For the validity and efficacy of such a process, two things are necessary, namely,— 1. That the general proposition which forms the first part of the statement, or, in logical language, the major proposition, be absolutely and universally true, or true without exception in regard to facts of a certain class, and be admitted as such by those to whom the reasoning is addressed. 2. That the fact referred to it, or the minor proposition, be admitted or proved to be one of that class of facts which are included under the general proposition. The conclusion then follows by a very simple process. If either of the two former propositions be deficient or untrue, the argument is false. Thus, if I had varied the statement as follows,-" Angels, like other human beings, are mortal;" there is a fallacy which, when put into the syllogistic form, is immediately apparent; thus, All human beings are mortal, The general or major proposition here is true; but the minor is not one of the class of facts which are included under it; therefore the conclusion is false. If I had said, again, "Angels, like other created beings, are mortal;" the fallacy is equally apparent, though from a different source; thus, All created beings are mortal, Here the minor proposition is true, or is a fact included under the first; but the first, or major, is not true, for we have no ground to believe that all created beings are mortal. On the other hand, when a general fact is assumed as true of a certain class of cases, we must not assume the converse as true of those which are not included in the class; thus, from the proposition, that all human beings are mor What necessary for. the validity of the process? The syllogistic form rendering false reasoning apparent. Example. Names of the propositions? tal, we are not entitled to infer that angels, who are not human beings, are immortal. Whether this conclusion be true or not, the argument is false; because the conclusion does not arise out of the premises ;-for, from the admitted general fact, that human beings are mortal, it does not follow, that all who are not human beings are not mortal. Yet this will be found a mode of fallacious reasoning of very frequent occurrence. The rule to be kept in mind for avoiding such fallacies is, that a general truth, which applies invariably to a certain class, may be applied to any individual which can be shown to be included in that class; but that we are not entitled to extend it to any which cannot be shown to belong to the class; and that we are not to assume the reverse to be true of those which do not be long to it. On the other hand, we are not to assume a property as belonging to a class, because we have ascertained it to belong to a certain number of individuals. This error comes under another part of our subject, and has been already alluded to under the head of false generalization. The syllogism, therefore, cannot properly be considered an engine for the discovery of truth, but rather for enabling us to judge of the application of, and deductions from truths previously ascertained. For, before we can construct such a process as constitutes the syllogism, we require to have premised that most important process of investigation by which a fact is ascertained to be general in regard to all the individuals of a class; and, likewise, that certain individuals specified in the argument belong to this class. Thus, the syllogism was nothing more than that process of mind which we exercise every time when we examine the validity of an argument, though we may not always put it into this systematic form. And yet there may often be advantage in doing so, as it enables us to examine the elements of the arguments more distinctly apart. It is related of an eminent English barrister, afterward a distinguished judge, that, on one occasion, he was completely puzzled by an argument adduced by his opponent in an important case, and that he did not detect the fallacy till he went home and put it into the form of a syllogism. Though General rules in all such reasoning? Real nature of the syllogism? Advantage of it? Anecdote of the English lawyer. a syllogism, therefore, may not lead to any discovery of truth, it may be an important instrument in the detection of sophistry, by directing the attention distinctly and separately to the various elements which compose a statement or an argument, and enabling us to detect the part in which the sophistry is involved. In every process of reasoning there are two distinct objects of attention, or circumstances to be examined, before we admit the validity of the argument. These are,--the premises or data which the reasoner assumes, and which he expects us to admit as true, and the conclusions which he proposes to found upon these premises. The premises again consist of three parts, which we require to examine sepa rately and rigidly. These are, 1. Certain statements which he brings forward as facts, and which he expects to be admitted as such. 2. Certain principles or propositions which he assumes as first truths, or articles of belief universally admitted. 3. Certain other propositions which he refers to, as deductions from former processes of investigation, or processes of reasoning. If the statements referable to these three heads are admitted as true, the argument proceeds, and we have only to judge of the validity or correctness of his farther deductions. If they are not at once admitted, the argument cannot proceed till we are satisfied on these preliminary points. If we do not admit his facts, we require him to go back to the evidence on which they rest. If we no not admit the general propositions which he assumes, we require the processes of reasoning or investigation on which these are founded. When we are at last agreed upon these premises, we proceed to judge of the conclusions which he proposes to deduce from them. The circumstances now referred to may be considered as the essential parts of a process of reasoning, in a logical view; but there is another point which we require to keep carefully in mind in examining such a process, and that is, Utility of the syllogism? Objects of attention in reasoning? How many anl what? Premises; how many parts? Examination of these premises? Use of terms. the use of terms. Much of the confusion and perplexity in reasoning consists in the ambiguity of the terms; this is referable to three heads, namely: 1. Terms of a vague and indefinite character, the precise import of which has not been defined. 2. Terms employed in a sense in some respect different from their common and recognised acceptation. 3. Varying the import of a term, so as to use it in different meanings in different parts of the same argument; or employing it at different times in degrees of comprehension and extension. In examining the validity of a process of reasoning, then, the mental operation which we ought to perform may be guided by the following considerations : 1. What statements does the author propose as matters of fact;-are these authentic; are they all really bearing upon, or connected with the subject; do they comprise a full and fair view of all the facts which ought to be brought forward in reference to the inquiry: or have we reason to suspect that any of them have been disguised or modified,— that important facts have been omitted or kept out of view, -that the author has not had sufficient opportunities of acquiring the facts which he ought to have been possessed of, -or that he has been collecting facts on one side of a question, or in support of a particular opinion? 2. What propositions are assumed, either as first or intuitive truths, or as deductions arising out of former processes of investigation; and are we satisfied that these are all legitimate and correct? In particular, does he make any statement in regard to two or more events being connected as cause and effect; and is this connection assumed on sufficient grounds-does he assume any general principle as applicable to a certain class of facts; is this principle in itself a fact, and does it really apply to all the cases which he means to include under it; have we any reason to believe that it has been deduced from an insufficient number of facts; or is it a mere fictitious hypothesis, founded upon a principle which cannot be proved to have a real existence ? 3. Do these assumed principles and facts really belong Sources of ambiguity? Considerations which should guide in examining reasoning? As to matters of faet? Cautions? Proposition assumed? Cautions in regard to them. Connection between the principles and facts ? to the same subject, or, in other words, do the facts belong to that class to which the principles apply? 4. Are the leading terms which he employs fully and distinctly defined as to their meaning; does he employ them in their common and recognised acceptation; and does he uniformly use them in the same sense; or does he seem to attach different meanings to the same term in different parts of his argument? 5. What are the new conclusions which he deduces from the whole view of the subject; are these correct and valid; and do they really follow from the premises laid down in the previous part of his argument? For on this head it is always to be kept in mind that a conclusion may be true, while it does not follow from the argument which has been brought to prove it; in such a case the argument is false. Much of the confusion, fallacy, and sophistry of reasoning arises from these points not being sufficiently attended to, and distinctly and rigidly investigated. An argument may appear fair and consecutive, but when we rigidly examine it we may find that the reasoner has, in his premises, contrived to introduce some statement which is not true in point of fact, or some bold general position which is not correct, or not proved; or that he has left out some fact, or some principle, which ought to have been brought forward in a prominent manner, as closely connected with the inquiry. Hence the necessity for keeping constantly in view the various sources of fallacy to which every process of reasoning is liable, and for examining the elements rigidly and separately before we admit the conclusion. A process of reasoning is to be distinguished from a process of investigation; and both may be illustrated in the following manner: All reasoning must be founded upon facts, and the ascertained relations of these facts to each other, The nature of these relations has already been mentioned, as referable to the various heads of resemblance, cause, effect, &c. The statement of an ascertained relation of two facts to each other is called a proposition, such as,—that A Use of terms? Conclusions? Importance of attending to these points? Distinction between reasoning and investigation Foundation of reasoning? Proposition,-what? |