MOULTON ON SPENCER'S "FIRST PRINCIPLES" 279 



The writer of the Review was the Senior Wrangler of 1 868, who is now the 

 Right Honourable Sir John Fletcher Moulton, one of the Lord Justices of 

 England. His strictures were of course replied to by Spencer, who, as is 

 usual in such controversies, passed by without remark the most condemnatory 

 parts. It is interesting to note, however, that in the next edition of the First 

 Principles readers will look in vain for certain of the most striking of the 

 quotations introduced by the Reviewer in his exposure of Spencer's 

 ignorance of physical principles. These sentences were silently removed 

 without a word of explanation, presumably on the principle elsewhere 

 enunciated by Spencer when in reply to other criticisms he remarked 1 

 " Though still regarding the statement I had actually made as valid, I 

 concluded it would be best to remove the stumbling block out of the way of 

 future readers." 



At the close of his " Replies to Criticisms " in the Fortnightly Review, 

 Herbert Spencer endeavoured to turn the keen edge of the British Quarterly 

 Reviewer's damaging attack; and in February 1874 this portion with 

 additions was issued as a pamphlet entitled " Mr Herbert Spencer and the 

 British Quarterly Review." To anyone acquainted with physical principles 

 the reply is a revelation of how a man with a marvellous power of assimilating 

 knowledge and a unique gift of exposition can fail in understanding not 

 merely the criticism but also the facts on which the criticism is based. 

 For example Herbert Spencer's conception of what is meant by the adiabatic 

 condensation and rarefaction of air through which sound is passing is not 

 merely crude and incomplete it is profoundly erroneous. 



One of Spencer's main positions was that "our cognition of the Per- 

 sistence of Force is a priori," against which the Reviewer quoted from Tail's 

 Thermodynamics to the effect that 



" Natural Philosophy is an experimental, and not an intuitive science. No a priori 

 reasoning can conduct us demonstratively to a single physical truth." 



Spencer believed he found a discrepancy between this statement and the 

 following sentence from Thomson and Tail's Treatise on Natural Philosophy : 



"As we shall show in our chapter on Experience, physical axioms are axiomatic 

 to those only who have sufficient knowledge of the action of physical causes to enable 

 them to see at once their necessary truth." 



1 See Appendix to First Principles dealing with Criticisms, p. 586, issued as a separate 

 pamphlet in July 1880. 



