In the various discussions of the hypothesis which have appeared in
works on inductive logic and in writings on scientific method, its
structure and function have received considerable attention, while its
origin has been comparatively neglected. The hypothesis has generally
been treated as that part of scientific procedure which marks the stage
where a definite plan or method is proposed for dealing with new or
unexplained facts. It is regarded as an invention for the purpose of
explaining the given, as a definite conjecture which is to be tested by
an appeal to experience to see whether deductions made in accordance
with it will be found true in fact. The function of the hypothesis is to
unify, to furnish a method of dealing with things, and its structure
must be suitable to this end. It must be so formed that it will be
likely to prove valid, and writers have formulated various rules to be
followed in the formation of hypotheses. These rules state the main
requirements of a good hypothesis, and are intended to aid in a general
way by pointing out certain limits within which it must fall.
In respect to the origin of the hypothesis, writers have usually
contented themselves with pointing out the kind of situations in which
hypotheses are likely to appear. But after this has been done, after
favorable external conditions have been given, the rest must be left to
"genius," for hypotheses arise as "happy guesses," for which no rule or
law can be given. In fact, the genius differs from the ordinary plodding
mortal in just this ability to form fruitful hypotheses in the midst of
the same facts which to other less gifted individuals remain only so
many disconnected experiences.
This unequal stress which has been laid on the structure and function of
the hypothesis in comparison with its origin may be attributed to three
reasons: (1) The facts, or data, which constitute the working material
of hypotheses are regarded as given to all alike, and all alike are more
or less interested in systematizing and unifying experience. The purpose
of the hypothesis and the opportunity for forming it are thus
practically the same for all, and hence certain definite rules can be
laid down which will apply to all cases where hypotheses are to be
employed. (2) But beyond this there seems to be no clue that can be
formulated. There is apparently a more or less open acceptance of the
final answer of the boy Zerah Colburn, who, when pressed to give an
explanation of his method of instantaneous calculation, exclaimed in
despair: "God put it into my head, and I can't put it into yours."[56]
(3) And, furthermore, there is very often a strong tendency to disregard
investigation into the origin of that which is taken as given, for,
since it is already present, its origin, whatever it may have been, can
have nothing to do with what it is now. The facts, the data, are _here_,
and must be dealt with as they _are_. Their past, their history or
development, is entirely irrelevant. So, even if we could trace the
hypothesis farther back on the psychological side, the investigation
would be useless, for the rules to which a good hypothesis must conform
would remain the same.
Whether or not it can be shown that Zerah Colburn's ultimate explanation
is needed in logic as little as Laplace asserted a similar one to be
required in his celestial mechanics, it may at least be possible to
defer it to some extent by means of a further psychological inquiry. It
will be found that psychological inquiry into the origin of the
hypothesis is not irrelevant in respect to an understanding of its
structure and function; for origin and function cannot be understood
apart from each other, and, since structure must be adapted to function,
it cannot be independent of origin. In fact, origin, structure, and
function are organically connected, and each loses its meaning when
absolutely separated from each other. It will be found, moreover, that
the data which are commonly taken as the given material are not
something to which the hypothesis is subsequently applied, but that,
instead of this external relation between data and hypothesis, the
hypothesis exercises a directive function in determining what are the
data. In a word, the main object of this discussion will be to contend
against making a merely convenient and special way of regarding the
hypothesis a full and adequate one. Though we speak of facts and of
hypotheses that may be applied to them, it must not be forgotten that
there are no facts which remain the same whatever hypothesis be applied
to them; and that there are no hypotheses which are hypotheses at all
except in reference to their function in dealing with our subject-matter
in such a way as to facilitate its factual apprehension. Data are
selected in order to be determined, and hypotheses are the ways in which
this determination is carried on. If, as we shall attempt to show, the
relation between data and hypothesis is not external, but strictly
correlative, it is evident that this fact must be taken into account in
questions concerning deduction and induction, analytic and synthetic
judgments, and the criterion of truth. Its bearing must be recognized in
the investigation of metaphysical problems as well, for reality cannot
be independent of the knowing process. In a word, the purpose of this
discussion of the hypothesis is to determine its nature a little more
precisely through an investigation of its rather obscure origin, and to
call attention to certain features of its function which have not
generally been accorded their due significance.
I
_The hypothesis as predicate._--It is generally admitted that the
function of the hypothesis is to provide a way of dealing with the data
or subject-matter which we need to organize. In this use of the
hypothesis it appears in the rôle of predicate in a judgment of which
the data, or facts, to be construed constitute the subject.
In his attempts to reduce the movements of the planets about the sun to
some general formula, Kepler finally hit upon the law since known as
Kepler's law, viz., that the squares of the periodic times of the
several planets are proportional to the cubes of their mean distances
from the sun. This law was first tentatively advanced as a hypothesis.
Kepler was not certain of its truth till it had proved its claim to
acceptance. Neither did Newton have at first any great degree of
assurance in regard to his law of gravitation, and was ready to give it
up when he failed in his first attempt to test it by observation of the
moon. And the same thing may be said about the caution of Darwin and
other investigators in regard to accepting hypotheses. The only reason
for their extreme care in not accepting at once their tentative
formulations or suggestions was the fear that some other explanation
might be the correct one. This rejection of other possibilities is the
negative side of the matter. We become confident that our hypothesis is
the right one as we lose confidence in other possible explanations; and
it might be added, without falling into a circle, that we lose
confidence in the other possibilities as we become more convinced of our
hypothesis.
It appears that such may be the relation of the positive and negative
sides in case of such elaborate hypotheses as those of Kepler and
Newton; but is it true where our hypotheses are more simple? It is not
easy to understand why the fact that the hypothesis is more simple, and
the time required for its formulation and test a good deal shorter,
should materially change the state of affairs. The question remains:
Why, if there is no opposition, should there be any uncertainty? In all
instances, then, the hypothesis appears as one among other possible
predicates which may be applied to our data taken as subject-matter of a
judgment.
_The predicate as hypothesis._--Suppose, then, the hypothesis is a
predicate; is the predicate necessarily a hypothesis? This is the next
question we are called upon to answer, and, since the predicate cannot
very well be taken aside from the judgment, our question involves the
nature of the judgment.
While it will not be necessary to give a very complete account of the
various definitions of the judgment that might be adduced, still the
mention of a few of the more prominent ones may serve to indicate that
something further is needed. In definitions of the judgment sometimes
the subjective side is emphasized, sometimes the objective side, and in
other instances there are attempts to combine the two. For instance,
Lotze regards the judgment as the idea of a unity or relation between
two concepts, with the further implication that this connection holds
true of the object referred to. J. S. Mill says that every proposition
either affirms or denies existence, coexistence, sequence, causation, or
resemblance. Trendelenburg regards the judgment as a form of thought
which corresponds to the real connection of things, while Ueberweg
states the case a little differently, and says that the essence of
judgment consists in recognizing the objective validity of a subjective
connection of ideas. Royce points to a process of imitation and holds
that in the judgment we try to portray by means of the ideas that enter
into it. Ideas are imitative in their nature. Sigwart's view of the
judgment is that in it we say something about something. With him the
judgment is a synthetic process, while Wundt considers its nature
analytic and holds that, instead of uniting, or combining, concepts into
a whole, it separates them out of a total idea or presentation. Instead
of blending parts into a whole, it separates the whole into its
constituent parts. Bradley and Bosanquet both hold that in the judgment
an ideal content comes into relation with reality. Bradley says that in
every judgment reality is qualified by an idea, which is symbolic. The
ideal content is recognized as such, and is referred to a reality beyond
the act. This is the essence of judgment. Bosanquet seems to perceive a
closer relation between idea and reality, for although he says that
judgment is the "intellectual function which defines reality by
significant ideas," he also tells us that "the subject is both in and
out of the judgment, as Reality is both in and out of my consciousness."
In all these definitions of judgment the predicate appears as ideal. An
ideal content is predicated of something, whether we regard this
something as an idea or as reality beyond, or as reality partly within
and partly without the act of judging; and it is ideal whether we
consider it as one of the three parts into which judgments are usually
divided, or whether we say, with Bosanquet and Bradley, that subject,
predicate, and copula all taken together form a single ideal content,
which is somehow applied to reality. Moreover, we not only judge about
reality, but it seems to be quite immaterial to reality whether we judge
concerning it or not.
Many of our judgments prove false. Not only do we err in our judgments,
but we often hesitate in making them for fear of being wrong; we feel
there are other possibilities, and our predication becomes tentative.
Here we have something very like the hypothesis, for our ideal content
shows itself to be a tentative attempt in the presence of alternatives
to qualify and systematize reality. It appears, then, on the basis of
the views of the judgment that have been mentioned, that not only do we
find the hypothesis taking its place as the predicate of a judgment, but
the predicate is itself essentially of the nature of a hypothesis.
In the views of the judgment so far brought out, reality, with which it
is generally admitted that the judgment attempts to deal in some way,
appears to lie outside the act of judging. Now, everyone would say that
we make some advance in judging, and that we have a better grasp of
things after than before. But how is this possible if reality lies
without or beyond our act of judging? Is the reality we now have the
same that we had to begin with? If so, then we have made no advance as
far as the real itself is concerned. If merely our conception of it has
changed, then it is not clear why we may not be even worse off than
before. If reality does lie beyond our judgment, then how, in the nature
of the case, can we ever know whether we have approached it or have gone
still farther away? To make any claim of approximation implies that we
do reach reality in some measure, at least, and, if so, it is difficult
to understand how it lies beyond, and is independent of, the act of
judging.
_Further analysis of judgment._--It remains to be seen whether a further
investigation of the judgment will still show the predicate to be a
hypothesis. It is evident that in some cases the judgment appears at the
end of a more or less pronounced reflective process, during which other
possible judgments have suggested themselves, but have been rejected.
The history of scientific discovery is filled with cases which
illustrate the nature of the process by which a new theory is developed.
For instance, in Darwin's _Formation of Vegetable Mould through the
Action of Earth Worms_, we find the record of successive steps in the
development of his hypothesis. Darwin suspected from his observations
that vegetable mold was due to some agency which was not yet determined.
He reasoned that if vegetable mold is the result of the life-habits of
earthworms, _i. e._, if earth is brought up by them from beneath the
surface and afterward spread out by wind and rain, then small objects
lying on the surface of the ground would tend to disappear gradually
below the surface. Facts seemed to support his theory, for layers of red
sand, pieces of chalk, and stones were found to have disappeared below
the surface in a greater or less degree. A common explanation had been
that heavy objects tend to sink in soft soil through their own weight,
but the earthworm hypothesis led to a more careful examination of the
data. It was found that the weight of the object and the softness of the
ground made no marked difference, for sand and light objects sank, and
the ground was not always soft. In general, it was shown that where
earthworms were found vegetable mold was also present, and _vice versa_.
In this investigation of Darwin's the conflicting explanations of
sinking stones appear within the main question of the formation of
vegetable mold by earthworms. The facts that disagreed with the old
theory about sinking stones were approached through this new one. But
the theories had something in common, viz., the disappearance of the
stones or other objects: they differed in their further determination of
this disappearance. In this case it may seem as if the facts which were
opposed to the current theory of sinking stones were seen to be
discrepant only after the earthworm hypothesis had been advanced; the
conflict between the new facts and the old theory appears to have
arisen through the influence of the new theory.
There are cases, however, where the facts seem clearly to contradict the
old theory and thus give rise to a new one. For example, we find in
Darwin's introduction to his _Origin of Species_ the following: "In
considering the origin of species it is quite conceivable that a
naturalist reflecting on the mental affinities of organic beings, on
their embryological relations, their geographical distribution,
geological succession, and other such facts, might come to the
conclusion that species had not been independently created but had
descended, like varieties, from other species." It would seem from this
statement that certain data were found for which the older theory of
independent creation did not offer an adequate explanation. And yet the
naturalist would hardly "reflect" on all these topics in a comparative
way unless some other mode of interpretation were already dawning upon
him, which led him to review the accepted reflections or views.
As a more simple illustration, we may cite the common experience of a
person who is uncertain concerning the identity of an approaching
object, say, another person. At first he may not be sure it is a person
at all. He then sees that it is someone, and as the person approaches he
is inclined to believe him to be an acquaintance. As the supposed
acquaintance continues to approach, the observer may distinguish certain
features that cause him to doubt, and then relinquish his supposition
that it is an acquaintance. Or, he may conclude at once that the
approaching person is another individual he knows, and the transition
may be so readily made from one to the other that it would be difficult
to determine whether the discordant features are discordant before the
new supposition arises, or whether they are not recognized as
conflicting till this second person is in mind. Or, again, the
identification of the new individual and the discovery of the features
that are in conflict with the first supposition may appear to go on
together.
Now, marked lines of likeness appear between this relatively simple
judgment and the far more involved ones of scientific research. In the
more extended scientific process we find data contradicting an old
theory and a new hypothesis arising to account for them. The hypothesis
is tested, and along with its verification we have the rejection, or
rather the modification, of the old theory. Similarly, in case of the
approaching stranger all these features are present, though in less
pronounced degree. In scientific investigation there is an interval of
testing by means of more careful consideration of the data and even
actual experimentation. Before an explanation is accepted subject to
test, a number of others may have been suggested and rejected. They may
not have received even explicit recognition. In case of the
identification of the stranger this feature is also present. Between two
fairly definite attempts to identify the mind does not remain a mere
blank or stationary, but other possible identifications may be suggested
which do not have sufficient plausibility to command serious attention;
they are only comparatively brief suggestions or tendencies.
It is to be noted that in all these instances the first supposition was
not _entirely_ abandoned, but was modified and more exactly determined.
(Why it could not be wholly false and the new one wholly new, will be
considered later in connection with discussion of the persistence and
re-formation of habit.) There was such a modification of the old theory
as would meet the requirements of the new data, and the new explanations
thus contained both old and new features.
We have seen that the predicate of the scientific judgment is a
hypothesis which is consciously applied to certain data. If the
similarity between the scientific judgment and the more immediate and
simple judgment is to be maintained, it is clear that the predicate of
the simple judgment must be of like nature. The structure of the two
varieties of judgment differs only in the degree of explicitness which
the hypothesis acquires. That is, the predicate of a judgment, as such,
is ideal; it is meaning, significant quality. If conditions are such as
to make the one judging hesitant or doubtful the mind wavers; the
predicate is not applied at once to the determination or qualification
of data, and hence comes to more distinct consciousness on its own
account. From being "ideal," it becomes _an_ idea. Yet its sole purpose
and value remains in its possible use to interpret data. Let the idea
remain detached, and let the query whether it be a true predicate
(_i. e_., really fit to be employed in determining the present data)
become more critical, and the idea becomes clearly a hypothesis.[57] In
other words, the hypothesis is just the predicate-function of judgment
definitely apprehended and regarded with reference to its nature and
adequacy.
_Psychological analysis of judgment._--This hypothetical nature of the
predicate will be even more apparent after a further psychological
analysis, which, while applying more directly to the simpler and more
immediate judgments, may be extended to the more involved ones as well.
In psychological terms, we may say, in explanation of the judging
process, that some stimulus to action has failed to function properly as
a stimulus, and that the activity which was going on has thus been
interrupted. Response in the accustomed way has failed. In such a case
there arises a division in experience into sensation content as subject
and ideal content as predicate. In other words, an activity has been
going on in accordance with established habits, but upon failure of the
accustomed stimulus to be longer an adequate stimulus this particular
activity ceases, and is resumed in an integral form only when a new
habit is set up to which the new or altered stimulus is adequate. It is
in this process of reconstruction that subject and predicate appear.
Sensory quality marks the point of stress, or seeming arrest, while the
ideal or imaged aspect defines the continuing activity as projected, and
hence that with which start is to be made in coping with the obstacle.
It serves as standpoint of regard and mode of indicated behavior. The
sensation stands for the interrupted habit, while the image stands for
the new habit, that is, the new way of dealing with the
subject-matter.[58]
It appears, then, that the purpose of the judgment is to obtain an
adequate stimulus in that, when stimulus and response are adjusted to
each other, activity will be resumed. But if this reconstruction and
response were to follow at once, would there be any clearly defined act
of judging at all? In such a case there would be no judgment, properly
speaking, and no occasion for it. There would be simply a ready
transition from one line of activity to another; we should have changed
our method of reaction easily and readily to meet the new requirements.
On the one hand, our subject-matter would not have become a clearly
recognized datum with which we must deal; on the other hand, there would
be no ideal method of construing it.[59] Activity would have changed
without interruption, and neither subject nor predicate would have
arisen.
In order that judgment may take place there must be interruption and
suspense. Under what conditions, then, is this suspense and uncertainty
possible? Our reply must be that we hesitate because of more or less
sharply defined alternatives; we are not sure which predicate, which
method of reaction, is the right one. The clearness with which these
alternatives come to mind depends upon the degree of explicitness of the
judgment, or, more exactly, the explicitness of the judgment depends
upon the sharpness of these alternatives. Alternatives may be carefully
weighed one against the other, as in deliberative judgments; or they may
be scarcely recognized as alternatives, as in the case in the greater
portion of our more simple judgments of daily conduct.
_The predicate is essentially hypothetical._--If we review in a brief
résumé the types of judgment we have considered, we find in the explicit
scientific judgment a fairly well-defined subject-matter which we seek
further to determine. Different suggestions present themselves with
varying degrees of plausibility. Some are passed by as soon as they
arise. Others gain a temporary recognition. Some are explicitly tested
with resulting acceptance or rejection. The acceptance of any one
explanation involves the rejection of some other explanation. During the
process of verification or test the newly advanced supposition is
recognized to be more or less doubtful. Besides the hypothesis which is
tentatively applied there is recognized the possibility of others. In
the disjunctive judgment these possible reactions are thought to be
limited to certain clearly defined alternatives, while in the less
explicit judgments they are not so clearly brought out. Throughout the
various forms of judgment, from the most complex and deliberate down to
the most simple and immediate, we found that a process could be traced
which was like in kind and varied only in degree. And, finally, in the
most immediate judgments where some of these features seem to disappear,
the same account not only appears to be the most reasonable one, but
there is the additional consideration, from the psychological side, that
were not the judgment of this doubtful, tentative character, it would be
difficult to understand how there could be judgment as distinct from a
reflex. It appears, then, that throughout, the predicate is essentially
of the nature of a hypothesis for dealing with the subject-matter. And,
however simple and immediate, or however involved and prolonged, the
judgment may be, it is to be regarded as essentially a process of
reconstruction which aims at the resumption of an interrupted
experience; and when experience has become itself a consciously
intellectual affair, at the restoration of a unified objective
situation.