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CHAP. V.
SECT. VI.

Erroneous classifications.

which is assumed to be the universal type of reasoning. To make clear the true psychological nature of the process which we are describing we shall examine some typical examples of it.

§ 170. We observe, in the first place, that mistakes are very apt to be made in the classifying of the objects with which we are acquainted, and a great deal of what passes for reasoning is simply an attempt to assign objects to their proper classes. There are many popular classifications which are erroneous in themselves and lead to other errors, and an important duty of scientific men is to correct these erroneous classifications. From our study of the formation of classes we can understand the manner in which a correct classification it to be effected and an erroneous one is to be avoided. It is only by the possession of the Essentia of a class, or at least of some universal characteristic of a class, that any object is to be referred to that class. Suppose, for example, that a person ignorant of natural history were to assert that whales belong to the class fish, his mistake would be corrected by informing him that whales do not possess the essential qualities of the class fish-they are not water-breathing or oviparous. Supposing him to know the principle of classification, he would immediately see that his predication regarding whales was incorrect. And upon discovering, or being informed, further, that whales are viviparous and suckle their young, and that these are the essential qualities of a class called mammal, he would at once refer them to that class.

Thus, in order to effect a correct classification, it is necessary to know by observation or instruction (1) what are the essential or characteristic qualities of some class in question, and (2) whether the object in question possesses or does not possess these qualities or characteristics. Knowing these two things, the mind at once refers, or does not refer, the object in question to the specified class.

§ 171. The preceding example, which illustrates the process of classification, when put by logicians into their favourite form of the syllogism, appears as follows:

"All fishes are oviparous animals:

Whales are not oviparous animals,
... Whales are not fishes."

We have already pointed out that the predicates of
propositions, as a rule, are connotative, and that,
therefore, it is psychologically incorrect to give
them extensive quantity. The first two of these
propositions therefore ought to be :-

"All fishes are oviparous:

:

Whales are not oviparous."

But, these two propositions being taken together, it becomes impossible to classify whales with fishes, and, consequently, the mind asserts-Whales are not contained in the class fish. Now, it must be observed that this is not an inference in the proper sense of that term. The so-called conclusion is directly seen the moment that the essential qualities of whales and fishes become known. If a boy have before him a number of marbles, and mixed up with them a number of hazel-nuts, he sees at a glance that the

CHAP. V.

SECT. VI.

The syllogism not the best

form for correcting false clas

sifications.

CHAP. V.
SECT. VI.

Incon

gruous predicates.

latter should not be classified with the former. The only difference between this case and the previous one is, that the qualities which make it impossible to classify the two sets of objects together are more obvious.

§ 172. Again, it is a principle of consistency between predications that two incongruous predicates cannot be attached to the same subject. To assert "The figure A is a square," and "The figure A is a circle," is a mental impossibility; and in practice the only difficulty is to see what predicates are incongruous, many predicates being frequently supposed to be incongruous which are not really so, and vice-versa. Now, much of so-called reasoning is nothing more than an attempt to show the congruity or incongruity of predicates. Suppose, for example, we take the proposition, "The sensualist, being enslaved by his appetites, cannot be free." When placed before our minds in this form there appears no difficulty in seeing immediately that "slavery to appetites" and "freedom" are incongruous, and cannot be predicated of the same individual. Logicians, however, must express it in the form of a syllogism, and so they say :

"No one is free who is enslaved by his appetites:

The sensualist is enslaved by his appetites,

... No sensualist is free."

We leave it to the reader to decide which is the most intelligible form.

Sometimes predicates are thought to be incongruous which are not really so, and the way in which

this error can be most easily corrected is to point out an instance in which the apparently incongruous predicates are plainly seen to be consistent. It might, for example, be supposed that certain modes of conduct which are consistent with holiness cannot at the same time be inexpedient. This hasty judg-. ment would at once be seen to be incorrect by pointing out some special circumstances in which it would be highly inexpedient to do some things which, after all, were quite consistent with holiness. But logicians would think that the simple pointing out of an instance to the contrary would not be enough to correct the error, and they would probably express themselves in some such way as this:

"Some practices which the Divine Law allows are in some
circumstances inexpedient;

All such practices are in themselves consistent with holiness:
... Some things in themselves consistent with holiness are

in some circumstances inexpedient."

CHAP. V.

SECT. VI.

reasoning

often not

§ 173. Many other examples might be given of Popular the manner in which erroneous classifications are corrected, and the consistency or inconsistency of inference. attributes or predicates determined. In popular language these processes are called reasoning; and logicians, basing much of their science upon this popular phraseology, do violence to psychology as well as to grammar by forcing them into the form of syllogisms. But, in truth, they are nothing more than the bringing together of related facts, and the perception of the relations between them. This being done, the so-called conclusion is not an unknown thing; it is directly seen. And the preliminary process is

CHAP. V. SECT. VII.

only the bringing of facts together so that it may be seen. Notwithstanding that this arrangement and harmonising of things known does not partake of the nature of inference, it is most important to human advancement and welfare that it should be well done. But the details of its accomplishment cannot be controlled by any rules more special than those general principles of classification and consistency to which we have referred. The work must depend chiefly upon the practical good sense and insight of the individuals who devote themselves to it.

Character of inference.

SECTION VII.

INFERENCE.

§ 174. We have already seen that Inference is one of the two grounds upon which predication rests, the other being Intuition. And the difference between the two is this, that, whereas in intuition we see directly the relation which is asserted in the predication, as well as the objects between which the relation exists, an inference asserts a relation which is not directly known, but which follows more or less immediately from what is so known. In our study of perception we have had under our notice many instances of inference. When we see an orange before us, we infer, or at least we may do so, that, if we cut open the skin, we shall see and touch certain small rounded elongated bodies called seeds. The reason why we infer this is that all the oranges

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