bone, muscle, nerve, and cellular tissue, while observational science
is capable of recognizing no more than these, so that, if there be any
thing more, it is quite beyond the range of physical science, and within
the territory of mental philosophy. Here then, is preparation for
conflict, which may be accepted as inevitable, because of the advance of
science. The occasion for this expectation should, however, be fully
understood. Its certainty may be maintained on two obvious grounds. The
first is concerned with the history of scientific progress. Science is
pushing its way up the extended scale of existence with no exact
knowledge of its own limits; knowing what its achievements have been,
animated to a high degree by the vastness of the problems still before
it, but knowing nothing quite definite as to its own boundaries. The
aggressive force of science at such a stage must be great. On the other
hand, there is a large body of settled conviction, which has swayed men
and moulded society in all ages, which is an opposing force operating on
that very line along which science is advancing, and which must be
encountered whenever man's place in the universe becomes the subject of
inquiry. This opposing conviction is not necessarily religious in type,
though it is supported by the whole range of thought concerned with the
supernatural. The conviction here referred to, as lying more obviously
across the path on which science is travelling, is that concerned with
the personality of man, with the rights and responsibilities of
individuals, implying accepted conclusions on which the government, and
police, and administration of affairs in every nation are based. It
must, then, be clearly recognized that the conflict anticipated as
inevitable is the conflict of knowledge of one order, with knowledge of
a different order. It is conflict of knowledge obtained by the slow and
difficult processes available to science, with knowledge possessed by
all, applied in the regulation of individual and social life, and
systematized in the annals of mental philosophy; or, we may more nearly
describe the condition of matters by saying that the occasion of
conflict is the determination of science to include all within its own
area, rather than the possession of actual knowledge as to the highest
order of life, for science is only seeking, and can not profess to have
found, an explanation of the functions of human life, as it can profess
to have done in the case of lower orders. There could, therefore, be no
more mistaken representation of the pending conflict than the allegation
that it is a conflict of knowledge with ignorance. To put it in the best
light for science, it is the conflict of one kind of knowledge with
another; but there is a nearer approach to accuracy if we say that the
conflict is occasioned by the _want of verified conclusions_ within the
boundaries of science itself, in contrast with very definite conclusions
belonging to men generally, and verified by practical tests which
scientific men can not refuse. It is not essential to the point, but may
be of consequence in view of the range of application belonging to this
inquiry, to remark that religious thought is not itself directly
involved here; nevertheless, religious thought is deeply concerned in
the issue of the conflict.
Having thus briefly indicated the occasion of the conflict, and the
contending forces, it is desirable to find the standpoint of science.
The nature and origin of life having been passed as problems for which
no solution has yet been found, science has concentrated on the
functions of the various portions of each organism, and on the
contrivances for its protection and continuance in the world; and still
more in advance, on the laws favoring the development of species. From
outward form it has passed to inward structure, and pressing still more
closely towards the secrets of life has endeavored to ascertain by
microscopic investigation what provision has been made for maintaining
the vital processes involved in the action of organism. Travelling up
the advancing orders of animate existence, science has discovered a
uniform plan adapted to varying complexity of structure. Thus entered
and far advanced on the course of investigation, science sees no limit
to its field of inquiry save the limits of organism itself. What has
already been achieved, gives full warrant for the claim of inclusion, in
which all scientific men naturally concur, and with which men generally
will readily agree. This agreement, however, lies on the very boundary
line of disagreement and dissension. Immediately when an attempt is made
to set forth what is implied, it becomes clear that some scientific men
include very large expectations as to what science is yet to
accomplish, while others, showing more of the caution of the scientific
spirit, decline to commit themselves to dogmatic assertions. Up to the
line of agreement indicated we are dealing with science; beyond that
line, where we come upon disagreements, we are not dealing with science,
but with the comparative sanguineness or caution of scientific men.
What we have before us as clearly admitted on all sides is that human
life presents the common characteristics of organic life, and is
subjected to the ordinary laws of organism. The problem with which we
have now to deal in view of this admission is this,--How far do the
functions of organism account for the universally recognized
characteristics of human life?
In facing this problem there are not a few scientific inquirers who look
upon the mere raising of it as a claim to include all that belongs to
human nature within the realm of physical science. They have allowed
themselves to regard the two things as interchangeable, and all their
researches are in their view so involved in this identification, that
they resent the challenging of it, as if it implied antagonism to
science. But the scientific inconsistency of this is easily shown. That
science must extend its investigations to human organism, admits of no
doubt; that by means of this investigation all the phenomena of human
life will be traced to organism, is the very thing to be proved, and
until established on clear and full evidence is not to be regarded
otherwise than problematic. If we are in this matter to be influenced by
regard to the slow and difficult procedure in cases of much greater
simplicity, we shall be guarded in the utterance of expectations; if we
make account of the enormous difficulties to be encountered in arranging
the facts to be explained, we shall be still more guarded; and if we
remember that the practical demands of life must all be met day by day
without waiting for science as an aid, it will not appear strange that
the non-scientific thinker regards the whole scientific investigation as
wide of the sphere in which questions of self-government are settled,
even though this view seems to affirm, without knowledge of both sides,
that there is a sphere belonging to human life into which science can
not enter.
Still, it must be allowed that in the pathway of science nothing is to
be foreclosed, and no area, whether large or small, is to be shut off on
which the appliances of science can be brought to bear. Science can not
exclude man from the range of investigation; can not on any warrant
supplied by the conditions of its own procedure, draw a line within the
circumference of nature, even though it may be constrained to allow that
there are many things within nature of which it can offer no
explanation.
That science has by recent research done much to explain phases of human
activity previously unexplained, may be clearly shown. The modification
of previously received opinion may be indicated thus,--that many forms
formerly regarded as in the true sense voluntary, and so described in
the life not only of man, but also of the higher animals, can be
explained by the action of brain and nerve. This involves a considerable
extension of the area of the mechanical in human action, and a
considerable restriction of the area of the voluntary. In seeking to
indicate roughly the form of this restriction, we may find enough for
our purpose in the distinction between what we may describe as
_muscular action_, and what we would more naturally denominate _personal
conduct_. This contrast will serve throughout, as we proceed to estimate
the explanations which science has reached in dealing with the
characteristics of human life.
The proved superiority of brain and nerve in man affords an adequate
explanation of his generally recognized superiority in the variety of
the forms of his muscular activity. In mere muscular power man can not
compete with the more powerful animals. His practical superiority is
seen in manipulation and the vastly greater variety of occupations to
which he can turn; and in the greater wisdom he has for self-government.
Leaving meanwhile out of account comparative intelligence, we have only
to consider the superior use man has of the general sensibilities of the
body, and of the special senses of touch and sight; the greater variety
of the joints and muscles in his body; the more complicated arrangements
of his nerve system; and the relation of all these in a single economy,
in order to perceive a distinct phase of the superiority of man,
sufficiently accounted for by clearly recognized facts, anatomical and
physiological. In a multitude of well-known forms of action, of which
the mechanical arts afford illustration, man can do what can not be
attempted by lower forms of organism.
Another step higher is taken by the advance of physiological science,
involving an explanation of _acquired aptitudes_. The interaction of
sensibility and motor activity has been shown to be great. A message
conveyed along a sensory line is readily transferred to a motor line;
the sense of touch becomes a natural guide to familiar forms of action;
a form of sensibility may thus be connected with a given range of motor
apparatus, just as the history of the blind illustrates how much more
can be accomplished by aid of touch without sight, than is ordinarily
achieved. By these means, what at first requires consideration and care
(neither of which is accounted for by physiological explanations), comes
at last to be done without deliberation, and with so much facility, that
it does not seem to engage much attention. Physiological science thus
accounts for a considerable amount of superior activity characteristic
of man in his daily engagements. It must, however, be noticed that the
explanation is not a complete one, inasmuch as the action of the sensory
and motor apparatus referred to, presupposes consideration and care,
that is intellectual and voluntary guidance commensurate with the
initial difficulties of attainment, in order that the nerve system may
be brought to accomplish what becomes possible afterwards by mere
mechanical and chemical contrivance within the living organism.
Having thus briefly indicated the advances in knowledge of the working
of our own organism gained by recent research, and the explanation thus
afforded of much of the superiority manifest in human life, we come upon
the grand difficulty of science,--How to account for _intellectual
superiority_. It is obvious that animals give proofs of intelligence as
well as men; and that the human brain has a marked superiority in the
frontal region, to which intelligence is commonly referred, as it
certainly is superior also in the back part of the organ, to which
intelligence is not so commonly referred. But the pressing difficulty is
this, to show how nerve cells, confessedly concerned with the
development of nerve energy, and the production of sensory and motor
activity, can be further considered capable of performing the function
of thought, covering the whole variety of mental occupations. Attention
has been directed to the recognized diversities of nerve cells, which
are unipolar, bipolar, and multipolar, on the hypothesis that these
diversities may point to differences of function so great as to provide
what is required. But there is a total failure of evidence to
substantiate this hypothesis. The differences among the nerve cells of
the brain are differences in size, and in the number of the lines of
communication taking rise from them. In accordance with the plan of
arrangement everywhere recognized, the number of protoplasmic lines
originating from a cell gives an index to the points of contact it has
in the surrounding tissue, and thus to the part it may perform in the
work of coördination or interaction. A small cell with only a single
line or fibre proceeding from it, must be regarded as a cell conveying
nerve stimulus in only a single direction, and to only a single
destination. A bipolar cell in accordance with the same rule of
interpretation, is a cell having communication in two opposite
directions, and thus may be capable of transmitting stimulus by the one
channel or by the other, besides which it is possible, so far as
structure is concerned, that such a cell may receive stimulus from one
direction and send it forth in an opposite, thus proving a centre of
intercommunication. On the same plan, a multipolar cell, being of
greater size, and having from five to ten fibres proceeding from it,
holds a more important place in the manifold ramifications of cellular
tissue, sending out stimulus in an increased variety of courses
according to the number of the lines pertaining to it, and proving thus
an intermediate station in communication with a variety of distinct
centres. No observation yet directed upon the nerve cells has proved
sufficient to establish all this, but the supposition is in strict
harmony with what has been ascertained as to the laws governing the
action of the nerve system.
When, however, an attempt is made to proceed farther, selecting the
largest cells as "mind cells,"[CX] or cells generating thought and
volition, there is a complete break away from evidence, and from the
clear lines of interpretation already established. We are dealing with
conjecture, not with science. There is no reason in the interests of
truth to object to hypothesis in this region, any more than in another,
for conjecture has often proved the handmaid of discovery, and it is
likely to be so in a still larger degree. But an essential condition of
this acknowledgment is, that conjecture do not claim any respect beyond
what its nature warrants, and specially do not take to itself the name
of science,--knowledge, or certainty. Beyond this, it must be recognized
in every intelligent circle, that conjectures, like men of different
character, are entitled to different degrees of respect, some to only a
moderate and guarded measure, others to a very high degree, and some to
very little indeed. In a case like the present, we can have no sure test
for a provisional judgment entitled to regulate provisional procedure,
other than the harmony of the conjecture with scientific knowledge
already acquired as to the same region of existence. Judged by this
test, the conjecture that the intellectual life of man is to be
accounted for by the presence in the brain of myriads of thought cells,
volitional cells, memory cells, imagination cells, and emotional cells,
has little on which to claim a high degree of consideration. Its most
obvious scientific difficulties are these two, that it implies a
departure from the scheme of brain action scientifically established,
and that it passes away from the scientific appliances employed to
obtain knowledge of brain action. The real discoveries which have been
made are the existence of sensory and motor apparatus, and the
interaction of these two branches or divisions of the system. Beyond
this, science has made no advance. The scientific appliances by which
these discoveries have been reached are those available in post-mortem
dissection, and in experiment under such exposure of the brain tissue as
has been found compatible with functional activity of the organ. This
conjecture of "mind-cells" does not either experimentally or logically
connect itself with the recent advances in knowledge of the brain. The
system of sensory and motor apparatus spread over the body for which the
brain is the great central and governing organ does not under the
scientific explanation of it already obtained, lead on by natural
sequence to the conjecture of additional and greatly higher functions
being assigned to the brain. Besides, the suggestion that place should
be found in the brain for something more and higher than sensori-motor
activity, does not come from any necessity which has arisen in the
course of scientific observation. It is only because we know, in a
manner quite different from that in which scientific knowledge of nerve
and brain has been acquired, that man does observe, and reason,
construct hypotheses and cherish expectations, contemplate rules of
conduct and regulate his actions in accordance with them, that
scientific inquirers, attempting to include the whole range of human
powers, have felt themselves urged forward to seek an explanation of the
characteristics of mental life which are the familiar facts of man's
experience. The course of _experiment_ has not brought them up to these
facts; common acquaintance with them has pressed on scientific inquirers
the need for dealing with them in order to make good the claim that
science contains the explanation of all existence, man included. The
dilemma for this conjecture that the brain thinks and wills is serious.
If the brain is capable of what is commonly named _mental_ activity, all
that science has demonstrated is susceptibility and motor activity, that
is nerve impulse involving molecular and muscular action, and this
carries no explanation of mental action.
In this, as in previous cases, it is better to take purely scientific
statements concerning the structure and functions of the nerve cells,
without regard to theoretical result. The following quotations will show
what account has been given of the variety of appearance and position of
the nerve cells. Professor Turner says, nerve cells are "the
characteristic structures in the nerve centres, are susceptible to
impressions or nervous impulses, and are the texture in which the
molecular changes occur that produce or disengage the special form of
energy named nerve energy, the evolution of which is the distinctive
mark of a nerve centre."[CY] "The central extremities of the nerve
fibres lie in relation to, and are often directly connected with the
nerve cells." From opposite points of the surface of the _bipolar cell_
"a strong process is given off, which is directly continued into a nerve
fibre.[CZ]" When we pass next to _multipolar cells_, we have the
following explanations. "In many localities they present characteristic
forms. In the gray matter of the _spinal cord_, more especially in its
anterior horn,[DA] they give rise to numerous processes, and have a
stellate or radiate form. In the gray matter on the surface of the
convolutions of the cerebrum they are pyramidal in shape; the apex is
directed to the surface of the convolution, the base towards the white
matter; the processes arise from the base, apex, and sides of the
pyramid."[DB] "The processes which arise from a multipolar nerve cell as
a rule divide and subdivide as they pass away from the body of the cell,
until at last they give rise to branches of extreme tenuity. These
branching processes apparently consist exclusively of cell protoplasm,
and have been called protoplasm processes. Gerlach has described the
protoplasm processes of the multipolar nerve cells of the brain and
spinal cord as forming an excessively minute net-work, from which
minute medullated _nerve fibres_ arise."[DC] "From the observations of
Lockhart Clark, Arndt, Cleland and Meynert, there can be no doubt that
the pyramidal nerve cells vary in relative size and in numbers in the
different layers of the gray cortex, and that the largest sized
pyramidal cells lie in the third and fourth layers."[DD] "Large
pyramidal cells are found in the _frontal lobe_ in considerable
numbers," but it is added, "there is no difficulty in recognizing in the
occipital lobe" (the back region of the brain) "a small proportion of
cells quite equal in magnitude to the largest cells of the frontal
lobe."[DE]
From these statements, it is easy to judge what value can be attached to
the conjecture that multipolar or pyramidal cells are to be regarded as
"_mind-cells_." The result may be summarized thus; (1) The larger cells
are invariably distinguished by the number of fibres given off, or the
lines of communication they have with other parts of the tissue; (2) As
to distribution of these cell-fibres appearing in the brain, it is found
that as the cells themselves are in the lower strata of the gray matter,
the majority of their fibres stretch downwards, the mass of the nerve
fibres thus communicating with the organism; (3) These pyramidal cells
are not peculiar to any part of the brain, and they do not belong to the
brain alone, but are found in the gray matter of the spinal cord, and
also of the sympathetic system, which provides for the action of the
heart, lungs, and other vital organs. All these characteristics are
adverse to the conjecture that for the larger sized cells a claim can be
made assigning to them distinctively intellectual or mental functions.
In contrast with this view, I shall here introduce an extract from
Hæckel's _Evolution of Man_, as he may be accounted the most advanced
advocate of the theory of "mind-cells." He says,--"The nerve cell of the
brain is an extremely one-sided formation. It can not, like the
egg-cell, develop from itself numerous generations of cells, of which
some transform themselves into skin-cells, some into flesh-cells, and
others into bone-cells, etc. But instead, the nerve-cell, which is
formed for the highest activities of life, possesses the capacity to
feel, to will, to think. It is a true mind-cell, an elementary organ of
mental activity. Correspondingly, it has an extremely complex minute
structure. Innumerable filaments of exceeding fineness, which may be
compared to the numerous electric wires of a great central telegraph
station, traverse (crossing each other again and again), the finely
granulated protoplasm of the nerve-cell, and pass into branched
processes, which proceed from this mind-cell, and connect with other
nerve-cells and nerve-fibres. It is scarcely possible to trace, even
approximately, the tangled paths of these filaments in the fine
substance of the protoplasmic body. We thus, have before us a highly
complex apparatus, the more minute structure of which we have hardly
begun to know, even with the help of our strongest microscope, and the
significance of which we rather guess than know. Its complex mechanism
is capable of the most intricate physical functions. But even this
elementary organ of mental activity, of which there are thousands in our
brain, is only a single cell. Our whole intellectual life is but the sum
of the results of all such nerve-cells, or mind-cells."[DF]
From this passage it will be seen that ascertained facts are given in
harmony with previous descriptions; but that while naming some as
sensory, others as motor, there is no distinct evidence for classifying
certain cells as "mind-cells." Along with the admission of our
comparative ignorance of the minute structure of the cell, is the
assertion that this cell "possesses the capacity to feel, to will, to
think." This latter statement is advanced without any trace of
scientific evidence, and has no better substratum on which to rest than
the admission that man not only feels, but also thinks and wills.
Further, when we recall the singular variety of situation in which these
cells are found, as they lie within the spinal canal, subordinate
centres, and the brain, the insufficiency of the whole theory of
"mind-cells" is apparent. Still more conspicuous does this become when
we turn to Hæckel's illustrative diagram, and read underneath it this
description,--"A large branched nerve-cell, or 'mind-cell' from the
brain of an electric fish." The investigator who makes in the directest
manner statements as to thinking and willing, which he has not verified
and can not verify; and who with undisturbed composure of mind proceeds
to illustrate and support his position by giving a drawing of the
"mind-cell of an electric fish," does almost every thing that can be
done to discredit his testimony on scientific subjects.
Having now set forth the grounds on which I think it clearly shown that
physiological science has done no more than identify sensory and motor
cells; and that the search for the true "mind-cell" has proved a
failure; I pass from this division of the subject with the
acknowledgment that the front and back portions of the brain still
present area for fresh research, and to this must be added the striking
fact that in all the brains subjected to electric excitation these two
portions have uniformly remained silent. These considerations may
possibly hereafter afford valuable suggestions towards guidance of the
work yet to be done in the investigation of brain structure and
functions.