NATURE AND NURTURE 75 



perplexity may not be laid to the charge of those metaphysicians 

 and theologians and philosophers who have told him that actions 

 which are mechanical cannot be free, because they are necessary ? 



When we control our visual sensations by shutting our eyes, 



employ physical means, and while one who is thus enabled^ 

 to control some of his mental states by physical means may also 

 be able to use these means or not as he chooses, how can this 

 be evidence that his ability is independent of physical means ? 



Is it necessary to know what the relation between mind and 

 matter is, in order to study mind ? As we know what we mean 

 by a plant, and may study botany, without knowing when or how 

 plants become differentiated from animals, and without knowing any 

 absolute diagnosis of a plant, so, too, may we not study know- 

 ledge, without knowing when or how it becomes differentiated from 

 instinct and impulse and emotion and unperceived cerebration ? 



As we use the words, is knowledge equivalent to response, 

 or to beneficial response, or to the improvement of response, or 

 to response which is immediately controlled? Is it not rather 

 the correction of our judgment and its reduction to exactness ? 

 Whether knowledge is innate or not, does any one believe that 

 our judgment is ever corrected without a "sensible occasion"? 

 May not the amount of this correction be measured by experi- 

 ence ? If what we mean by knowledge is the correction of our 

 judgment under the stimulus of experience, is it not idle to ask 

 whether we may have knowledge without experience, for is not 

 this a contradiction in terms ? If any choose to define knowledge 

 as response, and to thus use the word consistently, no one need 

 object, for words are conventional symbols, which change their 

 meaning continually, although no one who uses common words 

 in an uncommon way, without defining them, can hope to be 

 understood. 



We are told that if the " Lamarckian factors " are in any 

 degree operative at all, their great function "must be that of 

 supplying to natural selection the incipient stages of adaptive 

 modification, in all cases where, but for this agency, there would 

 be nothing of the kind to select"; but unless these "factors'* 

 can be proved to have this function, they are unworthy of con- 

 sideration as a contribution to the history of adaptive modification. 



