No. 559] DOCTRINES HELD AS VITALISM 



397 



cases essentially a prediction, for it says that if you get 

 one set of experiences, you will have another also. But 

 the prediction is made on the basis of experience already 

 had. It could not he predicted without experience that 

 the union of C, H and in certain proportions will give 

 the characteristic properties of the alcohols. There is 

 no a priori reason that can he given for the appearance, 

 in the first instance, of these characteristics. Yet we can 

 use the experienced fact that they do appear in further 

 prediction or explanation of what occurs under certain 

 conditions. We learn by experience in the alcohol series 

 what effect is produced by adding certain radicals; after 

 this we can predict what effect such addition will have, 

 provided other conditions do not alter the ease. Whether 

 any given set of the other conditions will alter the case 

 can again be determined, in the first instance, only by 

 experience. 



This is certainly typical for the actual process of 

 building up a large part of science. For such parts the 

 fact of special importance here is the one last stated: 

 Whether any given change in the conditions will alter 

 the action can be determined, in the first instance, only 

 by experience. This is exemplified in multitudes of in- 



" critical points." By numerous observations it is de- 

 termined what progressive change in the properties of a 

 substance is made by a certain amount of change in some 

 condition, as temperature. A general law can be de- 

 duced which, since it works regularly so far as observed, 

 would naturally be extended to include changes in parts 

 of the scale not observed. But this would give false re- 

 sults, for at a certain point the characteristics suddenly 

 change, becoming totally diverse from what they were, 

 as in solidifying or vaporizing. Such sudden changes are 

 most marked in chemistry. We have two substances 

 mixed together, as PI and 6. We observe and formulate 

 the changes they undergo as certain conditions are grad- 

 ually changed. But at a certain point in this gradual 



