|MENTAL EVOLUTION AND NECESSARY TRUTHS.|
I AM not about to continue a controversy which I regret having been provoked into by the misrepresentations of one who ignored the contents of works he professed to review. Reply and rejoinder may go on endlessly. I could not, to much purpose, argue with Mr. Hayward, who, instead of taking such unconsciously-formed preconceptions as those resulting from the infinite experiences of muscular tensions and their effects, proposes to exemplify unconsciously-formed preconceptions by a consciously-formed hypothesis concerning the relation between weight and motion. Nor should I care to discuss any question with my new anonymous assailant; who, when certain examples given show the "exact quantitative relations" spoken of to be those of direct proportion, describes me as "intensely unmathematical" because I subsequently use the more general expression as equivalent to the more special—which, in the case in question, it is.
The first of my objects in now writing is to remind "some by-standers, who may from their antecedents be presumed competent to judge," that the essential question is not a mathematical one, but a logical and psychological one, in respect of which I am not aware that senior wranglers, as such, can claim any special competence. Further, even admitting the assumption that the question is mathematical, I have to warn the reader that he will be much misled if he infers that there are not "some by-standers who may from their antecedents be presumed" more "competent to judge," who concur in the opinion that the laws of motion cannot be demonstrated experimentally.
My second object is to inclose, for publication in Nature, a passage now standing in type to be added to future impressions of "First Principles" in further elucidation of necessary truths, and our apprehensions of them:
"The consciousness of logical necessity is the consciousness that a certain conclusion is implicitly contained in certain premises explicitly stated. If, contrasting a young child and an adult, we see that this consciousness of logical necessity, absent from the one, is present in the other, we are taught that there is a growing up to the recognition
- [The article published last month, to which we gave the title of "Punishing a Senior Wrangler," was issued by Mr. Spencer in a pamphlet as a part of his "Replies to Criticism." It led to a running fight in the columns of Nature, which we have not printed. A second "Senior Wrangler" having come to the rescue of the first, with assurances of his "sympathy," and R. B. Hayward having pitched in, Mr. Spencer sends the above communication to Nature, which we reproduce, because of the permanent interest of his argument.—Ed.]