490 FALLACIES. 



State of society. If examples are wanted, almost every historical work, 

 until a very recent period, abounded in them. The same may be said 

 of those who generalize empirically from the people of their owti 

 country to the people of other countries, as if human beings felt, 

 judged, and acted, everywhere in the same manner. 



§ 5. In the foregoing instances, the distinction is confounded between 

 empirical laws, which express merely the customary order of the suc- 

 cession of effects, and the laws of causation on which the effects depend. 

 There may, however, be incorrect generalization when this mistake 

 is not committed ; when the investigation takes its proper direction, 

 that of causes, and the result erroneously obtained purports to be a 

 really causal law. 



The most vulgar form of this fallacy is that which is commonly called 

 post hoc, ergo propter hoc, or cum hoc, ergo propter hoc. As when it is 

 infeiTed that England owes her industrial preeminence to her restric- 

 tions on commerce : as when the old school of financiers, and I am 

 sorry to add, Coleridge, maintained that the national debt was one of 

 the causes of the national prosperity : as when the excellence of the 

 Church, of the Houses of Lords and Commons, of the procedure of 

 the law courts, &c., are inferred from the mere fact that the country 

 has prospered under them. In these and similar cases, if it can be 

 rendered probable by other evidence that the supposed causes have 

 some tendency to produce the effect ascribed to them, the fact of its 

 having been produced, though only in one instance, is of some value 

 as a verification by specific experience : but in itself it goes scarcely 

 any way at all towards establishing such a tendency, since, admitting 

 the effect, a hundred other antecedents could show an equally strong 

 title oi that kind to be considered as the cause. 



In these examples we see bad generalization a posteriori, or empir- 

 icism properly so called : causation infeiTed from casual conjunction, 

 without either due elimination, or any presumption arising from known 

 properties of the supposed agent. But bad generalization a j^riori is 

 fully as common ; which is properly called false theory ; conclusions 

 drawn, by way of deduction, from properties of some one agent which 

 is known or supposed to be present, all other coexisting agents being 

 overlooked. As the former is the error of sheer ignorance, so the 

 latter is especially that of instructed minds ; and is mainly committed 

 in attempting to explain complicated phenomena by a simpler theory 

 than their nature admits of As when one school of physicians sought 

 for the universal principle of all disease in " lentor and morbid viscid- 

 ity of the blood," and imputing most bodily derangements to mechan- 

 ical obstructions, thought to cure them by mechanical remedies ;* while 

 another, the chemical school, " acknowledged no source of disease but 

 the presence of some hostile acid or alkali, or some deranged con- 



* " Thus Fourcroy," says Dr. Paris, "explained the operation of mercury by its specific 

 gravity, and the advocates of this doctrine favored the general introduction of the prepara- 

 tions of iron, especially in schirrus of the spleen or liver, upon the same hypothetical prin- 

 ciple ; for, say they, whatever is most forcible in removing the obstruction must be the 

 most proper instrument of cure ; such is steel, which, besides the attenuating power with 

 which it is furnished, has still a greater force in this case from the gravity of its particles, 

 which, being seven times specifically heavier than any vegetable, acts in proportion with 

 a stronger impulse, and therefore is a more powerful deobstruent. This may be taken as a 

 epecinien of the style in which these mechanical physicians reasoned and practised." 

 t'harmacologia, pp. 38-9. 



