CHAPTER X

THE PITFALLS OF REASONING

Euthydemus replied: And do you think, Ctesippus, that it is possible to tell a lie?

Yes, said Ctesippus, I should be mad to deny that.

And in telling a lie do you tell the thing of which you speak or not? You tell the thing of which you speak.

And he who tells, tells that which he tells and no other?

Yes, said Ctesippus.

And that is a distinct thing apart from other things?

Certainly.

And he who says that thing says that which is?

Yes.

And he who says that which is, says the truth, and therefore Dionysodorus, if he says that which is, says the truth of you and no lie.

Dangers in reasoning. The above conversation, from the days of the Greek Sophists, shows how subject to subtle error are even the seemingly most exact forms of reasoning. Indeed, unless formal reasoning is carefully guarded it is likely to lead to as distorted and erroneous results as the loosest sort of unorganized thinking. Its "since" and its "therefore" give it a degree of plausibility that is hard to combat, and often carry for it a conviction to which its soundness does not entitle it. Almost anything can be proved with a show of logic. There is even a famous mathematical method of proving that one is equal to two. Now formal reasoning we neither can, nor would wish to, forego, but it is worth our while to know its pitfalls and to guard

against them. This subject is, of course, too big, and involves too many technicalities, to be adequately treated here, and for a fuller discussion the reader is referred to textbooks on Logic. Nevertheless it is hoped that some of the more serious pitfalls may be successfully pointed out here.

Accident.

MATERIAL FALLACIES

There is a famous old syllogism to this effect:

What you bought yesterday you eat to-day.

You bought raw meat yesterday.

Therefore you must eat raw meat to-day.

Another, illustrating the same fallacy, is as follows:

Pine wood is good for lumber.

Matches are pine wood.

Therefore matches are good for lumber.

Now these syllogisms both look plausible enough, yet one knows that the conclusion does not follow properly from the given facts or premises as they are technically called. Why? For this reason: in the premise "What you bought yesterday you eat to-day," one refers only to the essence of the material purchased - its general nature. One does not have in mind at all its accidental properties. That it is cooked or uncooked is a matter to which one's attention has not gone. In the second premise, however, "You bought raw meat yesterday," the emphasis is upon the unessential feature that it was raw. Between the premises one's attitude has vitally shifted. The first premise hinges upon the essence; the second upon an accident. In the second syllogism the same shifting takes place. Pine wood is good for lumber only in essence when other conditions are normal. But matches do not represent an essential form of pine wood, but a highly accidental one. Here again the fallacy grows out of a shifting of viewpoint. This shifting from the essential to the unessential, or from the unessential to

the essential, gives rise to what is called the Fallacy of Accident.

Accident in popular reasoning. Now it would be a matter of little consequence to know of this error if the fallacy were confined to such glaring cases as those of the above illustrations. But unfortunately it occurs constantly in the most subtle forms, and perhaps daily we are misled by it. We are urged to vote for Mr. P. because he is a Republican, and because Republicans should stand by their party. But when we admit that Republicans should stand by their party we mean only so long as the point at issue is the essence of Republicanism. In this case, however, Mr. P. may be a notorious political boss, and his attitude may not be representative of the inner heart of the Republican Party at all. In the one premise the matter turns, then, upon the essence of Republicanism; in the next upon a mere peculiarity of a member of that party. And thus in attempting to drive the conclusion upon us the Fallacy of Accident has been committed.

Again we admit that students should be loyal to their schoolmates. But that means when conditions are normal. If the matter comes to turn, as it often does, upon the accident that this particular schoolmate has been clearly in the wrong, the general proposition no longer necessarily holds. To attempt to claim support under these abnormal conditions is to commit the Fallacy of Accident.

Converse accident. - A similar error led to the former insistence upon every one's studying Greek. A very few persons derived a high type of culture from this study those who had the necessary temperament, and who could stay by the subject long enough to get into the spirit of it. But because it had proved good for them it was urged as good in general and for everybody, despite the fact that the premise upon which this conclusion rested represented an accidental and not a general condition of the study of Greek.

Between the premises the shift was made from the accident to the essence, just as in the cases cited above it was made from the essence to the accident.

Composition. There is a second fallacy into which we are all prone to fall. We may best understand it if it is approached through examples. European countries as a whole have always distrusted a democracy. They rest this distrust upon the fact that most voters are ignorant, and that hence the aggregate vote is an ignorant vote. But any one who has had anything to do with groups knows that one can pretty safely trust the conclusions of any fairly large number of men, provided conditions are normal. For some will be erratic in one direction while others are erratic in another. They will thus offset each other and will be characterized as a group by a quality that does not belong to any one of them individually. In like manner the verdict of a jury may be trustworthy, though that of each member taken separately would be highly untrustworthy. A mass of testimony, too, may be as a whole conclusive, even though all of its parts taken separately may be subject to legitimate doubt. Thus the ignorance of the whole voting population, or of the whole jury, does not follow from summing up the ignorance of its individual members, nor the untrustworthiness of the whole of the evidence from the untrustworthiness of its several parts. The whole has a character that is more than the sum of the parts. To assume the opposite, and to draw a conclusion regarding the whole merely by aggregating its several parts is to commit this second kind of fallacy the Fallacy of Composition.

Illustrations. This fallacy is further illustrated by the stock arguments in favor of a high protective tariff. A high rate on wool is advantageous to the sheep raiser, a high rate on manufactured goods to the manufacturer, a high rate on beef to the meat packer, etc. Therefore, it is concluded, a high rate on everything at the same time would

be an advantage to us all. This conclusion overlooks the fact that, while we might profit severally by these protective duties, they may be of no profit to us when all are taken together, since what we would gain for ourselves would be offset by the higher prices which, in consequence, we would have to pay for what we purchased.

Athletes sometimes commit this fallacy when they indulge individually in "grandstand feats." As a matter of fact the most hopeless sort of team is that one in which each member attempts to "star." star." Good team playing does not result from an aggregation of the spectacular feats of individual members, but from their subordination to the unity of the group. Whether in acting, or in thinking, or in feeling, every group is much more than the aggregate of its members, and whoever attempts to treat it merely as an aggregate inevitably fails in the undertaking.

Division. There is also a converse fallacy to this one of composition namely, the Fallacy of Division. It is exactly the reverse of Composition. What is true of the whole is not necessarily true of the parts. From the fact that Congress passes a measure it does not follow that member B is responsible. If a town is boorish, Jones, who lives there, is not necessarily so. If an education as a whole is valuable, it does not follow that every one of the subjects studied in getting it is worth while. If a crowd is unreasonable, the conclusion is unwarranted that its members, when taken aside, will be. The parts are no more miniature representations of the whole than the members of an animal's body are duplications of that organism. To assume that they are, and to attempt to pass from the whole to a conclusion about the parts, is to commit the fallacy of Division.

Begging the question. A sermon which I once heard illustrates a fourth fallacy. The sermon was based upon the text, "All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for in