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Of the use of the forms of right reasoning.

It is not understood by most persons that the proper use of inferences and hypotheses and interrogations, and logical forms generally, has any relation to the duties of life. In every matter of action the question is, how a wise and good man may come honestly and consistently out of it. We must admit, therefore, either that the wise man will not engage in difficult problems or that, if he does, he will not think it worth his care to deal with them thoroughly; or if we allow neither of these alternatives, it is necessary to confess that some examination ought to be made of those points on which the solution of these problems chiefly depends. For what is reasoning? To lay down true positions, to reject false ones, and to suspend the judgment in doubtful ones. Is it enough, then, to have learned merely this? It is enough, say you. Is it enough, then, for him who would not commit any mistake in the use of money, merely to have heard that we are to receive the good pieces, and to reject the bad? This is not enough. What must be [p. 1028] added besides? That skill which tries and distinguishes what pieces are good, what bad. Therefore, in reasoning too, the definition just given is not enough; but it is necessary that we should be able to prove and distinguish between the true and the false and the doubtful. This is clear.

And what further is attempted in reasoning? To admit the logical consequence of whatever you have properly granted. Well, and is it enough merely to know this necessity? It is not; but we must learn how it happens that such a thing is the consequence of such another, and when one thing follows from one premise, and when from many premises. Is it not moreover necessary that he who would acquit himself skilfully in reasoning should both himself demonstrate whatever he asserts and be able to comprehend the demonstrations of others, and not be deceived by such as use sophistry as if they were reasoning fairly? Hence arises the use and practice of logical forms; and it appears to be indispensable.

But it may possibly happen that from the premises which we have honestly granted there arises some consequence which, though false in itself, is nevertheless a fair inference. What then ought I to do? To admit a falsehood? Impossible. To take back my concessions? But this will not be allowed. Or assert that the consequence does not fairly follow from the premises? Nor is even this practicable. What then, is to be done in the case? Is it not this? As [p. 1029] the having once borrowed money is not enough to make a person a debtor, unless he still continues to owe money and has not paid it, so the having granted the premises is not enough to make it necessary to grant the inference, unless we continue our concessions. If the premises continue to the end such as they were when the concessions were made, it is absolutely necessary to continue the concessions, and to admit what follows from them. But if the premises do not continue such as they were when the concession was made, it is absolutely necessary to revoke the concession, and refuse to accept the inference. For this inference is no consequence of ours, nor belongs to us, when we have revoked the concession of the premises. We ought then thoroughly to consider our premises and their different aspects, on which any one, by laying hold, - either on the question itself or on the answer, or on the inference, or elsewhere, -may embarrass the unthinking who did not foresee the result. So that in this way we may not be led into any unbecoming or confused position.

The same thing is to be observed in hypotheses and hypothetical arguments. For it is sometimes necessary to require some hypothesis to be granted, as a kind of step to the rest of the argument. Is every given hypothesis, then, to be granted, or not every one? and if not every one, which? And is he who has granted an hypothesis forever to abide by it ! Or is he sometimes to revoke it, and admit only conse- [p. 1030] quences, but not to admit contradictions? Ay, but a person may say, on your admitting a possible hypothesis, "I will drive you upon an impossibility." With such a one as this, shall the wise man never engage, but avoid all argument and conversation with him? And yet who beside the wise man is capable of treating an argument, or who beside is sagacious in reasoning, and incapable of being deceived and imposed on by sophistry? Or will he indeed engage, but without regarding whether he behaves rashly and heedlessly in the argument? Yet how, then, can he be wise, as we are supposing him? and without some such exercise and preparation, how can he hold his own? If this could be shown, then indeed all these forms of reasoning would be superfluous and absurd, and unconnected with our idea of the virtuous man.

Why, then, are we still indolent, and slothful, and sluggish, seeking pretences of avoiding labor? Shall we not be watchful to render reason itself accurate? "But suppose, after all, I should make a mistake in these points, - it is not as if I had killed my father." O slavish man, in this case you had no father to kill. but the only fault that you could commit in this instance, you have committed. This very thing I myself said to Rufus when he reproved me for not finding the weak point in some syllogism. "Why," said I, "have I burnt the capitol then?" "Slave !" answered he, "was the thing here involved the capitol? Or are there no other faults but burning the capitol, or [p. 1031] killing a father?" And is it no fault to treat rashly, and vainly, and heedlessly, the things which pass before our eyes, - not to comprehend a reason, nor a demonstration, nor a sophism; nor, in short, to see what is strong in reasoning and what is weak? Is there nothing wrong in this?

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