182 INDUCTION. 



cessive expressions for the colligation of observed facts, or, in other 

 words, successive descriptions of a phenomenon as a v^^hole, w^hich has 

 been observed only in parts, may, though conflicting, be all correct as 

 far as they go. But it would surely be absurd to assert this of con- 

 flicting inductions. 



The jihilosojjhic study of facts may be undertaken for three dif- 

 ferent purposes : the simple description of the facts ; their explana- 

 tion ; or their prediction : meaning by prediction, the determination 

 of the conditions under which similar facts may be expected again to 

 occur. To the first of these three operations the name of Induction 

 does not properly belong : to the other • two it does. Now, Mr. 

 Whewell's observation is true of the first alone. Considered as a 

 mere description, the circular theory of the heavenly motions repre- 

 sents perfectly well their general features ; and by adding epicycles 

 without limit, those inotions, even as now known to us, might be 

 expressed with any degree of accuracy that might be required. The 

 only real advantage of the elliptical theory, as a mere description, 

 would be its simplicity, and the consequent facility of conceiving it 

 and reasoning about it : for it would not really be more true than the 

 other. Different descriptions, therefore, may be all true : but not, 

 surely, different explanations. The doctrine that the heavenly bodies 

 moved by a virtue inherent in their celestial nature ; the doctrine that 

 they were moved by impact, (which led to the hypothesis of vortices 

 as the only impelling force capable of whirling bodies in circles,) and 

 the Newtonian doctrine, that they are moved by the composition of a 

 centripetal with an original projectile force ; all these are explana- 

 tions, collected by real induction from supposed parallel cases ; and 

 they were all successively received by philosophers, as scientific 

 truths on the subject of the heavenly bodies. Can it be said of 

 these, as we said of the different descriptions, that they are all true 

 as far as they gol Is it not clear that one only can be true in any 

 degree, and the other two must be altogether false 1 So much for 

 explanations : let us now compare different predictions : the first, 

 that eclipses will occur whenever one planet or satellite is so situated 

 as to cast its shadow upon another ; the second, that they will occur 

 whenever some great calamity is impending over mankind. Do 

 these two doctrines only differ in the degree of their truth, as ex- 

 pressing real facts with unequal degrees of accuracy] Assuredly 

 the one is true, and the other absolutely false. 



In every way, therefore, it is evident that when Mr. Whewell 

 explains induction as the colligation of facts by means of appro- 

 priate conceptions, that is, conceptions which will really express 

 them, he confounds mere description of the observed facts with in- 

 ference from those facts, and ascribes to the latter what is a char- 

 acteristic property of the former. 



There is, however, between Colligation and Induction, a real 

 correlation, which it is important to conceive coixectly. Colligation 

 is not always induction; but induction is always colligation. The 

 assertion that the planets move in ellipses, was but a mode of rep- 

 resenting observed facts ; it was but a colligation ; while the assertion 

 that . they are drawn, or tend, towards the sun, was the statement 

 of a new fact, inferred by induction. But the induction, once made, 

 accomplishes the purposes of colligation likewise. It brings the saui© 



