394. Examine technically the following argument:—
Everyone is either well informed of the facts or already convinced on the subject; no one can be at the same time both already convinced on the subject and amenable to argument: hence it follows that only those who are well informed of the facts are amenable to argument. [J.]
395. Dr Johnson remarked that “a man who sold a penknife was not necessarily an ironmonger.” Against what logical fallacy was this remark directed? [C.]
396. Examine the following arguments, pointing out any fallacies that they contain: 436
(a) The more correct the logic, the more certainly will the conclusion be wrong if the premisses are false. Therefore, where the premisses are wholly uncertain the best logician is the least safe guide.
(b) The spread of education among the lower orders will make them unfit for their work: for it has always had that effect on those among them who happen to have acquired it in previous times.
(c) This pamphlet contains seditious doctrines. The spread of seditious doctrines may be dangerous to the State. Therefore, this pamphlet must be suppressed. [C.]
397. Examine the following arguments:—
(1) A telescope with the eye-piece at one side of the tube is probably a reflector; Lord Rosse’s telescope is a reflector; therefore, Lord Rosse’s telescope probably has the eye-piece at one side of the tube.
(2) Good workmen do not complain of their tools; my pupils do not complain of their tools; therefore, my pupils are probably good workmen.
(3) If, on the one hand, the heathen, through want of better knowledge, cannot help breaking the Ten Commandments, then they do not stand condemned; if, on the other hand, they are condemned, it is for doing that which they well knew was wicked, and which they were well able to refrain from doing; therefore, whatever happens to them, justice is satisfied. [K.]
398. Discuss the nature of the reasoning contained, or apparently intended, in the following sentences:—
It is impossible to prove that persecution is justifiable if you cannot prove that some non-effective measures are justifiable; for no persecution has ever been effective.
This deed may be genuine though it is not stamped, for some unstamped deeds are genuine. [C.]
399. State the following arguments in logical form, and examine their validity:—
(1) Poetry must be either true or false: if the latter, it is misleading; if the former, it is disguised history, and savours of imposture as trying to pass itself off for more than it is. Some philosophers have therefore wisely excluded poetry from the ideal commonwealth. 437
(2) If we never find skins except as the teguments of animals, we may safely conclude that animals cannot exist without skins. If colour cannot exist by itself, it follows that neither can anything that is coloured exist without colour. So if language without thought is unreal, thought without language must also be so.
(3) Had an armistice been beneficial to France and Germany, it would have been agreed upon by those powers; but such has not been the case; it is plain therefore that an armistice would not have been advantageous to either of the belligerents.
(4) If we are marked to die, we are enow
To do our country loss: and, if to live.
The fewer men, the greater share of honour. [O.]
400. Examine logically the following arguments:—
(a) If truthfulness is never found save with scrupulousness, and if truthfulness is incompatible with stupidity, it follows that stupidity and scrupulousness can never be associated.
(b) You say that there is no rule without an exception. I answer that, in that case, what you have just said must have an exception, and so prove that you have contradicted yourself.
(c) Knowledge gives power; consequently, since power is desirable, knowledge is desirable. [L.]
401. Examine the following arguments, stating them in syllogistic form, and pointing out fallacies, if any:—
(a) Some who are truly wise are not learned; but the virtuous alone are truly wise; the learned, therefore, are not always virtuous.
(b) If all the accused were innocent, some at least would have been acquitted; we may infer, then, that none were innocent, since none have been acquitted.
(c) Every statement of fact deserves belief; many statements, not unworthy of belief, are asserted in a manner which is anything but strong; we may infer, therefore, that some statements not strongly asserted are statements of fact.
(d) That many persons who commit errors are blameworthy is proved by numerous instances in which the commission of errors arises from gross carelessness. [M.]
402. Examine technically the following arguments:—
(1) Those who hold that the insane should not be punished ought in consistency to admit also that they should not be threatened; 438 for it is clearly unjust to punish any one without previously threatening him.
(2) If he pleads that he did not steal the goods, why, I ask, did he hide them, as no thief ever fails to do?
(3) Knavery and folly always go together; so, knowing him to be a fool, I distrusted him.
(4) How can you deny that the infliction of pain is justifiable if punishment is sometimes justifiable and yet always involves pain?
(5) If I deny that poverty and virtue are inconsistent, and you deny that they are inseparable, we can at least agree that some poor are virtuous. [V.]
403. Detect the fallacy in the following argument:—
“A vacuum is impossible, for if there is nothing between two bodies they must touch.” [N.]