ERROR AND FALLACIES 319 



reasoners with intent to deceive. Some theory is put forward as a thesis to be 

 established the extreme evolution hypothesis, for instance, including abio- 

 genesis ; or the theory of transformation of species by &quot; natural selection &quot; ; or 

 the view that all religious belief originated in a primitive feeling of fear which per 

 sonified the forces of nature ; or the doctrine that the known universe is purely 

 mechanical, belief in free-will and in purpose or design in nature being an 

 illusion of the mind ; or the agnostic attitude that miracles, revelation, the 

 supernatural, are all alike impossible. . . . The advocate describes and ex 

 pounds his theory ; interprets relevant facts in the light of it ; gets his reader 

 around gradually to look at these provisionally from his own point of view ; 

 shows as plausibly as possible how the facts may be seen to fit in with his 

 theory, or to corroborate it ; insists on reading the facts through the theory, on 

 describing and, so, colouring these in terms of the theory ; substitutes, as far 

 as may be, for the facts themselves, the interpretations he has given them from 

 the theory ; then ventures to show how what he calls the facts (thus coloured, 

 interpreted, manipulated, as they have been) are inconsistent with any other 

 view, and will admit of no other explanation than his own ; and so insinuates 

 the conclusion that the theory advocated is the tiue one. The serious student 

 of religious, philosophical, and scientific literature, who happens to have culti 

 vated the faculty of thinking logically for himself, and of testing what he is asked 

 to accept, will be amazed at the facility and frequency with which writers 

 deceive themselves, or their readers, or both, with pages, or chapters, or even 

 volumes, of such solemn question-begging argumentation. It is not that such 

 writers naively believe, or make believe, that an hypothesis must be true merely 

 because it can give a plausible explanation of the facts. Rather they try to per 

 suade themselves and their readers to look at the facts only through the coloured 

 glass of the hypothesis, and, by such means, to believe that there is no other way 

 in which the facts can be intelligibly apprehended or explained. The^/z/20 

 principii is committed by gratuitously interpreting all the facts only in the light 

 of the preconceived theory. The whole process may also be regarded as an 

 illustration of the fallacy of the consequent : arguing from the truth of the 

 consequent to the truth of the antecedent. 



When the fallacy of petitio principii is committed in a single 

 step of inference, it is called the hysteronproteron (vcrrepov irporepov). 

 It is usually concealed by the use of synonyms. Sometimes the 

 judgment, expressed in abstract terms, is given as a reason for itself 

 in concrete terms : &quot; Opium induces sleep because it has a soporific 

 quality &quot;. Sometimes the fallacy is committed by a single &quot; ques 

 tion-begging epithet&quot; generally either laudatory or condemna 

 tory: as when, to prove that some new measure ought to be re 

 sisted, we call it an innovation, or contend that it would call 

 into question an irrevocable law. The hysteron proteron may be 

 expressed symbolically by the syllogism, &quot; M is P ; S is M ; . . S 

 is P&quot; where M is a synonym for S, or for P : the syllogism would 

 then read &quot;S isP; S is S ; .-. S is P&quot; or &quot; P is P ; S is P ; .: S 

 is P&quot; ; .thus showing one premiss as a tautology and the other as 



