180 DOGMATISM AND EVOLUTION 



in various senses which are by no means always kept distinct. 

 First, it is used to signify an incompleteness of knowledge about 

 a particular event, as when it is said that a certain imagined 

 future event is a possibility but not a certainty. This is equiva 

 lent to saying that so far as is known the event may or may not 

 happen. This obviously is not the sense in which Mill employs 

 the term, nor does the criticism with which we are concerned 

 imply any such understanding of it. Secondly, the term is ap 

 plied to what is regarded as the essential condition of the future 

 existence of a thing. Thus the egg is, or contains, the possibil 

 ity of the chick; that is, the existence of the egg, although not 

 sufficient to determine the future existence of the chick, is never 

 theless regarded as the essential condition of the chick s being. 

 Hence, if one were to assert that the chick s existence is a real 

 possibility, such an assertion must owe its truth to the actual 

 existence of the egg the possibility in other words, must exist 

 as an actuality, Now it is this sense of the term possibility 

 which Mill s critic evidently has in mind, when he contends that 

 the phrase, permanent possibility of sensation, may express all 

 that we know of the nature of the object, but that it must 

 nevertheless exist as an unknown or even unknowable actuality. 

 But is it in precisely this sense that Mill uses possibility ? Let 

 us take the case of the object that is directly perceived, and ask 

 what Mill conceives this present object to be. Obviously its 

 present existence is not the actual sensations we are having; the 

 object, even when directly perceived, is still the possibility of a 

 group of sensations. Mill s statement, that the object is the 

 possibility of sensation, is not analogous to the statement, that 

 the egg is the possibility of the chick; for in the latter case the 

 egg is an existent of the same order as the chick. In the former 

 case, on the contrary, the object is not an existent of the same 

 order as is the sensation it is, as we remarked before, ideal with 

 reference to the sensation, which is real. There is, indeed, an 

 actuality which corresponds to the possibility of the group of 

 sensations; namely, the present sense-experience, whatever it 



