How We Think Part 7

[Sidenote: Thinking comes between observations at the beginning and at the end]

Observation exists at the beginning and again at the end of the process: at the beginning, to determine more definitely and precisely the nature of the difficulty to be dealt with; at the end, to test the value of some hypothetically entertained conclusion. Between those two termini of observation, we find the more distinctively _mental_ aspects of the entire thought-cycle: (_i_) inference, the suggestion of an explanation or solution; and (_ii_) reasoning, the development of the bearings and implications of the suggestion. Reasoning requires some experimental observation to confirm it, while experiment can be economically and fruitfully conducted only on the basis of an idea that has been tentatively developed by reasoning.

[Sidenote: The trained mind one that judges the extent of each step advisable in a given situation]

The disciplined, or logically trained, mind--the aim of the educative process--is the mind able to judge how far each of these steps needs to be carried in any particular situation. No cast-iron rules can be laid down. Each case has to be dealt with as it arises, on the basis of its importance and of the context in which it occurs. To take too much pains in one case is as foolish--as illogical--as to take too little in another. At one extreme, almost any conclusion that insures prompt and unified action may be better than any long delayed conclusion; while at the other, decision may have to be postponed for a long period--perhaps for a lifetime. The trained mind is the one that best grasps the degree of observation, forming of ideas, reasoning, and experimental testing required in any special case, and that profits the most, in future thinking, by mistakes made in the past. What is important is that the mind should be sensitive to problems and skilled in methods of attack and solution.

CHAPTER SEVEN

SYSTEMATIC INFERENCE: INDUCTION AND DEDUCTION

-- 1. _The Double Movement of Reflection_

[Sidenote: Back and forth between facts and meanings]

The characteristic outcome of thinking we saw to be the organization of facts and conditions which, just as they stand, are isolated, fragmentary, and discrepant, the organization being effected through the introduction of connecting links, or middle terms. The facts as they stand are the data, the raw material of reflection; their lack of coherence perplexes and stimulates to reflection. There follows the suggestion of some meaning which, _if_ it can be substantiated, will give a whole in which various fragmentary and seemingly incompatible data find their proper place. The meaning suggested supplies a mental platform, an intellectual point of view, from which to note and define the data more carefully, to seek for additional observations, and to inst.i.tute, experimentally, changed conditions.

[Sidenote: Inductive and deductive]

There is thus a double movement in all reflection: a movement from the given partial and confused data to a suggested comprehensive (or inclusive) entire situation; and back from this suggested whole--which as suggested is a _meaning_, an idea--to the particular facts, so as to connect these with one another and with additional facts to which the suggestion has directed attention. Roughly speaking, the first of these movements is inductive; the second deductive. A complete act of thought involves both--it involves, that is, a fruitful interaction of observed (or recollected) particular considerations and of inclusive and far-reaching (general) meanings.

[Sidenote: Hurry _versus_ caution]

This double movement _to_ and _from_ a meaning may occur, however, in a casual, uncritical way, or in a cautious and regulated manner. To think means, in any case, to bridge a gap in experience, to bind together facts or deeds otherwise isolated. But we may make only a hurried jump from one consideration to another, allowing our aversion to mental disquietude to override the gaps; or, we may insist upon noting the road traveled in making connections. We may, in short, accept readily any suggestion that seems plausible; or we may hunt out additional factors, new difficulties, to see whether the suggested conclusion really ends the matter. The latter method involves definite formulation of the connecting links; the statement of a principle, or, in logical phrase, the use of a universal. If we thus formulate the whole situation, the original data are transformed into premises of reasoning; the final belief is a logical or _rational_ conclusion, not a mere _de facto_ termination.

[Sidenote: Continuity of relationship the mark of the latter]

The importance of _connections binding isolated items into a coherent single whole_ is embodied in all the phrases that denote the relation of premises and conclusions to each other. (1) The premises are called grounds, foundations, bases, and are said to underlie, uphold, support the conclusion. (2) We "descend" from the premises to the conclusion, and "ascend" or "mount" in the opposite direction--as a river may be continuously traced from source to sea or vice versa. So the conclusion springs, flows, or is drawn from its premises. (3) The conclusion--as the word itself implies--closes, shuts in, locks up together the various factors stated in the premises. We say that the premises "contain" the conclusion, and that the conclusion "contains" the premises, thereby marking our sense of the inclusive and comprehensive unity in which the elements of reasoning are bound tightly together.[15] Systematic inference, in short, means the _recognition of definite relations of interdependence between considerations previously unorganized and disconnected, this recognition being brought about by the discovery and insertion of new facts and properties_.

[15] See Vailati, _Journal of Philosophy, Psychology, and Scientific Methods_, Vol. V, No. 12.

[Sidenote: Scientific induction and deduction]

This more systematic thinking is, however, like the cruder forms in its double movement, the movement _toward_ the suggestion or hypothesis and the movement _back_ to facts. The difference is in the greater conscious care with which each phase of the process is performed. _The conditions under which suggestions are allowed to spring up and develop are regulated._ Hasty acceptance of any idea that is plausible, that seems to solve the difficulty, is changed into a conditional acceptance pending further inquiry. The idea is accepted as a _working hypothesis_, as something to guide investigation and bring to light new facts, not as a final conclusion. When pains are taken to make each aspect of the movement as accurate as possible, the movement toward building up the idea is known as _inductive discovery_ (_induction_, for short); the movement toward developing, applying, and testing, as _deductive proof_ (_deduction_, for short).

[Sidenote: Particular and universal]

While induction moves from fragmentary details (or particulars) to a connected view of a situation (universal), deduction begins with the latter and works back again to particulars, connecting them and binding them together. The inductive movement is toward _discovery_ of a binding principle; the deductive toward its _testing_--confirming, refuting, modifying it on the basis of its capacity to interpret isolated details into a unified experience. So far as we conduct each of these processes in the light of the other, we get valid discovery or verified critical thinking.

[Sidenote: Ill.u.s.tration from everyday experience]

A commonplace ill.u.s.tration may enforce the points of this formula. A man who has left his rooms in order finds them upon his return in a state of confusion, articles being scattered at random. Automatically, the notion comes to his mind that burglary would account for the disorder. He has not seen the burglars; their presence is not a fact of observation, but is a thought, an idea. Moreover, the man has no special burglars in mind; it is the _relation_, the meaning of burglary--something general--that comes to mind. The state of his room is perceived and is particular, definite,--exactly as it is; burglars are inferred, and have a general status. The state of the room is a _fact_, certain and speaking for itself; the presence of burglars is a possible _meaning_ which may explain the facts.

[Sidenote: of induction,]

So far there is an inductive tendency, suggested by particular and present facts. In the same inductive way, it occurs to him that his children are mischievous, and that they may have thrown the things about. This rival hypothesis (or conditional principle of explanation) prevents him from dogmatically accepting the first suggestion. Judgment is held in suspense and a positive conclusion postponed.

[Sidenote: of deduction]

Then deductive movement begins. Further observations, recollections, reasonings are conducted on the basis of a development of the ideas suggested: _if_ burglars were responsible, such and such things would have happened; articles of value would be missing. Here the man is going from a general principle or relation to special features that accompany it, to particulars,--not back, however, merely to the original particulars (which would be fruitless or take him in a circle), but to new details, the actual discovery or nondiscovery of which will test the principle. The man turns to a box of valuables; some things are gone; some, however, are still there. Perhaps he has himself removed the missing articles, but has forgotten it. His experiment is not a decisive test. He thinks of the silver in the sideboard--the children would not have taken that nor would he absent-mindedly have changed its place. He looks; all the solid ware is gone. The conception of burglars is confirmed; examination of windows and doors shows that they have been tampered with. Belief culminates; the original isolated facts have been woven into a coherent fabric. The idea first suggested (inductively) has been employed to reason out hypothetically certain additional particulars not yet experienced, that _ought_ to be there, if the suggestion is correct. Then new acts of observation have shown that the particulars theoretically called for are present, and by this process the hypothesis is strengthened, corroborated. This moving back and forth between the observed facts and the conditional idea is kept up till a coherent experience of an object is subst.i.tuted for the experience of conflicting details--or else the whole matter is given up as a bad job.

[Sidenote: Science is the same operations carefully performed]

Sciences exemplify similar att.i.tudes and operations, but with a higher degree of elaboration of the instruments of caution, exactness and thoroughness. This greater elaboration brings about specialization, an accurate marking off of various types of problems from one another, and a corresponding segregation and cla.s.sification of the materials of experience a.s.sociated with each type of problem. We shall devote the remainder of this chapter to a consideration of the devices by which the discovery, the development, and the testing of meanings are scientifically carried on.

-- 2. _Guidance of the Inductive Movement_

[Sidenote: Guidance is indirect]

Control of the formation of suggestion is necessarily _indirect_, not direct; imperfect, not perfect. Just because all discovery, all apprehension involving thought of the new, goes from the known, the present, to the unknown and absent, no rules can be stated that will guarantee correct inference. Just what is suggested to a person in a given situation depends upon his native const.i.tution (his originality, his genius), temperament, the prevalent direction of his interests, his early environment, the general tenor of his past experiences, his special training, the things that have recently occupied him continuously or vividly, and so on; to some extent even upon an accidental conjunction of present circ.u.mstances. These matters, so far as they lie in the past or in external conditions, clearly escape regulation. A suggestion simply does or does not occur; this or that suggestion just happens, occurs, springs up. If, however, prior experience and training have developed an att.i.tude of patience in a condition of doubt, a capacity for suspended judgment, and a liking for inquiry, _indirect_ control of the course of suggestions is possible.

The individual may return upon, revise, restate, enlarge, and a.n.a.lyze _the facts out of which suggestion springs_. Inductive methods, in the technical sense, all have to do with regulating the conditions under which _observation, memory, and the acceptance of the testimony of others_ (_the operations supplying the raw data_) proceed.

[Sidenote: Method of indirect regulation]

Given the facts _A B C D_ on one side and certain individual habits on the other, suggestion occurs automatically. But if the facts _A B C D_ are carefully looked into and thereby resolved into the facts _A' B'' R S_, a suggestion will automatically present itself different from that called up by the facts in their first form. To inventory the facts, to describe exactly and minutely their respective traits, to magnify artificially those that are obscure and feeble, to reduce artificially those that are so conspicuous and glaring as to be distracting,--these are ways of modifying the facts that exercise suggestive force, and thereby indirectly guiding the formation of suggested inferences.

[Sidenote: Ill.u.s.tration from diagnosis]

Consider, for example, how a physician makes his diagnosis--his inductive interpretation. If he is scientifically trained, he suspends--postpones--reaching a conclusion in order that he may not be led by superficial occurrences into a snap judgment. Certain conspicuous phenomena may forcibly suggest typhoid, but he avoids a conclusion, or even any strong preference for this or that conclusion until he has greatly (_i_) _enlarged_ the scope of his data, and (_ii_) rendered them more _minute_. He not only questions the patient as to his feelings and as to his acts prior to the disease, but by various manipulations with his hands (and with instruments made for the purpose) brings to light a large number of facts of which the patient is quite unaware. The state of temperature, respiration, and heart-action is accurately noted, and their fluctuations from time to time are exactly recorded. Until this examination has worked _out_ toward a wider collection and _in_ toward a minuter scrutiny of details, inference is deferred.

[Sidenote: Summary: definition of scientific induction]

Scientific induction means, in short, _all the processes by which the observing and ama.s.sing of data are regulated with a view to facilitating the formation of explanatory conceptions and theories_. These devices are all directed toward selecting the precise facts to which weight and significance shall attach in forming suggestions or ideas. Specifically, this selective determination involves devices of (1) elimination by a.n.a.lysis of what is likely to be misleading and irrelevant, (2) emphasis of the important by collection and comparison of cases, (3) deliberate construction of data by experimental variation.

[Sidenote: Elimination of irrelevant meanings]

(1) It is a common saying that one must learn to discriminate between observed facts and judgments based upon them. Taken literally, such advice cannot be carried out; in every observed thing there is--if the thing have any meaning at all--some consolidation of meaning with what is sensibly and physically present, such that, if this were entirely excluded, what is left would have no sense. A says: "I saw my brother."

The term _brother_, however, involves a relation that cannot be sensibly or physically observed; it is inferential in status. If A contents himself with saying, "I saw a man," the factor of cla.s.sification, of intellectual reference, is less complex, but still exists. If, as a last resort, A were to say, "Anyway, I saw a colored object," some relationship, though more rudimentary and undefined, still subsists.

Theoretically, it is possible that no object was there, only an unusual mode of nerve stimulation. None the less, the advice to discriminate what is observed from what is inferred is sound practical advice. Its working import is that one should eliminate or exclude _those_ inferences as to which experience has shown that there is greatest liability to error. This, of course, is a relative matter. Under ordinary circ.u.mstances no reasonable doubt would attach to the observation, "I see my brother"; it would be pedantic and silly to resolve this recognition back into a more elementary form. Under other circ.u.mstances it might be a perfectly genuine question as to whether A saw even a colored _thing_, or whether the color was due to a stimulation of the sensory optical apparatus (like "seeing stars" upon a blow) or to a disordered circulation. In general, the scientific man is one who knows that he is likely to be hurried to a conclusion, and that part of this precipitancy is due to certain habits which tend to make him "read" certain meanings into the situation that confronts him, so that he must be on the lookout against errors arising from his interests, habits, and current preconceptions.

[Sidenote: The technique of conclusion]

The technique of scientific inquiry thus consists in various processes that tend to exclude over-hasty "reading in" of meanings; devices that aim to give a purely "objective" unbiased rendering of the data to be interpreted. Flushed cheeks usually mean heightened temperature; paleness means lowered temperature. The clinical thermometer records automatically the actual temperature and hence checks up the habitual a.s.sociations that might lead to error in a given case. All the instrumentalities of observation--the various -meters and -graphs and -scopes--fill a part of their scientific role in helping to eliminate meanings supplied because of habit, prejudice, the strong momentary preoccupation of excitement and antic.i.p.ation, and by the vogue of existing theories. Photographs, phonographs, kymographs, actinographs, seismographs, plethysmographs, and the like, moreover, give records that are permanent, so that they can be employed by different persons, and by the same person in different states of mind, _i.e._ under the influence of varying expectations and dominant beliefs. Thus purely personal prepossessions (due to habit, to desire, to after-effects of recent experience) may be largely eliminated. In ordinary language, the facts are _objectively_, rather than _subjectively_, determined. In this way tendencies to premature interpretation are held in check.

[Sidenote: Collection of instances]

(2) Another important method of control consists in the multiplication of cases or instances. If I doubt whether a certain handful gives a fair sample, or representative, for purposes of judging value, of a whole carload of grain, I take a number of handfuls from various parts of the car and compare them. If they agree in quality, well and good; if they disagree, we try to get enough samples so that when they are thoroughly mixed the result will be a fair basis for an evaluation. This ill.u.s.tration represents roughly the value of that aspect of scientific control in induction which insists upon multiplying observations instead of basing the conclusion upon one or a few cases.

[Sidenote: This method not the whole of induction]

So prominent, indeed, is this aspect of inductive method that it is frequently treated as the whole of induction. It is supposed that all inductive inference is based upon collecting and comparing a number of like cases. But in fact such comparison and collection is a secondary development within the process of securing a correct conclusion in some single case. If a man infers from a single sample of grain as to the grade of wheat of the car as a whole, it is induction and, under certain circ.u.mstances, a _sound_ induction; other cases are resorted to simply for the sake of rendering that induction more guarded, and more probably correct. In like fashion, the reasoning that led up to the burglary idea in the instance already cited (p. 83) was inductive, though there was but one single case examined. The particulars upon which the general meaning (or relation) of burglary was grounded were simply the sum total of the unlike items and qualities that made up the one case examined.

Had this case presented very great obscurities and difficulties, recourse might _then_ have been had to examination of a number of similar cases. But this comparison would not make inductive a process which was not previously of that character; it would only render induction more wary and adequate. _The object of bringing into consideration a mult.i.tude of cases is to facilitate the selection of the evidential or significant features upon which to base inference in some single case._

[Sidenote: Contrast as important as likeness]