THE PROBLEM OF SOUL AND BODY
§ 1. The problem of psychophysical connection has to do with the
correlation of scientific abstractions, not of given facts of
experience. § 2. The “consciousness” of Psychology is thus not the
same thing as the finite individual subject of experience, and
Reality must not be said to consist of “minds” in the psychologist’s
sense. Again, we must not assume _a priori_ that there can be only
_one_ working hypothesis of psychophysical connection. § 3. The
possible hypotheses may be reduced to three, Epiphenomenalism,
Parallelism, and Interaction. § 4. _Epiphenomenalism_ is legitimate
as a methodological principle in Physiology; it is untenable as a
basis for Psychology because it implies the reduction of psychical
facts to mechanical law. § 5. _Parallelism._ The arguments for
Parallelism as necessarily valid to Psychophysics because of its
congruity with the postulates of mechanical Physics, are fallacious.
We cannot assume that Psychology must necessarily conform to these
postulates. § 6. As a working hypothesis Parallelism is available
for many purposes, but breaks down when we attempt to apply it to
the case of the initiation of fresh purposive reactions. A
teleological and a mechanical series cannot ultimately be
“parallel.” § 7. We are thus thrown back on the hypothesis of
_Interaction_ as the only one which affords a consistent scheme for
the correlation of Physiology and Psychology. We have, however, to
remember that what the hypothesis correlates is scientific symbols,
not actual facts. The actuality represented by both sets of symbols
is the same thing, though the psychological symbolism affords a
wider and more adequate representation of it than the physiological.
§ 1. Few questions have more constantly attracted the attention of
philosophers, especially perhaps of those philosophers who have lived
since the establishment of Christianity as the religion of the Western
world, than that of the relation between the soul or mind and the body;
and perhaps no question has given rise to graver misconceptions for want
of a correct insight into the true logical character of the problem
under discussion. Both in the half-scientific speculations of ordinary
persons and in the more systematic theories of metaphysicians and
psychologists, the subject is constantly approached under the totally
erroneous preconception that the dualistic separation of human life into
a bodily and a mental part or aspect is a datum of immediate experience
which we can directly verify in ourselves, and that the task of
philosophy is by ingenious but unverifiable hypothesis to transcend this
chasm between given realities. From the standpoint of our previous
chapter we can easily see that such a view fundamentally misrepresents
the real philosophical problem.
So long as we are concerned with human existence as we directly find it
in our immediate experience, or assume it in our practical social
relations with our fellows, no question of the relation between body and
mind can arise, because neither term of the relation is as yet before
us. For my own immediate experience I am neither a body nor a soul, nor
yet a composite of the two, but simply an individual subject of
experiences in direct intercommunion with other individuals. Under the
influence of conscious or unconscious dualistic prepossessions, we often
speak as if it were a directly experienced fact that I can communicate
with my fellow-subjects only indirectly through the medium of an alien
“material” body, and we sometimes contrast this supposed restriction
with an imagined higher state of existence, in which “disembodied
spirits” may conceivably have direct intercourse with each other. But
the truth is, that this direct intercourse and influence of one
intelligent and purposive individual on another is no privilege reserved
for our enjoyment in “a better world than this”; it is, as we can see if
we will only forget our dualistic prepossessions, the very truth about
our actual life. In actual life, before we have contaminated our direct
enjoyment of it with psychological prejudices, we know nothing of the
interposition of an inert “material” organisation between ourselves and
the members of our social environment. The severance of the original
unity of experience into a physical and a psychical aspect is entirely a
product of our own abstraction-making intellect. “Body” and “soul” are
not given actualities of experience, but artificial mental constructions
of our own derived from the actual “facts” of life by the elaborate
processes which we have just been studying.
As we have seen in constructing our concept of a mechanical physical
order, we abstract certain elements of our direct experience from the
whole, and consider them under the name of our “bodies” as if they had a
separate existence; we then, by the aid of the hypothesis of
“introjection,” represent those elements of direct self-experience which
were omitted from the physical order as forming by themselves a second
distinct whole or system called the “soul.” When we have reached this
point, we are, of course, compelled to raise the question how these two
systems, the bodily and the mental, must be supposed to be connected.
But the important fact to remember is that the two systems are not facts
of experience, but products of abstraction. Our task in discussing their
relation is not to transcend a _given_ dualism, but to get rid of one
which we have manufactured for ourselves by the manipulation of
experience in the interests of certain special scientific problems.
Hence, as Münsterberg well puts it, we have not to _find the_ connection
which subsists, as an actual fact, between body and soul, but to _invent
a_ connection in keeping with the general scheme of our artificial
physical and psychological hypotheses.[174]
§ 2. As far as the interests of Metaphysics are concerned, this
recognition that the problem of soul and body has to do solely with
highly artificial products of scientific abstraction, and not with
anything which can be called a “given” actuality, is the one principle
of supreme importance which emerges from the discussion of the subject.
Two very significant inferences may at once be drawn from it. (1) We
clearly must not call the finite subjects of experience, of whom we saw
reason to hold that ultimate Reality is exclusively constituted, “minds”
or “souls” in the psychologist’s sense.[175] To call them so would
inevitably be to imply that exclusion from the physical order of
“bodies” apart from which the psychological concept of the “soul” or
“mind” has no significance. Or, in other words, it would identify them
not with what they are for their own direct experience, but with what
they become for one another’s theoretical reflection under the influence
of “introjection.” As we have seen, it is legitimate and necessary for
special scientific purposes to treat ourselves and other individuals _as
if_ we were such series of “mental states,” but it is never legitimate
to forget that, when we do this, we are substituting a highly unreal
symbolism for directly experienced facts.
One consequence of confusing the symbolism with the fact may be noted in
passing: when we have substituted the series of mental states for the
felt unity of actual conscious life, we go on to ask ourselves how the
fact and its symbol—the symbolic nature of which we have forgotten—are
related. And thus arise all the unanswerable, because fundamentally
unmeaning, questions as to the way in which the “self” _has_ or _owns_
the succession of “states.” Failing to see that the succession of states
is simply the unitary subject itself, as it appears from the point of
view of the “introjection” hypothesis, we then find ourselves confronted
by the alternatives of foisting upon our Psychology the useless and
unthinkable fiction of a changeless “substratum” of mental states—the
soul-substance of the pre-Kantian psychologists—or resolving real life
into a succession of discontinuous “mental images.” With the recognition
that Psychology never deals directly with experienced reality, but
always with the hypothetical products of an abstraction which is only
justified by its usefulness for the special purposes of the
psychologist, all these difficulties disappear.
(2) Another important consequence of our principle is that we cannot
dogmatically assert that there can be only _one_ legitimate theory of
the “connection between mind and body.” If “mind” and “body” were really
given as distinct but connected in direct experience, it might well be
that there could only be one account of their connection answering to
experienced fact. But since the separation is itself of our own
intellectual manufacture, as we are dealing throughout with artificial
creations of our own abstraction, any theory of their connection which
is desirable for the solution of a special problem or class of problems
will be legitimate _for that particular class of problems_. Thus the
physiologist may legitimately, if it answers his special purposes, adopt
a working hypothesis which the psychologist may find untenable, and
again different types of psychological problem may legitimately assume
different working hypotheses.[176] I shall aim at showing in the
immediately following paragraphs that there is one typical
psychophysical hypothesis which, on the whole, lends itself better than
its rivals to the general purposes of both Physiology and Psychology,
but we shall see, as we proceed, that the hypotheses we reject are also
legitimate for the solution of important special problems. In fact, our
chief interest, as students of Metaphysics, in the further discussion of
psychophysical connection will be to point out the fallaciousness of the
metaphysical arguments which are commonly used to establish some one
hypothesis as necessarily and exclusively true.
§ 3. Turning now to consider the chief types of hypothesis which have
been, or are at present, actually put forward by metaphysicians and
psychologists, we may perhaps group them under the five main heads of
(1) Pre-established Harmony, (2) Occasionalism, (3) Epiphenomenalism,
(4) Psychophysical Parallelism, (5) Interaction. For our purpose in the
present chapter the number of alternatives may be further reduced by the
omission of the first two. Neither the Pre-established Harmony of
Leibnitz nor the Occasionalism advocated by Geulincx and Malebranche,
and in a one-sided form by Berkeley, is likely to find much support from
the philosophy of the present day. Both doctrines are, moreover,—that of
Leibnitz avowedly and that of the Occasionalists by implication,—much
more than special psychophysical hypotheses. They are in principle
attempts to get rid of all transeunt causality, and have been discussed
in their general bearings in our chapter on the Causal Postulate, where
we satisfied ourselves that any science which recognises, as Psychology
has to do, the existence of finite things must also admit the principle
of transeunt causality, at any rate as a working hypothesis.
Each of the three remaining types of view has its supporters among
contemporary students of science and philosophy. The epiphenomenalist
theory is largely adopted by the workers in the physical sciences, and
though not much countenanced by psychologists and metaphysicians, has
the explicit support of Dr. Shadworth Hodgson, while some versions of
the parallelist doctrine, notably that of Münsterberg, approach it very
closely. The parallelist hypothesis is perhaps at present the most
popular among the psychological specialists, and is represented by
writers of such eminence as Wundt, Münsterberg, Ebbinghaus, Höffding and
Stout. Finally, Interaction has powerful champions in Bradley, Ward, and
James; to say nothing of its adoption by so sound a physiologist as Mr.
McDougall. Both the latter doctrines, again, have historical connections
with the great philosophical systems of the past, Parallelism with that
of Spinoza, and Interaction with those, to mention no other names, of
Descartes and Locke. In the philosophy of the ancient world the
psychophysical issue can hardly be said to appear in a well-defined
form, but we may perhaps state that Plato’s psychological doctrine is
decidedly one of Interaction, while the view of Aristotle, though too
complex to admit of very precise formulation, inclines rather towards
Parallelism.
§ 4. _Epiphenomenalism._ Of the three hypotheses which remain for
discussion, the theory of Epiphenomenalism has the least to recommend
it, and is open to the most serious objections. According to this view,
all causal connections are exclusively between physical states. Bodily
changes succeed one another in accord with uniform laws of sequence,
which it is the province of the physiologist to discover, and every
bodily change is completely determined by bodily antecedents. Certain
bodily conditions are further attended by corresponding “states of
consciousness,” but those states stand in no causal connection with
subsequent bodily states, nor yet with one another. They are thus
consequences or effects, but are never causes. The whole series of
physical changes, from birth to death, which makes up the history of the
human body, goes on precisely as it would if “consciousness” were
entirely absent. This is what is meant by the assertion that all mental
states are _epi_phenomena, superfluous accessories, which arise in the
course of the connected series of bodily changes, but are entirely
without any determining influence upon it. The doctrine may be
diagrammatically represented thus
_a_——α
|╭──╮
_b_——β
|╭──╮
_c_——γ,
where the italic letters symbolise physical and the Greek letters
psychical states, the vertical lines indicating the course of causal
sequence.
If a psychophysical hypothesis were ever directly applicable to the
actualities of experience, we might, of course, dismiss Epiphenomenalism
at once as inherently absurd. For nothing is more certain than that in
the actual life of direct experience our knowledge and our interests do
determine the course of our actions. That what we believe and desire
does make all the difference in the world to the way in which we behave,
is one of those elementary verities out of which no scientific
hypothesis can claim to reason us. Hence, when the defenders of the
theory attempt to draw practical moral and juristic consequences from
their doctrines, we are within our rights in simply declining to concern
ourselves with so absurd a travesty of the simplest facts of experience.
So long, however, as the hypothesis is put forward simply as a working
hypothesis for the correlation of our physiological and psychological
theories, the case is different. Its validity as a psychophysical theory
must be estimated solely by the degree in which it renders this
systematic correlation feasible, and is not necessarily impaired by the
manifest absurdities which result from mistaking the doctrine for a
description of actual life.
Now, if we look at the hypothesis from this point of view, we can at
once see that it is really legitimate for some purposes. For the purpose
of physiological science it is obviously to our interest that we should
be able to deduce the later from the earlier stages of a physiological
process. We have thus an interest in treating physiological changes, if
we can, as unconditioned by any but physiological antecedents. And every
actual success in establishing a uniformity or “law” of Cerebral
Physiology is proof that the assumption that, for the process in
question, the only determining conditions which count are physiological,
is equivalent to the truth. The physiologist, then, is clearly justified
in treating the psychical series as epiphenomenal, if he means no more
by this than that he intends to deal, as a physiologist, only with
processes which can be successfully resolved into uniform sequences on
the assumption that they involve only physiological terms. Though
whether any processes in the nervous system can be successfully treated
as purely physiological sequences, nothing but the physiologist’s actual
success in obtaining results from his initial postulate can decide.
If, however, the physiologist should go on, as he sometimes does, to
make the assertion that not only can some nervous processes be treated
_as if_ their psychical accompaniments made no difference, but that they
really are what they would be without those accompaniments, or even that
_all_ nervous process is what it would be without “consciousness,” he
commits a gross logical fallacy. It is a mere blunder in logic to argue
that because the presence of certain circumstances makes no difference
to the special result which follows on a given antecedent, the result
would equally follow in their absence. For it might be that in their
removal the very antecedents in which we are interested would disappear.
We are not at liberty to infer that, because the course of certain
physiological processes can be computed without taking their mental
correlates into account, they could occur apart from those correlates.
Even more serious are the consequences which follow when it is assumed
that _all_ mental processes without exception may be regarded as
epiphenomenal, _i.e._ that all human action, if only our Physiology were
sufficiently advanced, might be brought under laws of purely
physiological sequence. Such an assumption would lead at once to the
following dilemma: Either our Physiology must remain rigidly faithful to
the fundamental postulates of mechanical science, or not. If it is
faithful to them, its descriptions of human action must rigidly exclude
all reference to teleological determination by reference to conceived
and desired ends. _I.e._ we must treat human conduct as if it were
fatally determined apart from any possible influence of human choice and
intention, and thus stultify that whole work of historical and ethical
appreciation which we have already seen to be the principal _raison
d’être_ of Psychology as a science. We must revert, in fact, to a theory
of life which is identical with the extremest forms of Pagan or
Mohammedan fatalism in everything except the name it gives to its
_ineluctabile fatum._ Or, if we are not prepared to do this, we must
allow Physiology itself to use the psychological categories of desire,
selection, and choice, and thus covertly admit that human action, after
all, cannot be described without the introduction of factors not
included in the physical order. It is no doubt due to their realisation
of this dilemma that psychologists are all but universally agreed to
reject the epiphenomenalist hypothesis, while its popularity with
physiologists may be explained by observing that physiological
uniformities can manifestly only be successfully established for those
processes which can be treated _as if_ they were only physiologically
conditioned.
§ 5. _Parallelism._ The hypothesis of Parallelism attempts, while
preserving some of the characteristic features of the cruder view just
described, to avoid its unsatisfactory consequences. Agreeing with
Epiphenomenalism in the doctrine that physiological changes must be
treated as determined only by physiological antecedents, Parallelism
denies that the events of the psychical series are mere “secondary”
effects of their physiological correlates. According to it, the series
of physical and that of psychical events are strictly “parallel,” but
not causally connected. Each event in either series has its precise
counterpart in the other, but the physical events do not cause the
psychical events, nor _vice versâ_. The successive members of the
physical series form a connected causal sequence, independent of their
psychical concomitants, while these latter, it is generally
assumed,[177] form a similar chain of causally connected psychical
states. Thus every nervous change is determined solely by precedent
nervous changes, and the corresponding psychical change by the
corresponding antecedent psychical changes. In diagrammatic shape our
hypothesis now takes the form
╭──╮
_a_ α
| |
_b_ β
| |
_c_ γ
Usually it is further added that the ultimate metaphysical explanation
of this parallelism without mutual dependence must be found in the
(Spinozistic) doctrine of _Identity_, _i.e._ the doctrine that the
physical and psychical series are two different “sides” or “aspects” of
a single reality. Some supporters of Parallelism (_e.g._, Ebbinghaus)
conceive this single reality as a _tertium quid_, equally adequately
expressed by both the series, others (_e.g._, Stout) hold that its real
nature is more adequately revealed in the mental than in the physical
series.
The grounds commonly adduced in favour of the parallelistic view as the
most satisfactory psychophysical theory, are of two kinds. As a positive
argument it is urged that cerebral anatomy has already to some extent
confirmed the doctrine of correspondence between definite physical and
psychical processes by its successful “localisation” of specific sensory
and motor processes in various cortical “centres,” and may reasonably be
expected to accomplish further such “localisations” in the future.
Stress is also laid upon the formal analogy between the psychological
laws of retentiveness, association, and habit, and the physiological
theories of the formation of “conduction-paths” in the brain. These
positive contentions do not, however, take us far. The correspondences
upon which they rest, so far as they are ascertained experimentally and
are not mere deductions from the principle of Parallelism itself, would
be equally natural on a theory of Interaction, or of one-sided
dependence of either series on the other. The real strength of the case
for Parallelism rests upon certain negative assumptions which are widely
believed to exclude the hypothesis of causal dependence of either series
on the other. These negative assumptions appear to be in the main three.
(1) It is said that, while we can without difficulty conceive how the
later stages of a continuous physical or psychical process can be
connected by causal law with its earlier stages, we are entirely unable
to conceive how psychical events can arise from physical antecedents, or
_vice versâ_, because of the utter disparateness of the physical and the
psychical. The physical process, it is urged, is continuous, and so, on
the other side, is the psychical, but when we attempt to think of a
cerebral change conditioning a mental change, or _vice versâ_, there is
a complete solution of continuity which we cannot bridge by any causal
formula.
(2) The doctrine of Conservation of Energy is sometimes supposed to be
incompatible with the admission of psychical states among the
antecedents or consequents of physical states. It is said that if
psychical states can influence the course of nervous change, there will
be “work” done in the organism without the expenditure of energy, and if
the total effect of nervous change is not exclusively physical there
will be loss of energy without “work” being done by the organism, and in
either case the principle of Conservation will be contravened.
(3) Finally, it is maintained that it is a fundamental postulate of the
physical sciences, that every change of configuration in a material
system such as the living organism is assumed to be, is due to
exclusively physical antecedents, and that this postulate must therefore
be respected in Psychophysics. These are, so far as I can gather them
from the works of the psychologists who adopt the parallelist view, the
principal arguments by which their case is supported.
It is clear that if all—or any—of these contentions are valid, it must
follow that Parallelism is not only a legitimate but the only legitimate
hypothesis for the co-ordination of physical and psychical science. I
believe, however, that every one of them is fallacious, and that for the
following reasons:—
(1) The argument from the inconceivability of causal relation between
the physical and the psychical is perhaps the most effective of the
alleged grounds for denying interaction between the psychical and the
physical. Yet its force is not really so great as it might appear. It is
not denied that we can, in simple cases, assign the conditions under
which a mental state follows on a physical state (_e.g._, we can assign
the physical conditions of the emergence of a given sensation). But, it
is argued, we cannot show why those conditions (_e.g._, the stimulation
of the retina, and indirectly of the “optical centres” in the brain by
light of a given wave length) should be followed by this particular
sensation (_e.g._, green, and not some other colour). This means that we
cannot construct a mathematical equation connecting the character of the
sensation with that of the stimulus, as we can to connect the earlier
with the later stages of a purely physical process. This is, of course,
obvious enough. It is only by making complete abstraction from the
appearance of new _qualities_ in the course of a process, and by
treating it as a purely geometrical and quantitative transformation,
that we can render it amenable to our equations.
As we saw in our discussion of Causality, mathematical Physics only
succeeds in its constructions on the condition of excluding all
_qualitative_ change, as “subjective,” from its purview. But we also saw
there that the origination of the qualitatively new is an essential part
of the idea of Causality, and that in reducing all change in the
physical world to quantitative transformation, mathematical Physics
really does away with the causal concept. We are, in fact, in precisely
the same logical position if we speak of physiological changes as
_causing_ sensation, as when we speak of a quantitative change in the
proportions of a chemical compound as the _cause_ of alteration in its
qualities. The objection that the psychical effect cannot be connected
by an equation with its alleged cause, would hold equally in any case of
the production of the qualitatively new, _i.e._ in every case where we
use the category of causality at all. And for that very reason it has no
force when urged as an objection to psychophysical causality in
particular.[178]
(2) The argument from the Conservation of Energy may be more briefly
dismissed, as its fallacious character has been fully recognised by the
ablest recent exponents of the parallelistic view, such as Dr. Stout and
Professor Münsterberg. As Dr. Stout points out, the argument involves a
formal _petitio principii_. The principle of Conservation of Energy has
only been established for what are technically known as conservative
material systems, and no absolute proof has been given, or seems likely
to be given, that the human organism is such a conservative system.
Further, as has been urged by many critics, and notably by Professor
Ward, the principle of conservation, taken by itself, is simply a law of
exchanges. It asserts that the _quantity_ of the energy of a
conservative system remains constant under all the transformations
through which it passes, but, apart from the rest of the postulates of
mechanical science, it affords no means of deciding _what_
transformations of energy shall occur in the system, or _when_ they
shall occur. Hence there would be no breach with the special principle
of Conservation of Energy if we were to assume that psychical conditions
can determine the moment at which energy in the organism is transformed
_e.g._, from the kinetic to the potential state, without affecting its
quantity.
(3) It is, however, true that it is inconsistent with the postulates of
mechanical Physics, taken as a whole, to admit the determination of
physical sequences by non-physical conditions. To admit such
determination would be to stultify the whole procedure of the mechanical
sciences. For, as we have seen in our Third Book, the primary object of
mechanical science is to reduce the course of events to rigid laws of
uniform sequence, and thus to facilitate the formulation of practical
rules for our own interference with it. It is therefore a legitimate
postulate of mechanical science that—for its special object—desire and
will shall be excluded from our conception of the conditions which
determine events, and the whole course of nature treated _as if_
conditioned only by physical antecedents. If there is any department of
experienced reality which cannot be successfully dealt with according to
these postulates, then the formulation of rigid laws of uniform sequence
is, in principle, impossible for that department, and it must be
excluded from the “world” which mechanical science investigates.
But the fact that mechanical science can only attain its end by treating
all physical events as independent of non-physical conditions, does not
afford the slightest presumption that they must be treated in the same
way for all purposes and by every branch of inquiry. Whether Psychology,
in particular, is under the logical necessity of conforming to the
mechanical postulates, will depend upon our view as to whether the
object subserved by Psychology is the same as that of the mechanical
sciences, or different. If our purpose in psychological investigation is
not identical with the purposes of mechanical science, there is no sense
in demanding that we shall hamper our procedure as psychologists by
adherence to postulates based upon the special nature of the interests
to which mechanical science has to minister.
Now, we have already contended that the aims of Psychology only
partially and temporarily coincide with those of the mechanical
sciences. If we were right in holding that the principal object of
Psychology is to provide a general terminology of which History and
Ethics can avail themselves in their appreciations of life, it follows
at once that Psychology imperatively needs the recognition of that very
teleological aspect of human action which is excluded on principle, and
rightly so for the special purpose of mechanical Physics, by the
fundamental mechanical postulates. Thus the argument that the
parallelistic hypothesis must be the most suitable for the psychologist,
because it conforms to the mechanical postulates of sciences which deal
with experience from a different standpoint and in a different interest,
loses all its cogency.[179]
Now that we have, as I trust, sufficiently disposed of the _a priori_
arguments for the parallelistic view, we are in a position to estimate
it, as a psychological hypothesis, purely on its merits as evinced by
its actual success. But first we must point out once more that the whole
question is not one as to actualities, but purely as to the most
satisfactory way of bringing two sets of abstractions, originally
devised for divergent purposes, into touch with one another; and
further, that _if_ the hypothesis were put forward as a final
metaphysical truth about the constitution of the real world, it would be
manifestly self-contradictory.
In the first place, Parallelism, taken for anything more than a
convenient working hypothesis, would involve a flagrant breach of logic.
It is obvious that, as Mr. Bradley has urged, you cannot infer from the
premisses that one total state, containing both a physical and a
psychical element, causes another complex state of the same kind, the
conclusion that the physical aspect of the first, by itself, has caused
the physical, and the psychical the psychical aspect of the second. To
get this conclusion you need a “negative instance,” in which either the
physical or the psychical state is found apart from its correlate, but
followed by the same consequent as before, and Parallelism itself denies
the possibility of such an instance. From the premisses that _a_ α is
always followed by _b_ β, it attempts to infer, without any “dissection
of nature,” that _a_ by itself was the necessary and sufficient
condition of _b_, and α of β. And this is, of course, logically
fallacious. Dr. Ward expresses the same point differently when he urges
that unvarying and precise concomitance _without_ causal connection is a
logical absurdity.
That the supporters of the hypothesis themselves are conscious of the
difficulty, is shown by their unanimous assertion that the psychical and
physical series are ultimately manifestations of one and the same
reality. What they do not explain is how, if this is so, the two series
can be phenomenally so utterly disparate as to exclude mutual influence
on one another. The difficulty becomes insuperable when we reflect that
on the parallelistic view the physical series must be rigidly
mechanical, as otherwise we shall have a breach with those mechanical
postulates which are supposed to require the exclusion of psychical
states from the determining conditions of physical occurrences. Thus, if
teleology is to be recognised anywhere in our scientific constructions,
it must be in our conception of the psychical series. And on the whole
the supporters of Parallelism admit this in practice by the free use of
teleological categories in their Psychology. But it ought by now to be
clear to us that the nature of the identical reality cannot be expressed
with equal adequacy in a teleological series, and in one which is, by
the principles of its construction, purely mechanical. Here, again, most
of the parallelists are really in agreement with us, for they usually in
the end call themselves “Idealists,” and assert that the “mental” series
is a more faithful representation of Reality than the physical. But if
the two series are not on the same level in respect of their nearness to
Reality, it is hard to see how there can be exact correspondence between
them. This is a point to which we shall immediately have to return.[180]
§ 6. When we ask, however, whether Parallelism, apart from these
questions of ultimate philosophy, is legitimate _as a working hypothesis
in Psychology_, the answer must be that, in certain departments of
psychological investigation, it certainly is so. In practice, the
doctrine of the parallel but independent series amounts, for the most
part, to little more than a methodological device for the division of
labour between the physiologist and the psychologist, the physiologist
restricting himself to the formulation of such uniformities as can be
established between nervous processes, considered as if independent of
external influence, and the psychologist doing the same for their
psychical accompaniments. As a principle of methodical procedure,
therefore, in those parts of Psychology which deal with the more passive
and, as we may say, routine-like aspects of mental life, Parallelism is
a useful and therefore a legitimate working hypothesis.
The question by which its claim to be the _best_ hypothesis must be
decided is, to my mind, that of its applicability to the case of the
fresh initiation of new purposive adaptations to changes in the
organism’s environment.[181] For it is just in dealing with these cases
that Psychology, if it is to fulfil the purpose we have ascribed to it,
must most obviously discard mechanical for teleological categories.
Hence it is here, if anywhere, that a difficulty of principle must make
itself felt when we attempt to treat the psychical and the physical
series as exactly parallel and corresponding. It seems to follow
necessarily from the conception of physical science as based upon the
mechanical postulate, that a teleological and a mechanical series cannot
possibly run “parallel” in all their details in the fashion presupposed
by the hypothesis under consideration.
If Psychology is to be of any use in supplying Ethics and History with
the subject-matter of their appreciations, it is manifest that it must
make the assumption that desire and choice are operative in determining
the course of human action, and thus must—at certain points at
least—explicitly employ the categories of teleology. These categories,
again, cannot possibly be translated into the rigidly non-teleological
symbolism of a physical science, based upon the mechanical postulates,
as every science of “general laws” must be. It follows that “exact
parallelism _without_ mutual interference” cannot, consistently with the
purpose which Psychology subserves, be employed, even as a working
hypothesis throughout the whole field of psychological investigation
itself. When the attempt to extend its employment to the whole sphere of
psychical processes is seriously made, it leads inevitably to the crude
fatalism of the doctrine that there is no such thing as choice or action
(free or otherwise) in the universe. In actual practice, the supporters
of Parallelism, who reject this doctrine when it is explicitly avowed
under the name of Epiphenomenalism, only succeed in doing so because
they do not really insist on carrying out the parallelistic hypothesis
in their Psychology. They commonly make their hypothesis prominent,
while they are dealing with the comparatively passive and routine-like
aspects of mental life, association, habituation, etc., but allow
themselves to lose sight of it as soon as they come to treat of such
explicitly teleological concepts as attention and choice. Their
procedure is also rendered easier for them by the liberal use which
evolutionary biologists, even while professing with their lips fidelity
to the mechanical postulates, allow themselves to make of teleological
categories which are really purely psychological.
It would be an easy task, if space permitted, to show in detail how the
fundamentally different principles underlying the construction of the
mechanical and the teleological series involve the presence, in the
individual members of each series, of characters to which nothing
corresponds in those of the other. Thus we might ask, with Dr. Ward,
what corresponds in the psychical scheme to the composition of the units
of the physiological scheme out of their various chemical components,
and of these, again, out of more elementary physical “prime atoms”?[182]
or, from the opposite side, we might ask, what is the cerebral
equivalent, in terms of a rigidly mechanical Physiology, of the
psychological character of “meaning” or “significance”? But the
multiplication of these problems becomes superfluous if the reader has
once grasped our principle, that exact correspondence is only possible
between series which are either both mechanical or both—and both in the
same degree—teleological. Between a genuinely teleological and an
honestly mechanical series such correspondence is logically impossible,
because of the fundamental difference between their types of
construction.
§ 7. For the reasons just produced, it is, I think, necessary to hold
that the oldest and simplest hypothesis of the connection between body
and mind, that of _Interaction_, is after all the most satisfactory.
According to this view, the two series cannot be thought of as
presenting an exact correspondence, and must be thought of as causally
influencing each other at different points, precisely as any two sets of
physical events do. If we adopt it we shall recognise in sensation a
psychical state which has physical processes among its immediate
antecedents, and in motor reaction similarly a physical process with
psychical antecedents. It is scarcely to be denied that this conception
of body and mind, as two things which stand in causal relation, is the
hypothesis which most naturally presents itself, when once we have
artificially broken up the unity of immediate experience into a physical
and a psychical side, and so created the problem of psychophysical
connection. So natural is it, that even psychologists who accept one of
the other hypotheses are to be found constantly speaking of voluntary
movement in terms which, if they mean anything, imply causal
determination of bodily by mental process, while no psychologist of any
school has ever succeeded in expressing the relation of sensation to
stimulus in any other phraseology than that of Interaction. Probably the
hypothesis would never have been exposed to hostile criticism at all,
but for the metaphysical objections, already dismissed by us as
fallacious, founded upon the notion that the mechanical postulates with
which Interaction conflicts are ascertained truths about the actual
structure of the reality with which we are in touch in immediate
experience.
It is clear that, from the nature of the problem to be solved, we cannot
be called upon to _prove_ the actual occurrence of psychophysical
interaction. As a working hypothesis for the interrelation of two sets
of scientific abstractions, the theory is in principle incapable of
direct establishment by the “appeal to facts.” All that is requisite for
its justification is to show that it is (_a_) not in principle at
variance with any fundamental axiom of scientific procedure, and (_b_)
enables us to co-ordinate our scientific results in the manner most
suitable for the uses to which we propose to put them. Both these
conditions are fulfilled by the hypothesis of Interaction, if our
foregoing arguments are sound. We have seen the fallacious nature of the
objections brought against it on _a priori_ grounds of logical method,
and have also seen that it is positively demanded if we are at once to
be faithful to the mechanical postulates upon which physical science
depends for its successes, and to recognise in our psychological
constructions that teleological character of human action which is
all-essential for History and Ethics. In substance this is the whole
case for the Interaction hypothesis, and no further accession of
strength would result from its elaboration in detail.
It may be added that it is one great recommendation of the hypothesis of
Interaction, that it is quite consistent with the full recognition of
the relative usefulness of the alternative theories, though they, as we
have seen, are unable to do justice to those aspects of fact which can
only be expressed in terms of Interaction. Thus the hypothesis of
Interaction can readily afford to admit that, for certain purposes and
up to a certain point, it is possible to treat physical or psychical
processes _as if_ they were determined solely by physical or psychical
conditions respectively, and even to treat some physical processes _as
if_ the presence of their psychical concomitants made no difference at
all to their occurrence. The reason of this is, that whereas a
mechanical hypothesis can give no intelligible account of a purposive
process at all, a teleological hypothesis can quite easily account for
the apparently mechanical character of some of the processes which fall
under it. As we have seen (Book III. chap. 3, § 6), a purposive
reaction, once established, approximates to mechanical uniformity in the
regularity with which it continues to be repeated, while the conditions
are unchanged, and the end of the reaction is therefore still secured by
its repetition.
Thus we can readily see that, even if we contented ourselves with the
attempt to translate into the language of psychological science the
processes which make up the life of an individual subject, many of them
would appear to be going on with routine uniformity. And when we
deliberately set ourselves to obtain uniformities by taking an average
result, derived from comparison of a multitude of subjects, our results
are, of course, always mechanical in appearance, because the element of
individual purpose and initiative has been excluded by ourselves from
our data in the very process of taking the average. Hence we can
understand how, on the hypothesis of Interaction itself, all those
mental processes which consist in the repetition of an already
established type of reaction should come to appear mechanical, and thus
to suggest that mechanical conception of psychical processes which is
common to the epiphenomenalist and the parallelist view. Interaction,
and Interaction alone, is thus a hypothesis capable of being applied to
the _whole_ field of psychological investigation.
I will conclude this chapter with some considerations on the bearing of
our result upon the special problems of Metaphysics. We have explicitly
defended Interaction as being no statement of actual experienced fact,
but a working hypothesis for the convenient correlation of two
scientific constructions, neither of which directly corresponds to the
actualities of experience. This means, of course, that Interaction
cannot possibly be the final truth for Metaphysics. It cannot ultimately
be the “fact” that “mind” and “body” are things which react upon each
other, because, as we have seen, neither “mind” nor “body” is an actual
datum of experience; for direct experience and its social relations, the
duality subsequently created by the construction of a physical order
simply has no existence. Nor can it be maintained that this duality,
though not directly given as a datum, is a concept which has to be
assumed in order to make experience consistent with itself, and is
therefore the truth. For the concept of Interaction manifestly reposes
upon the logically prior conception of the physical as a rigidly
mechanical system. It is because we have first constructed the notion of
the “body” on rigidly mechanical lines that we have subsequently to
devise the concept of “mind” or “soul” as a means of recognising and
symbolising in our science the non-mechanical character of actual human
life. And since we have already seen that the mechanical, as such,
cannot be real, this whole scheme of a mechanical and a non-mechanical
system in causal relation with one another can only be an imperfect
substitute for the Reality it is intended to symbolise. In fact, we
might have drawn the same conclusion from the very fact that the
psychophysical hypothesis we have adopted is couched in terms of
Transeunt Causality, since we have already satisfied ourselves that all
forms of the causal postulate are more or less defective appearance.
The proposition that the psychophysical theory of the “connection” of
“body” and “mind” is an artificial transformation, due to the needs of
empirical science, of the actual teleological unity of human experience,
is sometimes expressed by the statement that mind and body are really
one and the same thing. In its insistence upon the absence of the
psychophysical duality from actual experience, this saying is correct
enough, but it perhaps fails to express the truth with sufficient
precision. For, as it stands, the saying conveys no hint of the very
different levels on which the two concepts stand in respect to the
degree of truth with which they reproduce the purposive teleological
character of real human experience. It would perhaps be nearer the mark
to say that, while the physiologist’s object, the “body,” and the
psychologist’s object, the “mind,” are alike conceptual symbols,
substituted, from special causes, for the single subject of actual life,
and may both be therefore said to “mean” or “stand for” the same thing,
their actual content is different. For what in the language of
physiology I call my “body” includes only those processes of actual life
which approximate to the mechanical ideal sufficiently closely to be
capable of being successfully treated as merely mechanical, and
therefore brought under a scheme of general “laws” of nature. Whereas
what, as a psychologist, I call my “mind” or “soul,” though it includes
processes of an approximately mechanical type, includes them only as
subordinate to the initiation of fresh individual reactions against
environment which can only be adequately expressed by teleological
categories. Thus, though “mind” and “body” in a sense mean the same
actual thing, the one stands for a fuller and clearer view of its true
nature than the other. In Dr. Stout’s terminology their _intent_ may be
the same, but their content is different.[183]
_Consult further_:—R. Avenarius, _Der Menschliche Weltbegriff_; B.
Bosanquet, _Psychology of the Moral Self_, lect. 10; F. H. Bradley,
_Appearance and Reality_, chap. 23; Shadworth Hodgson, _Metaphysic of
Experience_, vol. ii. pp. 276-403; William James, _Principles of
Psychology_, vol. i. chaps. 5 and 6; H. Lotze, _Metaphysic_, bk. iii.
chaps. 1 and 5 (Eng. trans., vol. ii. pp. 163-198, 283-517); H.
Münsterberg, _Grundzüge der Psychologie_, i. chaps. 11. (pp. 402-436),
15 (pp. 525-562); G. F. Stout, _Manual of Psychology_,^3 Introduction,
chap. 3; James Ward, _Naturalism and Agnosticism_, vol. ii. lects. 11
and 12 (art. “Psychology” in Supplement to _Encyclopædia Britannica_, p.
66 ff.).
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Footnote 174:
Compare the following striking passage from Avenarius, _Menschliche
Weltbegriff_, p. 75: “Let an individual _M_ denote a definite whole of
‘perceived things’ (trunk, arms and hands, legs and feet, speech,
movements, etc.) and of ‘presented thoughts’ as _I_, ... then when _M_
says ‘_I_ have a brain,’ this means that a brain belongs as part to
the whole of perceived things and presented thoughts denoted as _I_.
And when _M_ says ‘_I_ have thoughts,’ this means that the thoughts
themselves belong as a part to the whole of perceived things and
presented thoughts denoted as _I_. But though thorough analysis of the
denotation of _I_ thus leads to the result that we _have_ a brain and
thought, it never leads to the result that the _brain has_ the
thoughts. The thought is, no doubt, a thought of ‘my Ego,’ but not a
thought of ‘my brain’ any more than my brain is the brain of ‘my
thought.’ _I.e._ the brain is no habitation, seat, generator,
instrument or organ, no support or substratum of _thought_. Thought is
no indweller or commander, no other half or side, and also no product,
indeed not even a physiological function or so much as a state of the
_brain_.”
Footnote 175:
As elsewhere in this work, I am using the terms “mind” and “soul” as
virtually interchangeable names for the object studied by the
psychologist. So far as there is any definite distinction of meaning
between the terms as currently used by English writers, “soul” seems
to carry with it more of the implication of substantiality and
relative independence than “mind.” It might not be amiss to adopt the
term “soul” as a name for the finite subject of experience as he is
for himself in actual social life, and to confine the name “mind” to
the construction which symbolises this subject for psychological
purposes. But the popular antithesis between soul and body is perhaps
too strongly rooted to admit of this suggestion. In earlier passages,
_e.g._, Book II. chap. 2, § 6, I have used the term “spirit” in the
sense here suggested for “soul.”
Footnote 176:
So, in dealing with astronomical problems, we are free to adopt either
the Copernican or the Ptolemaic scheme, whichever happens to be the
more _convenient_ for our special purpose. The superior _truth_ of the
Copernican system seems to mean no more than that the range of its
utility is the wider of the two. I may observe that I do not here
employ the term “utility” in the narrowly practical sense of those
philosophers who, _e.g._, condemn all speculation about the “Absolute”
on the ground of inutility. Whatever satisfies _any_ human aspiration
is for me, so far, “useful.” It follows that there is, for me, no such
thing as the “useless knowledge” which “Pragmatism” denounces. Thus,
if a man’s peace of mind depends upon speculation about the
“Absolute”—on the habits of angels, or any other topic you like (and
this is a matter in which every man must in the end decide for
himself)—Pragmatism would appear to be false to its own principle in
forbidding him to speculate.
Footnote 177:
The assumption is not always made, however. Professor Münsterberg, who
classes himself as a supporter of Parallelism, holds on metaphysical
grounds that all causal connection must be between physical states.
Hence he denies that psychical states can be causally connected with
one another, except indirectly through the causal relations of their
physical correlates. His doctrine is thus hardly to be distinguished
from Epiphenomenalism, except in terminology, though he avoids the
consequence of practical Fatalism by his insistence upon the purely
artificial nature of both the physical and the psychical series. (His
reason for refusing to admit causal relation between psychical states
is that causal connection can only be established between universals,
whereas every psychical state is _unique_. Does not this argument
imply a confusion between the actual experience and its psychological
symbol?)
Footnote 178:
Most supporters of Parallelism, it may be noted, stultify their own
case, so far as it rests on this special contention, by admitting the
causal determination of psychical states by one another, though, as
psychical states are essentially qualitative, the reduction of
causation to quantitative identity is particularly inadmissible here.
Professor Münsterberg is quite consistent, therefore, in denying
psychical causality and reducing Parallelism to Epiphenomenalism.
Footnote 179:
The reader who has followed the argument of our Third Book will not
need to be reminded that the world of purely mechanical processes is
simply an ideal construction based on postulates which we make for
their practical convenience, and in no sense a direct transcript of
the world of actual experience.
Footnote 180:
The “neutral Monism” to which the doctrine of rigid Parallelism
logically leads, when put forward as more than a working hypothesis,
will, one may hope, in England at least, fail to survive the exposure
of its illogicalities in the second volume of Professor Ward’s
_Naturalism and Agnosticism_.
Footnote 181:
This case includes, as will be apparent on a little reflection, not
only the initiation of new motor reactions upon a sensation or
percept, but also that of sensation itself as a qualitatively novel
reaction upon physiological stimulation, and thus includes both the
processes in which supporters of Interaction have always recognised
the causal interconnection of the physical and the psychical.
Footnote 182:
It is with great pleasure that I note the coincidence of my own view
on the impossibility of reconciling Parallelism with the recognition
of the psychological importance of “meaning” with that of Mr. Gibson
(essay on “The Problem of Freedom,” in _Personal Idealism_, p. 150
ff.). Professor Münsterberg’s declaration, that the consciousness
investigated by Psychology “knows nothing by its knowledge and wills
nothing by its will,” seems to me a confession of the bankruptcy of
Parallelism as a basal psychological hypothesis. Still more so his
elaborate and brilliant demonstration that the “brain” with which my
“mind” may be regarded as “parallel” is not the brain as studied and
charted by the anatomist, _i.e._ not the brain as a physical object at
all. See _Psychologie_, i. 415-428.
Footnote 183:
See his essay on “Error” in _Personal Idealism_.
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