CHAPTER XVIII.

BLUNDERS IN WORD AND BLUNDERS IN THOUGHT.

FALLACIES or blunders in reasoning are usually divided into two great classes: 'Logical' or 'Formal' (Fallaciæ in dictione) and Non-logical' or 'Material' (Fallaciæ extra dictionem or in re). When logic is regarded as a science of the forms of thought' or the science which treats of the proper arrangement of words in correct thinking (on the assumption that the 'forms' of thought and the forms or arrangements of words correspond) this distinction presents no difficulties: logical or formal fallacies are those which result from a violation of the rules which logic lays down for correct thinking and the corresponding arrangement of words; and material or non-logical fallacies are those which occur in spite of the observance of these rules—they do not depend upon the general laws of thought or arrangement of words at all, and can only be avoided by a knowledge of the matter thought about.

In the foregoing pages I hope it has been made plain that the same arrangement or form of words cannot be counted upon to always express the same thought. I hope it has been made plain too that the so-called 'laws' and 'forms' of thought with which it is often said that logic deals have no meaning whatever apart from the things thought about and the way in which the relations of these things involve each other. If these views are correct it is quite impossible to make any fundamental distinction between fallacies which

are due to some perversion of the forms of thought and those which are due to some mistake about the relations of things. But we might still distinguish between fallacies which are due to some misconception about the 'matter' under discussion and those which depend in some way upon the 'form' of words used in discussing it. So with the terms 'logical' and 'extra-logical'. They may be taken to mean that some fallacies result from a violation of logic while others do not, or they may be taken to mean that some are, and others are not, concerned with logoi or words.

Now it is true that logic has not made such elaborate provision against every fallacy possible as it makes against those already discussed, and yet fallacious thinking is always illogical and there is no reason but one of convenience why books on logic should discuss some and not others. It is not appropriate therefore to divide fallacies into those that violate the rules of logic and those that do not. But there is a reason why we should divide fallacies into those that result in some way from the improper use of words and those that do not. We may therefore accept this division into 'logical' and 'extra-logical' or 'material' on the understanding that it is equivalent to a division into blunders that result mainly from the careless use of words and those that do not.

The 'logical' fallacies are usually subdivided into two classes called 'Purely logical', where the fallaciousness is apparent from the mere form of expression", and‘Semilogical', where the fallaciousness is not apparent from the mere form of expression but is due to some ambiguity in the language used or some misunderstanding as to its meaning. Of the semi-logical' fallacies we shall have nothing more to say. We have seen already how insidious they are, why they arise, and how best to guard against them.

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With the purely logical' fallacies we are also familiar. They are such blunders as we make when we ignore the cautions of the syllogism, or convert A simply or O at all, or

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Purely logical.'

reason that because all S is P all non-S is non-P, or infer the falsity of a consequent from the falsity of its antecedent, or the truth of the antecedent from the truth of the consequent, or the falsity of a conclusion from the falsity of the premises, or the truth of the premises from the truth of the conclusion. In all such cases it is apparent from the mere form of expression' that the reasoning is inconclusive; the blunder can be detected without inquiring into the truth of the premises or even into the meaning of the terms; so that a purely logical fallacy, unlike any of the others, can be detected when the terms are mere unmeaning words or symbols such as S, M and P, or X, Y and Z.

The strange thing about these so-called purely logical fallacies is that they are committed so often. How is it possible, we may ask, to think so badly? If the reader will ask the following questions to some unsuspecting person and does not allow very much time to elapse between the answering of one and the asking of the next, the result of the experiment may help to make the matter clear:

Who was the first man?

Who was the first woman?
Who killed Cain?

Abel did not kill Cain, but his name will usually be mentioned, or at least come to mind, merely because it comes naturally at the end of the series' Adam, Eve, Cain' and fits into the atmosphere of murder. It is largely a mere matter of the verbal jingle, the answer resulting from the same law of habit in the nervous system that accounts for putting one's pen in the paste-pot after using the brush. Most of these so-called purely logical fallacies come in precisely the same way. Inference is in the air and the jingle seems to fit, so we spurt out something when the premises will not justify any inference whatever, or an 'All' or a 'No' that fits the jingle when the premises justify only a Some'.

If we say:

... No X is Z;

... No X is Z,

it is not valid though we have merely substituted 'No' for All' or 'No X' for All X' throughout, without affecting the jingle. Indeed if we had only said 'No-X' instead of No X' the reasoning in the last case would have been precisely similar to that in the first and just as valid. Again if we say

Five francs are a dollar;

Four shillings are a dollar;

... Five francs are four shillings,

the inference is perfectly valid; but if we say in precisely similar form

Blades of grass are green;

Frogs are green;

... Blades of grass are frogs,

the inference is not valid. The reason is, of course, that the copulaare' is used in different senses in the two syllogisms; but when we do not stop to think of the sense, the familiar jingle, assisted perhaps in this case by some recollection of Euclid's axiom that things equal to the same thing are equal to each other', lures us on to danger.

In spite of a real confusion of meaning sometimes associated with some of these 'purely logical fallacies', they can hardly be called the result of bad thinking; because they are not the result of thinking at all, but only of a reflex act. On this account it might have been more appropriate to call them the Reflex Fallacies or the Jingle Fallacies.

As there are two classes of verbal fallacies, so also there

Two kinds

fallacies.

are two classes of the material or non-verbal fallacies, wh may be called respectively Fallacies of the Forgotten Issue and Fallacies of the Ill-conceived of material Universe. Fallacies of the Forgotten Issue are not particularly characteristic of deduction; but some of them are usually discussed in connection with it, and therefore we shall speak of them in the next chapter. In the chapter after that we shall discuss Fallacies of the Ill-conceived Universe. These do not belong to the traditional field of deduction, because there are no rules for verbal manipulation which they break. Yet I have tried to show that all deductive inference depends upon the assumption that things have certain general relations, and that deductive fallacies occur when these relations are overlooked; and if this is correct these fallacies of the Ill-conceived Universe are essentially similar to the fallacies of deduction in their ultimate nature, though they may not be caused like them by a verbal jingle.

Nothing has been said in the foregoing pages about the fallacy known as 'Non Sequitur'. This name is really applicable, as the words imply, to every argument Non

in which the conclusion does not follow, and in Sequitur. this sense of the words every fallacy is a Non Sequitur. But the phrase is often applied in a more restricted sense to those arguments only in which the conclusion does not even appear to follow, except perhaps to the most hasty and careless of reasoners; as in the following examples: The earth is round; therefore there is no atmosphere on the moon. "Every one desires happiness, and virtuous people are happy, therefore every one desires to be virtuous." Episcopacy is of Scripture origin, the Church of England is the only established church in England; ergo the church established is the church that should be supported." The subject requires no further consideration.

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