486 FALLACIES. 



consequent, or that antecedents competent to do this do not exist in 

 nature, we are in no case empowered positively to conclude. 



§ 3. It is next to be remarked that all generalizations which profess, 

 like the theories of Thales, Democritus, and others of the early Greek 

 philosophers, to resolve all things into some one element, or, like many 

 hiodei-n theories, to resolve phenomena radically different into the 

 same, are necessarily false. By radically difterent phenomena I mean 

 impressions on our senses which differ in quality, and not merely in 

 degree. On this subject what appeared necessary was said in the 

 chapter on the Limits to the Explanation of Laws of Nature; but as 

 the fallacy is even in our own times a common one, I shall touch upon 

 it somewhat further in this place. 



When we say that the force which holds the planets in their orbits 

 is resolved into gravity, or that the force which make substances com- 

 bine chemically is resolved into electricity, we assert in the one case 

 what is, and in the other case what might, and probably will ultimately 

 be a legitimate result of induction. In both these cases, motion is 

 resolved into motion. The assertion is, that a case of motion, which 

 was supposed to be special, and to follow a distinct law of its own, 

 conforms to and is included in the general law which regulates another 

 class of motions. But, fi-om these and similar generalizations, counte- 

 nance and currency has been given to attempts to resolve not motion 

 into motion, but heat into motion, light into motion, sensation itself into 

 motion (as in Hartley's doctrine of vibi-ations) ; states of consciousness 

 into states of the nervous system, as in the ruder forms of the materi- 

 alist philosophy; vital phenomena into mechanical or chemical pro- 

 cesses, as in some schools of physiology. 



Now I am far from pretending that it may not be capable of proof, 

 or that it would not be a very important addition to our knowledge if 

 proved, that certain motions in the particles of bodies are among the 

 conditions of the -production of heat or light; that certain assignable 

 physical modifications of the nerves may be among the conditions not 

 only of our sensations or emotions, but even of our thoughts; that cer- 

 tain mechanical and chemical conditions may, in the order of nature, be 

 sufficient to detennine to action the physiological laws of life. All I 

 insist upon, in common with every sober thinker since modem science 

 has been definitively constituted, is, that it shall not be supposed that by 

 proving these things one step would be made towards a real explanation 

 of heat, light, or sensation; or that the generic peculiarity of those 

 phenomena can be in the least degree evaded by any such discoveries, 

 however well established. Let it be shown, for instance, that the 

 most complex series of physical causes and effects succeed one another 

 in the eye and in the brain to produce a sensation of color; rays falling 

 upon the eye, refracted, converging, crossing one another, making an 

 inverted image on the retina, and after this a motion — let it be a 

 vibration or a rush of nervous fluid, or whatever else you are pleased to 

 suppose, along the optic nerve — a propagation of this motion to the 

 brain itself, and as many more different motions as you choose; still, 

 at the end of these motions, there is something which is not a motion, 

 there is a feeling or sensation of color. "VVliatever number of motions 

 we may be able to intei-polate, and whether they be real or imaginary, 

 we shall still find, at the end of the series, a motion antecedent and a color 



