Principia Ethica
Principia Ethica is a 1903 book by the British philosopher G . E . Moore , in which the author insists on the indefinability of "good" and provides an exposition of the naturalistic fallacy . 
<triplet> Principia Ethica <subj> 1903 <obj> publication date <subj> G. E. Moore <obj> author <triplet> naturalistic fallacy <subj> Principia Ethica <obj> described by source