The use of a good dictionary will be advantageous to the student in developing the power of Generalization or Conception. Starting with a species, he may build up to higher and still higher classes by consulting the dictionary; likewise, starting with a large class, he may work down to the several species composing it. An encyclopedia, of course, is still better for the purpose in many cases. Remember that Generalization is a prime requisite for clear, logical thinking. Moreover, it is a great developer of Thought.
JUDGMENT
We have seen that in the several mental processes which are grouped together under the general head of Understanding, the stage or step of Abstraction is first; following which is the second step or phase, called Generalization or Conception. The third step or phase is that which is called Judgment. In the exercise of the faculty of Judgment, we determine the agreement or disagreement between two concepts, ideas, or objects of thought, by comparing them one with another. From this process of comparison arises the Judgment, which is expressed in the shape of a logical Proposition. A certain form of Judgment must be used, however, in the actual formation of a Concept, for we must first compare qualities, and make a judgment thereon, in order to form a general idea. In this place, however, we shall confine ourselves to the consideration of the faculty of Judgment in thestrictly logical usage of the term, as previously stated.
We have seen that the expression of a concept is called a Term, which is thenameof the concept. In the same way when we compare two terms (expressions of concepts) and pass Judgment thereon, the expression of that Judgment is called a Proposition. In every Judgment and Proposition there must be two Terms or Concepts, connected by a little word "is" or "are," or some form of the verb "to be," in the present tense indicative. This connecting word is called the Copula. For instance, we may compare the two termshorseandanimal, as follows: "A horse is an animal," the wordisbeing the Copula or symbol of theaffirmativeJudgment, which connects the two terms. In the same way we may form anegativeJudgment as follows: "A horse is not a cow." In a Proposition,the term of which something is affirmedis called the Subject; andthe term expressing that which is affirmed of the subjectis called the Predicate.
Besides the distinction between affirmative Judgments, or Propositions, there is a distinction arising fromquantity, which separates them into the respective classes ofparticularanduniversal. Thus, "allhorses are animals," is auniversalJudgment; while "somehorses are black" is a particular Judgment. Thus all Judgments must be eitheraffirmativeornegative; and also eitherparticularoruniversal. This gives us four possible classes of Judgments, as follows, and illustrated symbolically:
1. Universal Affirmative, as "All A is B."2. Universal Negative, as "No A is B."3. Particular Affirmative, as "Some A is B."4. Particular Negative, as "Some A is not B."
1. Universal Affirmative, as "All A is B."
2. Universal Negative, as "No A is B."
3. Particular Affirmative, as "Some A is B."
4. Particular Negative, as "Some A is not B."
The Term or Judgment is said to be "distributed" (that is, extended universally) when it is used in its fullest sense, in which it is used in the sense of "each and every" of its kind or class. Thus in the proposition "Horses are animals" the meaning is that "each and every" horse is an animal—in this case thesubjectis "distributed" or made universal. But thepredicateisnot"distributed" or made universal, but remains particular or restricted and implies merely "some." For the proposition does not mean that the class "horses" includesallanimals. For we may say that: "Someanimals arenothorses." So you see we have several instances in which the "distribution" varies, both as regards the subject and also the predicate. The rule of logic applying in this case is as follows:
1. Inuniversalpropositions, thesubjectis distributed.2. Inparticularpropositions, thesubjectisnotdistributed.3. Innegativepropositions, thepredicateis distributed.4. Inaffirmativepropositions, thepredicateisnotdistributed.
1. Inuniversalpropositions, thesubjectis distributed.
2. Inparticularpropositions, thesubjectisnotdistributed.
3. Innegativepropositions, thepredicateis distributed.
4. Inaffirmativepropositions, thepredicateisnotdistributed.
A little time devoted to the analysis and understanding of the above rules will repay the student for his trouble, inasmuch as it will train his mind in the direction of logical distinction and judgment. The importance of these rules will appear later.
Halleck says: "Judgment is the power revolutionizing the world. The revolution is slow because nature's forces are so complex, so hard to be reduced to their simplest forms,and so disguised and neutralized by the presence of other forces. The progress of the next hundred years will join many concepts, which now seem to have no common qualities. If the vast amount of energy latent in the sunbeams, in the rays of the stars, in the winds, in the rising and falling of the tides, is treasured up and applied to human purposes, it will be a fresh triumph for judgment. This world is rolling around in a universe of energy, of which judgment has as yet harnessed only the smallest appreciable fraction. Fortunately, judgment is ever working and silently comparing things that, to past ages, have seemed dissimilar; and it is constantly abstracting and leaving out of the field of view those qualities which have simply served to obscure the point at issue." Brooks says: "The power of judgment is of great value to its products. It is involved in or accompanies every act of the intellect, and thus lies at the foundation of all intellectual activity. It operates directly in every act of the understanding; and even aids the other faculties of the mind in completing their activities and products."
The best method of cultivating the power of Judgment is the exercise of the faculty in the direction of making comparisons, of weighing differences and resemblances, and in generally training the mind along the lines of Logical Thinking. Another volume of this series is devoted to the latter subject, and should aid the student who wishes to cultivate the habit of logical and scientific thought. The study of mathematics is calculated to develop the faculty of Judgment, because it necessitates the use of the powers of comparison and decision. Mental arithmetic, especially, will tend to strengthen, and exercise this faculty of the mind.
Geometry and Logic will give the very best exercise along these lines to those who care to devote the time, attention and work to the task. Games, such as chess, and checkers or draughts, tend to develop the powers of Judgment. The study of the definitions of words in a good dictionary will also tend to give excellent exercise along the same lines. The exercises given in this book for the cultivation and development of the several faculties, will tend to develop this particular faculty in ageneral way, for the exercise of Judgment is required at each step of the way, and in each exercise.
Brooks says: "It should be one of the leading objects of the culture of young people to lead them to acquire the habit of forming judgments. They should not only be led to see things, but to have opinions about things. They should be trained to see things in their relations, and to put these relations into definite propositions. Their ideas of objects should be worked up into thoughts concerning the objects. Those methods of teaching are best which tend to excite a thoughtful habit of mind that notices the similitudes and diversities of objects, and endeavors to read the thoughts which they embody and of which they are the symbols."
The exercises given at the close of the next chapter, entitled "Derived Judgments," will give to the mind a decided trend in the direction of logical judgment. We heartily recommend them to the student.
The student will find that he will tend to acquire the habit of clear logical comparison and judgment, if he will memorize and applyin his thinking the following excellentPrimary Rules of Thought, stated by Jevons:
"I.Law of Identity: The same quality or thing isalwaysthe same quality or thing, no matter how different the conditions in which it occurs.
"II.Law of Contradiction: Nothing can at the same time and placebothbe and not be.
"III.Law of Excluded Middle: Everything musteitherbe, or not be; there is no other alternative or middle course."
Jevons says of these laws: "Students are seldom able to see at first their full meaning and importance. All arguments may be explained when these self-evident laws are granted; and it is not too much to say thatthe whole of logic will be plain to those who will constantly use these laws as their key."
DERIVED JUDGMENTS
As we have seen, a Judgment is obtained by comparing two objects of thought according to their agreement or difference. The next higher step, that of logical Reasoning, consists of the comparing of two ideas through their relation to a third. This form of reasoning is calledmediate, because it is effected through themediumof the third idea. There is, however, a certain process of Understanding which comes in between this mediate reasoning on the one hand, and the formation of a plain judgment on the other. Some authorities treat it as a form ofreasoning, calling itImmediate Reasoningor Immediate Inference, while others treat it as a higher form of Judgment, calling it Derived Judgment. We shall follow the latter classification, as best adapted for the particular purposes of this book.
The fundamental principle of Derived Judgment is that ordinary Judgments areoften so related to each other that one Judgment may be derived directly and immediately from another. The two particular forms of the general method of Derived Judgment are known as those of (1) Opposition; and (2) Conversion; respectively.
In order to more clearly understand the logical processes involved in Derived Judgment, we should acquaint ourselves with the general relations of Judgments, and with the symbolic letters used by logicians as a means of simplifying the processes of thought. Logicians denote each of the four classes of Judgments or Propositions by a certain letter, the first four vowels—A, E, I and O, being used for the purpose. It has been found very convenient to use these symbols in denoting the various forms of Propositions and Judgments. The following table should be memorized for this purpose:
Universal Affirmative, symbolized by "A."Universal Negative, symbolized by "E."Particular Affirmative, symbolized by "I."Particular Negative, symbolized by "O."
Universal Affirmative, symbolized by "A."Universal Negative, symbolized by "E."Particular Affirmative, symbolized by "I."Particular Negative, symbolized by "O."
It will be seen that these four forms of Judgments bear certain relations to eachother, from which arises what is called opposition. This may be better understood by reference to the following table called the Square of Opposition:
chart
Thus, A and E arecontraries; I and O aresub-contraries; A and I, and also E and O aresubalterns; A and O, and also E and I arecontradictories.
The following will give a symbolic table of each of the four Judgments or Propositions with the logical symbols attached:
(A) "All A is B."
(E) "No A is B."
(I) "Some A is B."
(O) "Some A is not B."
The following are the rules governing and expressing the relations above indicated:
I. Of the Contradictories:One must be true, and the other must be false. As for instance, (A) "All A is B;" and (O) "Some A is not B;" cannot both be true at the same time. Neither can (E) "No A is B;" and (I) "Some A is B;" both be true at the same time. They arecontradictoryby nature,—and if one is true, the other must be false; if one is false, the other must be true.
II. Of the Contraries:If one is true the other must be false; but, both may be false. As for instance, (A) "All A is B;" and (E) "No A is B;" cannot both be true at the same time. If one is true the othermustbe false.But, both may befalse, as we may see when we find we may state that (I) "SomeA is B." So while these two propositions arecontrary, they are notcontradictory. While, if one of them istruethe other must be false, it does not follow that if one isfalsethe other must betrue, for bothmay be false, leaving the truth to be found in a third proposition.
III. Of the Subcontraries:If one is false the other must be true; but both may be true. As for instance, (I) "Some A is B;" and (O) "Some A is not B;" may both be true, for they do not contradict each other. But one or the other must be true—they can not both be false.
IV. Of the Subalterns:If the Universal (A or E) be true the Particular (I or O) must be true. As for instance, if (A) "All A is B" is true, then (I) "Some A is B" must also be true; also, if (E) "No A is B" is true, then "Some A is not B" must also be true. The Universal carries the particular within its truth and meaning. But;If the Universal is false, the particular may be true or it may be false. As for instance (A) "All A is B" may be false, and yet (I) "Some A is B" may be either true or false, without being determined by the (A) proposition. And, likewise, (E) "No A is B" may be false without determining the truth or falsity of (O) "Some A is not B."
But:If the Particular be false, the Universal also must be false. As for instance, if (I) "Some A is B" is false, then it mustfollow that (A) "All A is B" must also be false; or if (O) "Some A is not B" is false, then (E) "No A is B" must also be false. But:The Particular may be true, without rendering the Universal true. As for instance: (I) "SomeA is B" may be true without making true (A) "AllA is B;" or (O) "Some A is not B" may be true without making true (E) "No A is B."
The above rules may be worked out not only with the symbols, as "All A is B," but also withanyJudgments or Propositions, such as "All horses are animals;" "All men are mortal;" "Some men are artists;" etc. The principle involved is identical in each and every case. The "All A is B" symbology is merely adopted for simplicity, and for the purpose of rendering the logical process akin to that of mathematics. The letters play the same part that the numerals or figures do in arithmetic or thea,b,c;x,y,z, in algebra. Thinking in symbols tends toward clearness of thought and reasoning.
Exercise: Let the student apply the principles of Opposition by using any of the above judgments mentioned in the preceding paragraph, in the direction of erecting a Square of Opposition of them, after having attached the symbolic letters A, E, I and O, to the appropriate forms of the propositions.
Then let him work out the following problems from the Tables and Square given in this chapter.
1. If "A" is true; show what follows for E, I and O. Also what follows if "A" befalse.
2. If "E" is true; show what follows for A, I and O. Also what follows if "E" befalse.
3. If "I" is true; show what follows for A, E and O. Also what follows if "I" befalse.
4. If "O" is true; show what follows for A, E and I. Also what happens if "O" befalse.
Judgments are capable of the process of Conversion, orthe change of place of subject and predicate. Hyslop says: "Conversion is the transposition of subject and predicate, or the process of immediate inference by which we can infer from a given preposition another having the predicate of the original for its subject, and the subject of the original for its predicate." The process of converting a proposition seems simple at first thoughtbut a little consideration will show that there are many difficulties in the way. For instance, while it is a true judgment that "Allhorsesareanimals," it is not a correct Derived Judgment or Inference that "Allanimalsarehorses." The same is true of the possible conversion of the judgment "All biscuit is bread" into that of "All bread is biscuit." There are certain rules to be observed in Conversion, as we shall see in a moment.
The Subject of a judgment is, of course,the term of which something is affirmed; and the Predicate isthe term expressing that which is affirmed of the Subject. The Predicate is really an expression of anattributeof the Subject. Thus when we say "All horses are animals" we express the idea thatall horsespossess theattributeof "animality;" or when we say that "Some men are artists," we express the idea thatsome menpossess theattributesor qualities included in the concept "artist." In Conversion, the original judgment is called the Convertend; and the new form of judgment, resulting from the conversion, is called the Converse. Remember these terms, please.
The two Rules of Conversion, stated in simple form, are as follows:
I. Do not change the quality of a judgment. The quality of the converse must remain the same as that of the convertend.
II. Do not distribute an undistributed term. No term must be distributed in the converse which is not distributed in the convertend.
The reason of these rules is that it would be contrary to truth and logic to give to a converted judgment a higher degree of quality and quantity than is found in the original judgment. To do so would be to attempt to make "twice 2" more than "2 plus 2."
There are three methods or kinds of Conversion, as follows: (1) Simple Conversion; (2) Limited Conversion; and (3) Conversion by Contraposition.
In Simple Conversion, there is no change in either quality or quantity. For instance, by Simple Conversion we may convert a proposition by changing the places of its subject and predicate, respectively. But as Jevons says: "It does not follow that the new one will always be true if the old one was true. Sometimes this is the case, and sometimes it is not. If I say, 'some churches are wooden-buildings,' I may turn it around and get 'some wooden-buildings are churches;' the meaning is exactly the same as before. This kind of change is called Simple Conversion, because we need do nothing but simply change the subjects and predicates in order to get a new proposition. We see that the Particular Affirmative proposition can be simply converted. Such is the case also with the Universal Negative proposition. 'No large flowers are green things' may be converted simply into 'no green things are large flowers.'"
In Limited Conversion, the quantity is changed from Universal to Particular. Of this, Jevons continues: "But it is a more troublesome matter, however, to convert a Universal Affirmative proposition. The statement that 'all jelly fish are animals,' is true; but, if we convert it, getting 'all animals are jelly fish,' the result is absurd. This is because the predicate of a universal proposition is really particular. We do not mean that jelly fish are 'all' the animals which exist, but only 'some' of the animals. The proposition ought reallyto be 'all jelly fish aresomeanimals,' and if we converted this simply, we should get, 'some animals are all jelly fish.' But we almost always leave out the little adjectivessomeandallwhen they would occur in the predicate, so that the proposition, when converted, becomes 'someanimals are jelly fish.' This kind of change is called Limited Conversion, and we see that a Universal Affirmative proposition, when so converted, gives a Particular Affirmative one."
In Conversion by Contraposition, there is a change in the position of the negative copula, which shifts the expression of the quality. As for instance, in the Particular Negative "Some animals are not horses," we cannot say "Some horses are not animals," for that would be a violation of the rule that "no term must be distributed in the converse which is not distributed in the convertend," for as we have seen in the preceding chapter: "In Particular propositions thesubjectisnotdistributed." And in the original proposition, or convertend, "animals" is thesubjectof a Particular proposition. Avoiding this, and proceeding by Conversion by Contraposition,we convert the Convertend (O) into a Particular Affirmative (I), saying: "Some animals are not-horses;" or "Some animals are things not horses;" and then proceeding by Simple Conversion we get the converse, "Some things not horses are animals," or "Some not-horses are animals."
The following gives the application of the appropriate form of Conversion to each of the several four kind of Judgments or Propositions:
(A)Universal Affirmative: This form of proposition is converted by Limited Conversion. The predicate not being distributed in the convertend, it cannot be distributed in the converse, by saying "all." ("In affirmative propositions thepredicateisnotdistributed.") Thus by this form of Conversion, we convert "All horses are animals" into "Some animals are horses." The Universal Affirmative (A) is converted by limitation into a Particular Affirmative (I).
(E)Universal Negative: This form of proposition is converted by Simple Conversion. In a Universal Negativeboth terms are distributed. ("In universal propositions, thesubjectis distributed;" "In negative propositions, thepredicateis distributed.") So we may say "No cows are horses," and then convert the proposition into "No horses are cows." We simply convert one Universal Negative (E) into another Universal Negative (E).
(I)Particular Affirmative: This form of proposition is converted by Simple Conversion. Forneither term is distributedin a Particular Affirmative. ("In particular propositions, thesubjectisnotdistributed. In affirmative propositions, thepredicateisnotdistributed.") And neither term being distributed in the convertend, it must not be distributed in the converse. So from "Some horses are males" we may by Simple Conversion derive "Some males are horses." We simply convert one Particular Affirmative (I), into another Particular Affirmative (I).
(O)Particular Negative: This form of proposition is converted by Contraposition or Negation. We have given examples and illustrations in the paragraph describing Conversion by Contraposition. The Particular Negative (I) is converted by contrapositioninto a Particular Affirmative (I) which is then simply converted into another Particular Affirmative (I).
There are several minor processes or methods of deriving judgments from each other, or of making immediate inferences, but the above will give the student a very fair idea of the minor or more complete methods.
Exercise: The following will give the student good practice and exercise in the methods of Conversion. It affords a valuable mental drill, and tends to develop the logical faculties, particularly that of Judgment. The student shouldconvertthe following propositions, according to the rules and examples given in this chapter:
1. All men are reasoning beings.2. Some men are blacksmiths.3. No men are quadrupeds.4. Some birds are sparrows.5. Some horses are vicious.6. No brute is rational.7. Some men are not sane.8. All biscuit is bread.9. Some bread is biscuit.10. Not all bread is biscuit.
1. All men are reasoning beings.2. Some men are blacksmiths.3. No men are quadrupeds.4. Some birds are sparrows.5. Some horses are vicious.6. No brute is rational.7. Some men are not sane.8. All biscuit is bread.9. Some bread is biscuit.10. Not all bread is biscuit.
REASONING
In the preceding chapters we have seen that in the group of mental processes involved in the general process of Understanding, there are several stages or steps, three of which we have considered in turn, namely: (1) Abstraction; (2) Generalization or Conception; (3) Judgment. Thefourthstep, or stage, and the one which we are now about to consider, is that called Reasoning.
Reasoningis that faculty of the mind whereby we compare two Judgments, one with the other, and from which comparison we are enabled to form a third judgment. It is a form of indirect or mediate comparison, whereas, the ordinary Judgment is a form of immediate or direct comparison. As, when we form a Judgment, we compare two concepts and decide upon their agreement or difference; so in Reasoning we compare two Judgments and from the comparison we draw or produce a new Judgment. Thus, we may reason that theparticular dog "Carlo" is an animal, by the following process:
(1)Alldogs are animals; (2) Carlo is a dog; therefore, (3) Carlo is an animal. Or, in the same way, we may reason that a whale is not a fish, as follows:
(1)Allfish are cold-blooded animals; (2) A whale isnota cold-blooded animal; therefore, (3) A whale isnota fish.
In the above processes it will be seen that the third and final Judgment is derived from a comparison of the first two Judgments. Brooks states the process as follows: "Looking at the process more closely, it will be seen that in inference in Reasoning involves a comparison of relations. We infer the relation of two objects from their relation to a third object. We must thus grasp in the mind two relations and from the comparison of these two relations we infer a third relation. The two relations from which we infer a third, are judgments; hence, Reasoning may also be defined as the process of deriving one judgment from two other judgments. We compare the two given judgments and from this comparison derive the third judgment. Thisconstitutes a single step in Reasoning, and an argument so expressed is called aSyllogism."
TheSyllogismconsists of three propositions, the first two of which express the grounds or basis of the argument and are called thepremises; the third expresses the inference derived from a comparison of the other two and is called theconclusion. We shall not enter into a technical consideration of the Syllogism in this book, as the subject is considered in detail in the volume of this series devoted to the subject of "Logic." Our concern here is to point out the natural process and course of Reasoning, rather than to consider the technical features of the process.
Reasoning is divided into two general classes, known respectively as (1)Inductive Reasoning; (2)Deductive Reasoning.
Inductive Reasoningis the process of arriving at a general truth, law or principle from a consideration of many particular facts and truths. Thus, if we find that a certain thing is true of a great number of particular objects, we may infer that the same thing is true ofallobjects of this particular kind. In one of the examples given above, one of the judgmentswas that "all fish are cold-blooded animals," which general truth was arrived at by Inductive Reasoning based upon the examination of a great number of fish, and from thence assuming thatallfish are true to this general law of truth.
Deductive Reasoningis the reverse of Inductive Reasoning, and is a process of arriving at a particular truth from the assumption of a general truth. Thus, from the assumption that "all fish are cold-blooded animals," we, by Deductive Reasoning, arrive at the conclusion that the particular fish before us must be cold-blooded.
Inductive Reasoning proceeds upon the basic principle that "What is true of the many is true of the whole," while Deductive Reasoning proceeds upon the basic principle that "What is true of the whole is true of its parts."
Regarding the principle ofInductive Reasoning, Halleck says: "Man has to find out through his own experience, or that of others, the major premises from which he argues or draws his conclusions. By induction, we examine what seems to us a sufficient number ofindividual cases. We then conclude that the rest of these cases, which we have not examined, will obey the same general law. The judgment 'All men are mortal' was reached by induction. It was observed that all past generations of men had died, and this fact warranted the conclusion that all men living will die. We make that assertion as boldly as if we had seen them all die. The premise, 'All cows chew the cud,' was laid down after a certain number of cows had been examined. If we were to see a cow twenty years hence, we should expect to find that she chewed the cud. It was noticed by astronomers that, after a certain number of days, the earth regularly returned to the same position in its orbit, the sun rose in the same place, and the day was of the same length. Hence, the length of the year and of each succeeding day was determined, and the almanac maker now infers that the same will be true of future years. He tells us that the sun on the first of next December will rise at a given time, although he cannot throw himself into the future to verify the conclusion."
Brooks says regarding this principle: "Thisproposition is founded on our faith in the uniformity of nature; take away this belief, and all reasoning by induction fails. The basis of induction is thus often stated to beman's faith in the uniformity of nature. Induction has been compared to a ladder upon which we ascend from facts to laws. This ladder cannot stand unless it has something to rest upon; and this something is our faith in the constancy of nature's laws."
There are two general ways of obtaining our basis for the process of Inductive Reasoning. One of these is called Perfect Induction and the other Imperfect Induction. Perfect Induction is possible only when we have had the opportunity of examining every particular object or thing of which the general idea is expressed. For instance, if we could examine every fish in the universe we would have the basis of Perfect Induction for asserting the general truth that "all fishes are cold-blooded." But this is practically impossible in the great majority of cases, and so we must fall back upon more or less Imperfect Induction. We must assume the general law from the fact that it is seen to exist in a very greatnumber of particular cases; upon the principle that "What is true of the many is true of the whole." As Halleck says regarding this: "Whenever we make a statement such as, 'All men are mortal,' without having tested each individual case or, in other words, without having seen every man die, we are reasoning fromimperfectinduction. Every time a man buys a piece of beef, a bushel of potatoes or a loaf of bread, he is basing his action on inference from imperfect induction. He believes that beef, potatoes and bread will prove nutritious food, although he has not actually tested those special edibles before purchasing them. They have hitherto been found to be nutritious on trial and he argues that the same will prove true of those special instances. Whenever a man takes stock in a new national bank, a manufactory or a bridge, he is arguing from past cases that this special investment will prove profitable. We instinctively believe in the uniformity of nature; if we did not we should not consult our almanacs. If sufficient heat will cause phosphorus to burn today, we conclude that the same result will follow tomorrow if the circumstances are the same."
But, it will be seen, much care must be exercised in making observations, experiments and comparisons, and in making generalizations. The following general principles will give the views of the authorities regarding this:
Atwater gives the two general rules:
Rule of Agreement: "If, whenever a given object or agency is present, without counteracting forces, a given effect is produced, there is a strong evidence that the object or agency is the cause of the effect."
Rule of Disagreement: "If when the supposed cause is present the effect is present, and when the supposed cause is absent the effect is wanting, there being in neither case any other agents present to effect the result, we may reasonably infer that the supposed cause is the real one."
Rule of Residue: "When in any phenomena we find a result remaining after the effects of all known causes are estimated, we may attribute it to a residual agent not yet reckoned."
Rule of Concomitant Variations: "When a variation in a given antecedent is accompanied by a variation of a given consequent, theyare in some manner related as cause and effect."
Atwater says, of the above rules, that "whenever either of these criteria is found, free from conflicting evidence, and especially when several of them concur, the evidence is clear that the cases observed are fair representatives of the whole class, and warrant a valid universal inductive conclusion."
We now come to what is known as Hypothesis or Theory, which is an assumed general principle—a conjecture or supposition founded upon observed and tested facts. Some authorities use the term "theory" in the sense of "a verified hypothesis," but the two terms are employed loosely and the usage varies with different authorities. What is known as "the probability of a hypothesis" is the proportion of the number of facts it will explain. The greater the number of facts it will explain, the greater is its "probability." A Hypothesis is said to be "verified" when it will account for all the facts which are properly to be referred to it. Some very critical authorities hold that verification should also depend upon there being no other possiblehypotheses which will account for the facts, but this is generally considered an extreme position.
A Hypothesis is the result of a peculiar mental process which seems to act in the direction of making a sudden anticipatory leap toward a theory, after the mind has been saturated with a great body of particular facts. Some have spoken of the process as almostintuitiveand, indeed, the testimony of many discoverers of great natural laws would lead us to believe that the Subconscious region of the mind is most active in making what La Place has called "the great guess" of discovery of principle. As Brooks says: "The forming of hypotheses requires a suggestive mind, a lively fancy, a philosophic imagination, that catches a glimpse of the idea through the form, or sees the law standing behind the fact."
Thomson says: "The system of anatomy which has immortalized the name of Oken, is the consequence of a flash of anticipation which glanced through his mind when he picked up in a chance walk the skull of a deer, bleached and disintegrated by the weather,and exclaimed, after a glance, 'It is part of a vertebral column.' When Newton saw the apple fall, the anticipatory question flashed through his mind, 'Why do not the heavenly bodies fall like this apple?' In neither case had accident any important share; Newton and Oken were prepared by the deepest previous study to seize upon the unimportant fact offered to them, and show how important it might become; and if the apple and the deer-skull had been wanting, some other falling body, or some other skull, would have touched the string so ready to vibrate. But in each case there was a great step of anticipation; Oken thought he saw the type of the whole skeleton in a single vertebra, whilst Newton conceived at once that the whole universe was full of bodies tending to fall."
Passing from the consideration of Inductive Reasoning to that of Deductive Reasoning we find ourselves confronted with an entirely opposite condition. As Brooks says: "The two methods of reasoning are the reverse of each other. One goes from particulars to generals; the other from generals to particulars. One is a process of analysis; the other is a process ofsynthesis. One rises from facts to laws; the other descends from laws to facts. Each is independent of the other; and each is a valid and essential method of inference."
Deductive Reasoningis, as we have seen, dependent upon the process of deriving a particular truth from a general law, principle or truth, upon the fundamental axiom that: "What is true of the whole is true of its parts." It is an analytical process, just as Inductive Reasoning is synthetical. It is a descending process, just as Inductive Reasoning is ascending.
Halleck says of Deductive Reasoning: "After induction has classified certain phenomena and thus given us a major premise, we proceed deductively to apply the inference to any new specimen that can be shown to belong to that class. Induction hands over to deduction a ready-made major premise,e.g.'All scorpions are dangerous.' Deduction takes this as a fact, making no inquiry about its truth. When a new object is presented, say a possible scorpion, the only troublesome step is to decide whether the object is really a scorpion. This may be a severe task on judgment. Theaverage inhabitant of the temperate zone would probably not care to risk a hundred dollars on his ability to distinguish a scorpion from a centipede, or from twenty or thirty other creatures bearing some resemblance to a scorpion. Here there must be accurately formed concepts and sound judgment must be used in comparing them. As soon as we decide that the object is really a scorpion, we complete the deduction in this way:—'All scorpions are dangerous;this creature is a scorpion;this creature is dangerous.' The reasoning of early life must be necessarily inductive. The mind is then forming general conclusions from the examination of individual phenomena. Only after general laws have been laid down, after objects have been classified, after major premises have been formed, can deduction be employed."
What is calledReasoning by Analogyis really but a higher degree of Generalization. It is based upon the idea that if two or more things resemble each other in many particulars, they are apt to resemble each other in other particulars. Some have expressed the principle as follows: "Things that have somethings in common have other things in common." Or as Jevons states it: "The rule for reasoning by analogy is that if two or more things resemble each other in many points, they will probably resemble each other also in more points."
This form of reasoning, while quite common and quite convenient, is also very dangerous. It affords many opportunities for making false inferences. As Jevons says: "In many cases Reasoning by Analogy is found to be a very uncertain guide. In some cases unfortunate mistakes are committed. Children are sometimes killed by gathering and eating poisonous berries, wrongly inferring that they can be eaten, because other berries, of a somewhat similar appearance, have been found agreeable and harmless. Poisonous toadstools are occasionally mistaken for mushrooms, especially by people not accustomed to gather them.... There is no way in which we can really assure ourselves that we are arguing safely by analogy. The only rule that can be given is this,that the more things resemble each other, the more likely is it that they are the same in other respects, especiallyin points closely connected with those observed."
Halleck says: "In argument or reasoning we are much aided by the habit of searching for hidden resemblances. We may here use the termanalogyin the narrower sense as a resemblance of ratios. There is analogical relation between autumnal frosts and vegetation on the one hand, and death and human life on the other. Frosts stand in the same relation to vegetation that death does to life. The detection of such a relation cultivates thought. If we are to succeed in argument, we must develop what some call a sixth sense for the detection of such relations.... Many false analogies are manufactured and it is excellent thought training to expose them. The majority of people think so little that they swallow false analogies just as newly-fledged robins swallow small stones dropped into their open mouths.... The study of poetry may be made very serviceable in detecting analogies and cultivating the reasoning powers. When the poet brings clearly to mind the change due to death, using as an illustration the caterpillar body transformed into the butterfly spirit, moving with winged ease over flowing meadows, he is cultivating our apprehension of relations, none the less valuable because they are beautiful."
There are certain studies which tend to develop the power or faculty ofInductive Reasoning. Any study which leads the mind to consider classification and general principles, laws or truth, will tend to develop the faculty of deduction. Physics, Chemistry, Astronomy, Biology and Natural History are particularly adapted to develop the mind in this particular direction. Moreover, the mind should be directed to an inquiry into thecausesofthings. Facts and phenomena should be observed and an attempt should be made not only to classify them, but also to discover general principles moving them. Tentative or provisional hypotheses should be erected and then the facts re-examined in order to see whether they support the hypotheses or theory. Study of the processes whereby the great scientific theories were erected, and the proofs then adduced in support of them, will give the mind the habit of thinking along the lines of logical induction. The question ever in themind in Inductive Reasoning is "Why?" The dominant idea in Inductive Reasoning is the Search for Causes.
In regard to the pitfalls of Inductive Reasoning—the fallacies, so-called, Hyslop says: "It is not easy to indicate the inductive fallacies, if it be even possible, in the formal process of induction.... It is certain, however, that in respect to the subject-matter of the conclusion in inductive reasoning there are some very definite limitations upon the right to transcend the premises. We cannot infer anything we please from any premises we please. We must conform to certain definite rules or principles. Any violation of them will be a fallacy. These rules are the same as those for material fallacies in deduction, so that the fallacies of induction, whether they are ever formal or not, are at least material; that is they occur whenever equivocation and presumption are committed. There are, then, two simple rules which should not be violated. (1) The subject-matter in the conclusion should be of the same general kind as in the premises. (2) The facts constituting thepremises must be accepted and must not be fictitious."
One may develop his faculty or power ofDeductive Reasoningby pursuing certain lines of study. The study of Mathematics, particularly in its branch of Mental Arithmetic is especially valuable in this direction. Algebra and Geometry have long been known to exercise an influence over the mind which gives to it a logical trend and cast. The processes involved in Geometry are akin to those employed in Logical reasoning, and must necessarily train the mind in this special direction. As Brooks says: "So valuable is geometry as a discipline that many lawyers and others review their geometry every year in order to keep the mind drilled to logical habits of thinking." The study of Grammar, Rhetoric and the Languages, are also valuable in the culture and development of the faculty of Deductive Reasoning. The study of Psychology and Philosophy have value in this connection. The study of Law is very valuable in creating logical habits of thinking deductively.
But in the study of Logic we have possibly the best exercise in the development and culture of this particular faculty. As Brooks well says: "The study of Logic will aid in the development of the power of deductive reasoning. It does this first by showing the method by which we reason. To know how we reason, to see the laws which govern the reasoning process, to analyze the syllogism and see its conformity to the laws of thought, is not only an exercise of reasoning, but gives that knowledge of the process that will be both a stimulus and a guide to thought. No one can trace the principles and processes of thought without receiving thereby an impetus to thought. In the second place, the study of logic is probably even more valuable because it gives practice in deductive thinking. This, perhaps, is its principal value, sincethe mind reasons instinctively without knowing how it reasons. One can think without the knowledge of the science of thinking, just as one can use language correctly without a knowledge of grammar; yet as the study of grammar improves one's speech, so the study of logic cannot but improve one's thought."
The study of the commonfallacies, such as "Begging the Question," "Reasoning in aCircle," etc., is particularly important to the student, for when one realizes that such fallacies exist, and is able to detect and recognize them, he will avoid their use in framing his own arguments, and will be able to expose them when they appear in the arguments of others.
The fallacy of "Begging the Question" consists in assuming as a proven fact something that has not been proven, or is not accepted as proven by the other party to the argument. It is a common trick in debate. The fact assumed may be either the particular point to be proved, or the premise necessary to prove it. Hyslop gives the following illustration of this fallacy: "Good institutions should be united; Church and State are good institutions; therefore, Church and State should be united." The above syllogism seems reasonable at first thought, but analysis will show that the major premise "Good institutions should be united" is a mere assumption without proof. Destroy this premise and the whole reasoning fails.
Another form of fallacy, quite common, is that called "Reasoning in a Circle," which consists in assuming as proof of a propositionthe proposition itself, as for instance, "This man is a rascal,because he is a rogue; he is a rogue,because he is a rascal." "We see through glass,because it is transparent." "The child is dumb,because it has lost the power of speech." "He is untruthful,because he is a liar." "The weather is warm,because it is summer; it is summer,because the weather is warm."
These and other fallacies may be detected by a knowledge of Logic, and the perception and detection of them strengthens one in his faculty of Deductive Reasoning. The study of the Laws of the Syllogism, in Logic, will give to one a certain habitual sense of stating the terms of his argument according to these laws, which when acquired will be a long step in the direction of logical thinking, and the culture of the faculties of deductive reasoning.
In concluding this chapter, we wish to call your attention to a fact often overlooked by the majority of people. Halleck well expresses it as follows: "Belief is a mental state which might as well be classed underemotionas under thinking, for it combines both elements. Belief is a part inference from theknown to the unknown, and part feeling and emotion." Others have gone so far as to say that the majority of people employ their intellects merely toproveto themselves and others that which theyfeel to be true, orwish to be true, rather than to ascertain what isactually trueby logical methods. Others have said that "men do not requireargumentsto convince them; they want onlyexcusesto justify them in their feelings, desires or actions." Cynical though this may seem, there is sufficient truth in it to warn one to guard against the tendency.
Jevons says, regarding the question of the culture of logical processes of thought: "Monsieur Jourdain, an amusing person in one of Moliere's plays, expressed much surprise on learning that he had been talking prose for more than forty years without knowing it. Ninety-nine people out of a hundred might be equally surprised on hearing that they had long been converting propositions, syllogizing, falling into paralogisms, framing hypotheses and making classifications with genera and species. If asked if they were logicians, they would probably answer, No. Theywould be partly right; for I believe that a large number even of educated persons have no clear idea of what logic is. Yet, in a certain way, every one must have been a logician since he began to speak. It may be asked:—If we cannot help being logicians, why do we need logic books at all? The answer is that there are logicians, andlogicians. All persons are logicians in some manner or degree; but unfortunately many people are bad ones and suffer harm in consequence. It is just the same in other matters. Even if we do not know the meaning of the name, we are allathletesin some manner or degree. No one can climb a tree or get over a gate without being more or less an athlete. Nevertheless, he who wishes to do these actions really well, to have a strong muscular frame and thereby to secure good health and personal safety, as far as possible, should learn athletic exercises."
CONSTRUCTIVE IMAGINATION
From the standpoint of the old psychology, a chapter bearing the above title would be considered quite out of place in a book on Thought-Culture, the Imagination being considered as outside the realm of practical psychology, and as belonging entirely to the idealistic phase of mental activities. The popular idea concerning the Imagination also is opposed to the "practical" side of its use. In the public mind the Imagination is regarded as something connected with idle dreaming and fanciful mental imaging. Imagination is considered as almost synonomous with "Fancy."
But the New Psychology sees beyond this negative phase of the Imagination and recognizes the positive side which is essentially constructive when backed up with a determined will. It recognizes that while the Imagination is by its very natureidealistic, yet these ideals may be made real—these subjective picturesmay be materialized objectively. The positive phase of the Imagination manifests in planning, designing, projecting, mapping out, and in general in erecting the mental framework which is afterward clothed with the material structure of actual accomplishment. And, accordingly, it has seemed to us that a chapter on "Constructive Imagination" might well conclude this book on Thought-Culture.
Halleck says: "It was once thought that the imagination should be repressed, not cultivated, that it was in the human mind like weeds in a garden.... In this age there is no mental power that stands more in need of cultivation than the imagination. So practical are its results that a man without it cannot possibly be a good plumber. He must image short cuts for placing his pipe. The image of the direction to take to elude an obstacle must precede the actual laying of the pipe. If he fixes it before traversing the way with his imagination, he frequently gets into trouble and has to tear down his work. Some one has said that the more imagination a blacksmith has, the better will he shoe a horse. Every time he strikes the red-hot iron, he makes itapproximate to the image in his mind. Nor is this image a literal copy of the horse's foot. If there is a depression in that, the imagination must build out a corresponding elevation in the image, and the blows must make the iron fit the image."
Brodie says: "Physical investigation, more than anything else, helps to teach us the actual value and right use of the imagination—of that wondrous faculty, which, when left to ramble uncontrolled, leads us astray into a wilderness of perplexities and errors, a land of mists and shadows; but which, properly controlled by experience and reflection, becomes the noblest attribute of man, the source of poetic genius, the instrument of discovery in science, without the aid of which Newton would never have invented fluxions nor Davy have decomposed the earths and alkalies, nor would Columbus have found another continent."
The Imagination is more than Memory, for the latter merely reproduces the impressions made upon it, while the Imagination gathers up the material of impression and weaves new fabrics from them or builds new structuresfrom their separated units. As Tyndall well said: "Philosophers may be right in affirming that we cannot transcend experience; but we can at all events carry it a long way from its origin. We can also magnify, diminish, qualify and combine experiences, so as to render them fit for purposes entirely new. We are gifted with the power of imagination and by this power we can lighten the darkness which surrounds the world of the senses. There are tories, even in science, who regard imagination as a faculty to be feared and avoided rather than employed. But bounded and conditioned by cooperant reason, imagination becomes the mightiest instrument of the physical discoverer. Newton's passage from a falling apple to a falling moon was, at the outset, a leap of the imagination."
Brooks says: "The imagination is a creative as well as a combining power.... The Imagination can combine objects of sense into new forms, but it can do more than this. The objects of sense are, in most cases, merely the materials with which it works. The imagination is a plastic power, moulding the things of sense into new forms to express its ideals; andit is these ideals that constitute the real products of the imagination. The objects of the material world are to it like clay in the hands of the potter; it shapes them into forms according to its own ideals of grace and beauty.... He, who sees no more than a mere combination in these creations of the imagination, misses the essential element and elevates into significance that which is merely incidental."
Imagination, in some degree or phase, must come before voluntary physical action and conscious material creation. Everything that has been created by the hand of man has first been created in themindof man by the exercise of the Imagination. Everything that man has wrought has first existed in his mind as anideal, before his hands, or the hands of others, wrought it into materialreality. As Maudsley says: "It is certain that in order to execute consciously a voluntary act we must have in the mind a conception of the aim and purpose of the act." Kay says: "It is as serving to guide and direct our various activities that mental images derive their chief value and importance. In anything that we purpose or intend to do, we must first of all have an ideaor image of it in the mind, and the more clear and correct the image, the more accurately and efficiently will the purpose be carried out. We cannot exert an act of volition without having in the mind an idea or image of what we will to effect."
Upon the importance of a scientific use of the Imagination in every-day life, the best authorities agree. Maudsley says: "We cannot do an act voluntarily unless we know what we are going to do, and we cannot know exactly what we are going to do until we have taught ourselves to do it." Bain says: "By aiming at a new construction, we must clearly conceive what is aimed at. Where we have a very distinct and intelligible model before us, we are in a fair way to succeed; in proportion as the ideal is dim and wavering we stagger and miscarry." Kay says: "A clear and accurate idea of what we wish to do, and how it is to be effected, is of the utmost value and importance in all the affairs of life. A man's conduct naturally shapes itself according to the ideas in his mind, and nothing contributes more to his success in life than having a high ideal and keeping it constantly in view. Where such isthe case one can hardly fail in attaining it. Numerous unexpected circumstances will be found to conspire to bring it about, and even what seemed at first hostile may be converted into means for its furtherance; while by having it constantly before the mind he will be ever ready to take advantage of any favoring circumstances that may present themselves."
Simpson says: "A passionate desire and an unwearied will can perform impossibilities, or what seem to be such, to the cold and feeble." Lytton says: "Dream, O youth, dream manfully and nobly, and thy dreams shall be prophets." Foster says: "It is wonderful how even the casualities of life seem to bow to a spirit that will not bow to them, and yield to subserve a design which they may, in their first apparent tendency, threaten to frustrate. When a firm decisive spirit is recognized it is curious to see how space clears around a man and leaves him room and freedom." Tanner says: "To believe firmly is almost tantamount in the end to accomplishment." Maudsley says: "Aspirations are often prophecies, the harbingers of what a man shall be in a condition to perform." Macaulay says: "It isrelated of Warren Hastings that when only seven years old there arose in his mind a scheme which through all the turns of his eventful life was never abandoned." Kay says: "When one is engaged in seeking for a thing, if he keep the image of it clearly before the mind, he will be very likely to find it, and that too, probably, where it would otherwise have escaped his notice." Burroughs says: "No one ever found the walking fern who did not have the walking fern in his mind. A person whose eye is full of Indian relics picks them up in every field he walks through. They are quickly recognized because the eye has been commissioned to find them."
Constructive Imagination differs from the phases of the faculty of Imagination which are akin to "Fancy," in a number of ways, the chief points of difference being as follows:
The Constructive Imagination is always exercised in the pursuance ofa definite intent and purpose. The person so using the faculty starts out with the idea of accomplishing certain purposes, and with the direct intent of thinking and planning in that particular direction. The fanciful phase of the Imagination, on the contrary, starts with no definite intent or purpose, but proceeds along the line of mere idle phantasy or day-dreaming.
The Constructive Imaginationselects its material. The person using the faculty in this manner abstracts from his general stock of mental images and impressions those particular materials which fit in with his general intent and purpose. Instead of allowing his imagination to wander around the entire field of memory, or representation, he deliberately and voluntarily selects and sets apart only such objects as seem to be conducive to his general design or plan, and which are logically associated with the same.
The Constructive Imagination operates upon the lines oflogical thought. One so using the faculty subjects his mental images, or ideas, to histhinking faculties, and proceeds with his imaginative constructive work along the lines of Logical Thought. He goes through the processes of Abstraction, Generalization or Conception, Judgment and the higher phases of Reasoning, in connection with his general work of Constructive Imagination. Instead of having the objects ofthought before him in material form, he has them represented to his mindin ideal form, and he works upon his material in that shape.
The Constructive Imagination isvoluntary—under the control and direction of the will. Instead of being in the nature of a dream depending not upon the will or reason, it is directly controlled not only by reason but also by the will.
The Constructive Imagination, like every other faculty of the mind, may be developed and cultivated by Use and Nourishment. It must be exercised in order to develop its mental muscle; and it must be supplied with nourishment upon which it may grow. Drawing, Composing, Designing and Planning along any line is calculated to give to this faculty the exercise that it requires. The reading of the right kind of literature is also likely to lead the faculty into activity by inspiring it with ideals and inciting it by example.
The mind should be supplied with the proper material for the exercise of this faculty. As Halleck says: "Since the imagination has not the miraculous power necessary to create something out of nothing, the firstessential thing is to get the proper perceptional material in proper quantity. If a child has enough blocks, he can build a castle or a palace. Give him but three blocks, and his power of combination is painfully limited. Some persons wonder why their imaginative power is no greater, when they have only a few accurate ideas." It thus follows that the active use of the Perceptive faculties will result in storing away a quantity of material, which, when represented or reproduced by the Memory, will give to the Constructive Imagination the material it requires with which to build. The greater the general knowledge of the person, the greater will be his store of material for this use. This knowledge need not necessarily be acquired at first hand from personal observation, but may also be in the nature of information acquired from the experience of others and known through their conversation, writings, etc.
The necessity of forming clear concepts is very apparent when we come to exercise the Constructive Imaginative. Unless we have clear-cut ideas of the various things concerned with the subject before us, we cannot focus theimagination clearly upon its task. The general ideas should be clearly understood and the classification should be intelligent. Particular things should be clearly seen in "the mind's eye;" that is, the power of visualization or forming mental images should be cultivated in this connection. One may improve this particular faculty by either writing a description of scenes or particular things we have seen, or else by verbally describing them to others. As Halleck says: "An attempt at a clear-cut oral description of something to another person will often impress ourselves and him with the fact that our mental images are hazy, and that the first step toward better description consists in improving them."
Tyndall has aptly stated the importance of visualizing one's ideas and particular concepts, as follows: "How, for example, are we to lay hold of the physical basis of light since, like that of life itself, it lies entirely without the domain of the senses?... Bring your imaginations once more into play and figure a series of sound-waves passing through air. Follow them up to their origin, and what do you there find? A definite, tangible, vibratingbody. It may be the vocal chords of a human being, it may be an organ-pipe, or it may be a stretched string. Follow in the same manner a train of ether waves to their source, remembering at the same time that your ether is matter, dense, elastic and capable of motions subject to and determined by mechanical laws. What then do you expect to find as the source of a series of ether waves? Ask your imagination if it will accept a vibrating multiple proportion—a numerical ratio in a state of oscillation? I do not think it will. You cannot crown the edifice by this abstraction. The scientific imagination which is here authoritative, demands as the origin and cause of a series of ether waves a particle of vibrating matter quite as definite, though it may be excessively minute, as that which gives origin to a musical sound. Such a particle we name an atom or a molecule. I think the seeking intellect, when focused so as to give definition without penumbral haze, is sure to realize this image at the last."
By repeatedly exercising the faculty of Imagination upon a particular idea, we add power and clearness to that idea. This is butanother example of the familiar psychological principle expressed by Carpenter as follows: "The continued concentration of attention upon a certain idea gives it a dominant power." Kay says: "Clearness and accuracy of image is only to be obtained by repeatedly having it in the mind, or by repeated action of the faculty. Each repeated act of any of the faculties renders the mental image of it more clear and accurate than the preceding, and in proportion to the clearness and accuracy of the image will the act itself be performed easily, readily, skillfully. The course to be pursued, the point to be gained, the amount of effort to be put forth, become more and more clear to the mind. It is only from what we have done that we are able to judge what we can do, and understand how it is to be effected. When our ideas or conceptions of what we can do are not based on experience, they become fruitful sources of error."
Galton says: "There is no doubt as to the utility of the visualizing faculty where it is duly subordinated to the higher intellectual operations. A visual image is the most perfect form of mental representation whereverthe shape, position and relation of objects in space are concerned. It is of importance in every handicraft and profession where design is required. The best workmen are those who visualize the whole of what they propose to do before they take a tool in their hands."
Kay says: "If we bear in mind that every sensation or idea must form an image in the mind before it can be perceived or understood, and that every act of volition is preceded by its image, it will be seen that images play an important part in all our mental operations. According to the nature of the ideas or images which he entertains will be the character and conduct of the man. The man tenacious of purpose is the man who holds tenaciously certain ideas; the flighty man is he who cannot keep one idea before him for any length of time, but constantly flits from one to another; the insane man is he who entertains insane ideas often, it may be, on only one or two subjects. We may distinguish two great classes of individuals according to the prevailing character of their images. There are those in whose mind sensory images predominate, and those whose images are chiefly such astend to action. Those of the former class are observant, often thoughtful, men of judgment and, it may be, of learning; but if they have not also the active faculty in due force, they will fail in giving forth or in turning to proper account their knowledge or learning, and instances of this kind are by no means uncommon. The man, on the other hand, who has ever in his mind images of things to be done, is the man of action and enterprise. If he is not also an observant and thoughtful man, if his mind is backward in forming images of what is presented to it from without, he will be constantly liable to make mistakes."
Galton says of the faculty of visualization: "Our bookish and wordy education tends to repress this valuable gift of nature. A faculty that is of importance in all technical and artistic occupations, that gives accuracy to our perceptions and justness to our generalizations, is starved by lazy disuse, instead of being cultivated judiciously in such a way as will, on the whole, bring the best return. I believe that a serious study of the best method of developing and using this faculty without prejudice to the practice of abstract thought insymbols, is one of the many pressing desiderata in the yet unformed science of education."