FALLACIES OF GENERALIZATION. 491 



dition in the chemical composition of the fluid or sohd parts," and 

 conceived, therefore, that " all remedies must act hy producing <lu>m- 

 ical changes in the body. We find Tournefort busily engaged in test- 

 ing every vegetable juice, in order to discover in it some traces of an 

 acid or alkaline ingredient, which might confer upon it medicinal ac- 

 tivity. The fatal errors into which such an hypotlu'sis was liable to 

 betray the practitioner, receive an awful illustration in the history of 

 the memorable fever that raged at Leydenin the year 1699, and which 

 consigned two-thirds of the pojiulation of that city to an untimely 

 gi-ave ; an event which in a great measure depended uj)on the Pro- 

 fessor Sylvius de la Boe, who having just embraced the chemical doc- 

 ti'ines of ^'an Helmont, assigned tlie origin of the distemj)er to a pre- 

 vailing acid, and declared that its cure could alone be eH'ected by the 

 copious administration of absorbent and testaceous medicines."* John 

 Brown, the author of the famous Brunonian Theory, *' generalized dis- 

 eases, and brought all within the compass of two grand clas.ses, those 

 of increased and diminished excitement;" and maintained " that every 

 agent which could operate on the human body was a stimulant, having 

 an identity of action, and dificring only in the degree of its force ; so 

 that according to his views the lancet and the brandy bottle were but 

 the opposite extremes of one and the same class."! 



These aberrations in medical theory have their exact parallels in 

 politics. All the doctrines which ascribe absolute goudn(;ss to partic- 

 ular forms of govemment, particular social arrangements, and even to 

 particular modes of education, without reference to the state of civiliza- 

 tion and the various distinguishing characters of the society for which 

 they are intended, are open to the same objection — that of assuming 

 one class of influencing circumstances to be the paramount rulers of 

 phenomena which depend in an equal or greater degree upon many 

 others. But on these considerations it is the less necessary that wo 

 should now dwell, as they will occupy our attention very largely in 

 the concluding Book. 



§ 6. The last of the modes of ciToneons generalization to which I 

 shall advert, is that to which wo may give the name of False Analogies. 

 This Fallacv stands distinguished from those already treated of by the 

 peculiarity, that it does not even simulate a complete and conclusive 

 induction, but consists in the misapplication of an argument which is 

 at best only admissible as an inconclusive presumption, where real 

 proof is unattainable. 



An argument from analogy, is an inference that what is tnie in a cer- 

 tain case is true in a case known to bo somewhat similar, but not known 

 to be exactly parallel, that is, to be similar in all the material circum- 

 stances. An ol)joct has the property B: another object is not known to 

 have that propeit}', but resembles tlu^ first in a property A, not known to 

 be connected with B; and the conclusion to which the analogy points, 

 is that this object has the property B also. As, fi)r example, that the 

 planets are inhabited because the earth is. The planets resemble tho 

 earth in describing elliptical orbits round the sun, in V)eing attracted 

 by it and by one another, in being spherical, revolving u])on their axes, 

 &c. ; but it is not knoAvn that any of these properties, or all of tliem 



» Pharmacohsia, pp. 39, 10. f id'd., p. 43. 



