THE DEDUCTIVE METHOD. 207 



live, resources for ascertaiuing the laws of the causes considered sepa- 

 rately, when we have it not in our power to make trial of them in a 

 state of actual separation. The insufficiency of these resources is so 

 glaring that no one can be surprised at the backward- state of the 

 science of physiology ; in which indeed our knowledge of causes is so 

 imperfect, that we can neither ex])lain, nor could, without specilic 

 experience, have predicted many of the facts which are certified to us 

 by the most ordinary observation. Fortunately, wc are much better 

 informed as to the empirical laws of the phenomena, that is, the 

 unifonnities respecting which we cannot yet decide whether they are 

 ■^cases of causation or mere results of it. Not oidy has the order iij 

 ■which the facts of organization and life successively manifest them- 

 selves, from the first genu of existence to death, been found to be uni- 

 foiTn, and veiy accurately ascertainable ; but, moreover, by a great 

 application of the Method of Concomitant Variations to the entire 

 facts of comparative anatomy and physiology, the conditions of or- 

 ganic structure corresponding to each class of functions have been 

 determined with considerable precisiori.* Whether these organic 

 conditions are the whole of the conditions, and whether they be con- 

 ditions at all, or mere collateral effects of some common cause, we are 

 quite ignorant : nor are we ever likely to know, unless we could con- 

 struct an organized body, and Irj whether it would live. 



Under §uch disadvantages do we, in cases of this description, at- 

 tempt the initial, or inductive step, in the application of the Deductive 

 Method to complex phenomena. But such, fortunately, is not the 

 common^ case. In general, the laws of the causes on which the effect 

 depends may be obtained by an induction from comparatively simple 

 instances, or, at the worst, by deduction from the laws of simpler 

 causes so obtained. By simple instances are meant, of course, those 

 in which the action of each calise was not intermixed or interfered 

 with, or not to any gieat extent, by other causes whose laws wcie 

 unknown. And only when the induction which furnished the prem- 

 isses to the Deductive Method rested upon such instances, has the 

 application of such a method to the ascertainment of the laws of a 

 complex effect, been attended with brilliant results. 



§ 2. ^Vhen the lavvs of the causes have been -ascertained, and the 

 first stage of the gi-eat logical operation now under discussion satis- 

 factorily accompKshcd, the second parj, follows; that of determining, 

 from the laws of the causes, what eflect any given combination of those 

 causes will prod'uce. This is a process of calculation, in the wider 

 sense of the term ; and very often involves processes of calculation in 

 the narrowest sense. It is a ratiocination ; and when our knowledge 

 of the causes is so perfect, as to extend to the exact numerical laws 

 which they observe in producing their effects, the ratiocination may 

 reckon among its premisses the theorems of the science of number, in 

 the whole immense extent of that science. Not only are the highest 

 truths of mathematics often required to enable us to compute an effect, 

 the numerical law of which we already know ; but, even by the aid 

 of those highest truths, we can go but a little way. In so simple a 

 case as the celebrated problem of throe bodies gravitating towards one 



♦ This great philosophical operation' has been admirably characterized in the third vol- 

 ume of M. Comte's truly encyclopedical work. 



