354 NECESSARY TRUTH 



by common sense in so many ways, and if the tests are conducted 

 with sufficient care, I so invariably find the evidence consistent 

 with itself, that it seems to me highly probable that my assump- 

 tions are correct. As to the actual nature of the reality which I 

 think my mind symbolizes, I make no guess. I use the word 

 * matter,' but only as a convenient name for a something of which 

 I have no immediate knowledge. Since I suppose that my mind 

 symbolizes reality, I suppose also that the uniformities which I 

 detect in nature are due to a uniformity of causation which 

 depends on the qualities and relations of material objects, not on 

 a mere invariable and utterly unaccountable succession of mental 

 happenings, which is all that the idealist has a right to postulate. 

 Therefore, though I do not know the whole circle of causation, 

 but only a little part of it, yet, within the narrow limits of 

 my knowledge, the universe appears to be comprehensible, and 

 I am able to say that I understand and can explain. I am, 

 then, in one respect, an idealist, and in another a materialist. 

 I am an idealist in that I know I know my feelings, but 

 nothing else. I am a materialist in that I believe my feelings 

 symbolize reality. My attitude differs from the common sense of 

 everyday life and of science (which accepts appearances for what 

 they seem to be) in this matter of symbolism. I suppose I am 

 like a man who is deaf, and knows that he is deaf, but who can 

 read. I am not like a deaf man, who, being able to read, supposes 

 that he can hear, or, at the other, the idealist, extreme, like one 

 who, being able to read, supposes he can neither hear nor read. 



593. Granting the existence of material objects, then evidently 

 there are two distinct ways in which we may classify facts, 

 and so create science. On the one hand, we may arrange our 

 data accordingly as the objects we have under consideration 

 have, or have not, properties, or, as they are termed in biology, 

 4 characters,' in common. Thus, since a man possesses certain 

 characters in common with other living beings, we classify him 

 as an animal, a vertebrate, a mammal, and so on. In this way 

 systematic zoology, botany, and anatomy have been developed. 

 Here the mental faculties we employ are principally observation, 

 recollection, comparison, and the like. On the other hand, we 

 may arrange our facts in chains of causation. This is the 

 method adopted in mathematics, physics, to a great extent in 

 astronomy, and in biology when we discuss problems of heredity 

 and evolution. Here, regarding the properties of objects as causes 

 or effects, we proceed principally by formulating hypotheses, which 



