Imágenes de páginas
PDF
EPUB

Proof and cause.

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 relating 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.

[ocr errors]

In an argument, such as the example above given, it is, as has been said, impossible for any one, who admits both premises, to avoid ad

mitting the conclusion. But there will be freApparent ar- quently an apparent connection of premises with

a conclusion which does not in reality follow
from them, though to the inattentive or un-
skilful 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

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

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 one whose conclusion is obviously absurd, is often, and very advantageously, resorted to in addressing those who are ignorant of Logical rules;* but to lay down such rules, and employ them as a test, is evidently a safer and more compendious, as well as a more philosophical mode of proceeding. To attain these, it would plainly be necessary to analyze some clear and valid arguments, and to observe in what their conclusiveness consists.

Let us suppose, then, such an examination to be made of the syllogism above mentioned: “ whatever exhibits marks of design had an intelligent author; the world exhibits marks of design; therefore the world had an intelligent author.” In the first of these premises we find

* An exposure of some of Hume's fallacies in his Essay on Miracles” and elsewhere, was attempted, on this plan, a few years ago, in a pamphlet (published anonymously, as the nature of the argument required, but which I see no reason against acknowledging) entitled “ Historic Doubts relative to Napoleon Buonaparte;" in which it was shown that the existence of that extraordinary person could not, on Hume's principles, be received as a well-authenticated fact; since it rests on evidence less strong than that which supports the Scripture-histories.

For a clear development of the mode in which this last evidence operates on most minds, see “Hints on Inspiration,” p. 30–46.

it assumed universally of the class of “things which exhibit marks of design,” that they had an intelligent author; and in the other premiss, " the world” is referred to that class as comprehended in it: now it is evident, that whatever is said of the whole of a class, may be said of any thing comprehended in that class ; so that we are thus authorized to say of the world, that “it had an intelligent author.” Again, if we examine a syllogism with a negative conclusion, as, e.g. “nothing which exhibits marks of design could have been produced by chance: the world exhibits, &c.; therefore the world could not have been produced by chance :” the process of Reasoning will be found to be the same; since it is evident, that whatever is denied universally of any class may be denied of any thing that is comprehended in that class.

On further examination it will be found, that all valid arguments whatever may be easily reduced to such a form as that of the foregoing syllogisms; and that consequently the principle on which they are constructed is the UNIVERSAL PRINCIPLE of Reasoning. So elliptical, indeed, is the ordinary mode of expression, even of those who are considered as prolix writers, -i. e, so much is implied and left to be understood in the course of

argument, in comparison of what is actually stated,

[ocr errors]

(most men being impatient, even to excess, of any appearance of unnecessary and tedious formality of statement) that a single sentence will often be found, though perhaps considered as a single argument, to contain, compressed into a short compass, a chain of several distinct arguments. But if each of these be fully developed, and the whole of what the author intended to imply be stated expressly, it will be found that all the steps even of the longest and most complex train of reasoning, may be reduced into the above form.

It is a mistake (which might appear scarcely worthy of notice, had not so many, even esteemed writers, fallen into it) to imagine that Aristotle and other logicians meant to propose that this prolix form of unfolding arguments should universally supersede, in argumentative discourses, the common forms of expression; and that, “ to reason logically,” means, to state all arguments at full length in the syllogistic form : and Aristotle has even been charged with inconsistency for not doing so. It has been said, that “in his Treatises of Ethics, Politics, &c. he argues like a rational creature, and never attempts to bring his own system into practice.” *

As well might a chemist be charged with inconsistency for making use of any of the compound substances that are commonly

* Lord Kames.

« AnteriorContinuar »