were fulfilled. And so we may travel back _ad
infinitum_ along a never-ending chain of cause and effect, always moving
from one fixed and necessitated event to another event equally
necessitated and fixed. Thus the whole past history of the universe may
be exhibited as a necessary sequence of events; and the inference may be
drawn, and for the purposes of the theory of metaphysical necessity must
be drawn, that because the occurrence of an event proves that the
conditions required for its production were realised, therefore they and
they alone were bound to be realised. Yet this is simply our old
familiar _non sequitur_ thrown into the past tense. It is true that if I
walk over a precipice I shall fall, according to the law of gravitation.
But I am not therefore bound to walk over. It is true that the man who
fell over the cliff obeyed the law of gravity. But we cannot infer
either from the law of gravitation or from the fact of his falling that
he was bound to fall. We can infer that the conditions requisite to
produce the fall were present, but we cannot infer from the fall that
they were bound to be present. It may be quite true that they were bound
to be present, but the effect which followed on them cannot be alleged
either as the cause or the proof of such necessity. We must look for the
reason of the necessity--if there be any necessity in the
case--elsewhere. Shall we, then, say that the conditions of the fall
were themselves effects of prior causes, without which they would not
have happened? That again is true, but the fact that Z would not have
happened had not Y preceded, is not in itself any proof that Y was bound
to happen. And so we may travel back _ad infinitum_ along the
never-ending chain of cause and effect without ever finding ourselves in
a position to infer from the law that everything must have a cause,
that this cause was bound to operate rather than that. The occurrence of
Z is no proof that Y was bound to happen, nor is the fact that Y really
happened any proof that its cause X was bound to occur--and so we may
work back to the beginning of the alphabet. The fact that B took place
shows that A actually occurred, but not that A, rather than A₁ or A₂,
was bound to occur. And if A is the beginning, what was the nature of
the necessity (prior to the beginning of things) which determined in
favour of A rather than A₁ or A₂?
We may indeed say, if we like--since no one can prevent us from saying
things without proof or probability--that the mere fact that A happened
shows that it was bound to happen. But then we might just as well have
said it of Z, and saved ourselves the trouble of going through so much
alphabet to get so little result. We might just as well say that as the
explosion or the accident _did_ happen as a matter of fact, it could not
possibly have been prevented: Z was bound to happen under the
circumstances, therefore the circumstances could not have been altered;
only one result was possible under the conditions, therefore no other
conditions were possible.
Or--to go back to the beginning of the alphabet once more--we may say
with science that we are content with the fact that A did happen, or,
since science does not profess to take us back to an absolute beginning
(force and matter being eternal and without beginning), let us say we
may, like science, be content with the fact that K can be shown to have
happened; but whether K, rather than K₁ or K₂, was bound to occur
there is nothing in science to show. If we take up this, the scientific,
attitude, two consequences follow. First, there is nothing in science to
require or countenance the metaphysical theory of necessity. Next, what
is true of K is equally true of L or M or Z. The fact that L or M or Z
occurred proves that the conditions did combine in the way necessary to
produce L or M or Z, not that they were bound to combine in that way and
could not have combined so as to produce L₁ or L₂, or Z₁ or Z₂ or
Z₃.
Perhaps it may be said that the following is the proper way of stating
the case: We have reason for believing that, as a matter of scientific
necessity, if L is at work it can only produce M, and not M₁ or M₂
(the application of a light to a barrel of gunpowder can have only one
result). But L was at work, therefore M alone could result. Quite true,
but that does not show that the light was bound to be applied, or that
the powder might not have been damp. In fine, the moment the conditions
requisite for the explosion are combined, the explosion is necessary, M
is the only possible result; but until then the explosion is not
necessary, and the result may be M₁, or M₂, or M₃. A cause (_i.e._
the conditions combined) can only have one effect; but until it has
that effect it is not the cause, and may never be. Pre-existent causes,
which must inevitably produce predetermined effects, are figments of the
metaphysical imagination. Conditions which may, and, subject to the
trebly hypothetical laws of science, will combine in certain ways are
scientific facts.
In fine, the Uniformity of Nature, in the sense in which Nature is
assumed, both by science and by common sense, to be uniform, simply
amounts to the assumption that under the same conditions the same
consequences will ensue. But this uniformity neither requires nor
entails necessity. The very form chosen by science for the expression of
scientific laws proclaims the fact: "_If_ bodies are free to move,"
"_if_ counteracting causes be absent," "a body _tends_ to move in the
same straight line." Whatever necessity is introduced into the truths of
science thus expressed is obviously imported from without, and is no
part of science. We may, if we choose, read necessity into science, but
there is no warrant in science for doing so. Science is absolutely
without prejudice on this point. If everything that happens happens of
necessity, the gravitation formula will receive no accession to its
truth. If there be no necessity in the case, each and every truth of
science remains valid as long as the same consequences do ensue in the
same circumstances.
Since, then, science observes an armed neutrality in this dispute, and
is concerned only to guard that assumption of the uniformity of nature
which is vital to her existence, we must turn elsewhere for a decision
of the question.