BOOK I.

ANALYTICAL OUTLINE OF THE SCIENCE.

$1.

In every instance in which we reason, in the strict sense of the word, i.e. make use of arguments, (I mean real, i.e. valid arguments,) whether for the sake of refuting an adversary, or of conveying instruction, or of satisfying our own minds on any point, whatever may be the subject we are engaged on, a certain process takes place in the mind which is one and the same in all cases, provided it be correctly conducted.

Of course it cannot be supposed that every one is even conscious of this process in his own mind; much less, is competent to explain the principles on which it proceeds. This indeed is, and cannot but be, the case with every other process respecting which any system has been formed; the practice not only may exist independently of the theory, but must have preceded the theory. There must have been Language before a system of Grammar could be devised; and musical compositions, previous to the Science of Music. This, by the way, will serve to expose the futility of the popular objection against Logic, that men may reason very well who know nothing of it. The parallel instances adduced, show that such an objection might be applied in many other cases, where its absurdity would be obvious; and that there is no ground for deciding thence, either that the system has no tendency to improve practice, or that even if it had not, it might not still be a dignified and interesting pursuit.

process

One of the chief impediments to the attainment of a just view of Reasoning the nature and object of Logic, is the not fully understanding, or similar in all not sufficiently keeping in mind, the SAMENESS of the reasoning- subjects. process in all cases. If, as the ordinary mode of speaking would seem to indicate, Mathematical reasoning, and Theological, and Metaphysical, and Political, &c., were essentially different from each other, i.e. different kinds of reasoning, it would follow, that supposing there could be at all any such science as we have described Logic, there must be so many different species, or at least different branches, of Logic. And such is perhaps the most prevailing notion. Nor is this much to be wondered at: since it is evident to all, that some men converse and write, in an argumenta

D

Origi: of
Logic.

tive way very justly on one subject, and very erroneously on another; in which again others excel, who fail in the former. This error may be at once illustrated and removed, by considering the parallel instance of Arithmetic; in which every one is aware that the process of a calculation is not affected by the nature of the objects, whose numbers are before us: but that (e.g.) the multiplication of a number is the very same operation, whether it be a number of men, of miles, or of pounds; though nevertheless persons may perhaps be found who are accurate in the results of their calculations relative to natural philosophy, and incorrect in those of political economy, from their different degrees of skill in the subjects of these two sciences; not surely because there are different arts of Arithmetic applicable to each of these respectively.

Others again, who are aware that the simple system of Logic may be applied to all subjects whatever, are yet disposed to view it as a peculiar method of reasoning, and not, as it is, a method of unfolding and analyzing our reasoning: whence many have been led (e.g. the author of the Philosophy of Rhetoric) to talk of comparing Syllogistic-reasoning with Moral-reasoning; taking it for granted that it is possible to reason correctly without reasoning logically; which is, in fact, as great a blunder as if any one were to mistake grammar for a peculiar language, and to suppose it possible to speak correctly without speaking grammatically. They have in short considered Logic as an art of reasoning; whereas (so far as it is an art) it is the art of reasoning; the logician's object being, not to lay down principles by which one may reason, but, by which all must reason, even though they are not distinctly aware of them: to lay down rules, not which may be followed with advantage, but which cannot possibly be departed from in sound reasoning. These misapprehensions and objections being such as lie on the very threshold of the subject, it would have been hardly possible, without noticing them, to convey any just notion of the nature and design of the logical system.

§ 2.

Supposing it then to have been perceived that the operation of Reasoning is in all cases the same, the analysis of that operation could not fail to strike the mind as an interesting matter of inquiry. And moreover, since (apparent) arguments which are unsound and inconclusive, are so often employed, either from error or design; and since even those who are not misled by these fallacies, are so often at a loss to detect and expose them in a manner satisfactory to others, or even to themselves; it could not but appear desirable to lay down some general rules of reasoning applicable to all cases; by which a pers might be enabled the more readily and clearly to state the grounds of his own conviction, or of his objection to the arguments of an opponent; instead of arguing at random, without

any fixed and acknowleged principles to guide his procedure. Such rules would be analogous to those of Arithmetic, which obviate the tediousness and uncertainty of calculations in the head; wherein, after much labour, different persons might arrive at different results, without any of them being able distinctly to point out the error of the rest. A system of such rules, it is obvious, must, instead of deserving to be called the "art of wrangling," be more justly characterised as the "art of cutting short wrangling," by bringing the parties to issue at once, if not to agreement, and thus saving a waste of ingenuity.

argument.

In pursuing the supposed investigation, it will be found that Analysis of every Conclusion is deduced, in reality, from two other propositions; (thence called Premises;) for though one of these may be, and commonly is, suppressed, it must nevertheless be understood as admitted; as may easily be made evident by supposing the denial of the suppressed premiss; which will at once invalidate the argument; e.g. if any one, from perceiving that "the world exhibits marks of design," infers that "it must have had an intelligent author," though he may not be aware in his own mind of the existence of any other premiss, he will readily understand, if it be denied that "whatever exhibits marks of design must have had an intelligent author," that the affirmative of that proposition is necessary to the validity of the argument.1 Or again, if any one on meeting with an animal which has horns on the head" infers that it is a ruminant," he will easily perceive that this would be no argument to any one who should not be aware of the general fact that "all horned animals ruminate."

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An argument thus stated regularly and at full length is called a Syllogism. Syllogism; which therefore is evidently not a peculiar kind of argument, but only a peculiar form of expression, in which every argument may be stated.2

When one of the premises is suppressed, (which for brevity's sake it usually is,) the argument is called an Enthymeme. And

1 Some choose to call this proposition not a premiss but merely a condition. This however is, substantially, (as has been formerly remarked) just what Logicians mean. Whoever has any good ground for believing his inference to be a just one, must believe this condition to exist.

2 Sonie writers, and Locke among others, who profess to despise what they call syllogistic reasoning," distinctly admit-as Locke does, e.g. in ch. xvii. that "all right reasoning may be reduced to the form of Syllogism;" (which is admitting the utmost that I conceive any Logician maintains) only, there are, he says, other and better" ways of reasoning:" that is, as he proceeds to explain, people lo not always, or usually, express their reasoning in a syllogistic form; as if any one had ever doubted that! Except in

deed it be a writer in the Edinburgh
Review, (in 1839,) who in deprecating
and deriding all attempts to adduce evi-
dences of the truth of Christianity, as
useless, and even dangerous, for the mass
of mankind, (a discovery, by the way,
which its first promulgators were not
enlightened enough to make) gives as a
reason, that the Gospel has been the
stay of countless millions who never
framed a syllogism." And very probable
it is, that Nicodemus for instance, and
those who deputed him, when he said

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we know that thou art a teacher sent from God; for no man can do these miracles that thou doest except God be with him," though he spoke grammatically and reasoned conclusively, may have never heard of syllogisms, or even of nouns and verbs.

Reason.

Proof and cause.

it may be worth while to remark, that when the argument is in this state, the objections of an opponent are (or rather appear to be) of two kinds; viz. either objections to the assertion itself, or objections to its force as an argument. E. G. In one of the above instances, an atheist may be conceived either denying that the world does exhibit marks of design, or denying that it follows from thence that it had an intelligent author. Now it is important to keep in mind that the only difference in the two cases is, that in the one, the expressed premiss is denied, in the other the suppressed; for the force as an argument of either premiss depends on the other premiss: if both be admitted, the conclusion legitimately connected with them cannot be denied.

It is evidently immaterial to the argument whether the Conclusion be placed first or last; but it may be proper to remark, that a Premiss placed after its Conclusion is called the Reason of it, and is introduced by one of those conjunctions which are called causal; viz. "since, because,' &c. which may indeed be employed to designate a Premiss, whether it came first or last. The illative conjunctions, "therefore," &c. designate the Conclusion.

It is a circumstance which often occasions error and perplexity, that both these classes of conjunctions have also another signification, being employed to denote, respectively, Cause and Effect, as well as Premiss and Conclusion: e.g. If I say, "this ground is rich, because the trees on it are flourishing," or "the trees are flourishing, and therefore the soil must be rich,' I employ these conjunctions to denote the connexion of Premiss and Conclusion; for it is plain that the luxuriance of the trees is not the cause of the soil's fertility, but only the cause of my knowing it. If again I say, "the trees flourish, because the ground is rich," or "the ground is rich, and therefore the trees flourish," I am using the very same conjunctions to denote the connexion of cause and effect; for in this case, the luxuriance of the trees, being evident to the eye, would hardly need to be proved, but might need to be accounted for.

There are, however, many cases in which the Cause is employed to prove the existence of its Effect; especially in arguments relat ing to future events; as e.g. when from favourable weather any one argues that the crops are likely to be abundant; the cause and the reason, in that case, coincide. And this contributes to their being so often confounded together in other cases.

§ 3.

In an argument, such as the examples above given, it is, as bas been said, impossible for any one, who admits both Premises, to avoid admitting the conclusion.

As the ancient atheists did.

4 As the modern atheists do.

The Major-premiss is often called the Principle; and the word Reason is then confined to the Minor.

See Appendix, No. I. art. Reason. See also Rhetoric, Part I. ch. 2, § fi.

A man may perhaps deny, or doubt, and require proof, that all animals that are horned do ruminate. Nay, it is conceivable that he may even not clearly understand what "ruminant" means; but still it will be not the less clear to him, that, supposing these Premises granted, the Conclusion must be admitted.

And even if you suppose a case where one or both of the Premises shall be manifestly false and absurd, this will not alter the conclusiveness of the Reasoning; though the conclusion tself may perhaps be absurd also. For instance," All the Ape-tribe are originally descended from Reptiles or Insects: Mankind are of the Ape-tribe; therefore Mankind are originally descended from Reptiles or Insects:" here, every one' would perceive the falsity of all three of these propositions. But it is not the less true that the conclusion follows from those premises, and that if they were true, it would be true also.

But there will be frequently an apparent connexion of Premises Apparent with a Conclusion which does not in reality follow from them, arguments. though to the inattentive or unskilful, the argument may appear to be valid. And there are many other cases in which a doubt may exist whether the argument be valid or not: i.e. whether it be possible or not to admit the Premises, and yet deny the Conclusion. It is of the highest importance, therefore, to lay down some regular form to which every valid argument may be reduced, and to devise a rule which shall show the validity of every argument in that form, and consequently the unsoundness of any apparent argument which cannot be reduced to it. E.G. If such an argument as this be proposed, "every rational agent is accountable; brutes are not rational agents; therefore they are not accountable:" or again, "all wise legislators suit their laws to the genius of their nation; Solon did this; therefore he was a wise legislator:" there are some, perhaps, who would not perceive any fallacy in such arguments, especially if enveloped in a cloud of words; and still more, when the conclusion is true, or (which comes to the same point) if they are disposed to believe it: and others might perceive indeed, but might be at a loss to explain, the fallacy. Now these (apparent) arguments exactly correspond, respectively, with the following, the absurdity of the conclusions from which is manifest: "every horse is an animal; sheep are not horses; therefore they are not animals;" and, "all vegetables grow; an animal grows; therefore it is a vegetable." These last examples, I have said, correspond exactly (considered as arguments) with the former; the question respecting the validity of an Argument, being, not whether the conclusion be true, but whether it follows from the premises adduced.

This mode of exposing a fallacy, by bringing forward a similar

Except certain French Naturalists.