238 THE SCIENCE OF LOGIC 



lateral triangles are equiangular &quot; contained in it without any 

 inference. 



Simple Conversion (of E and I). Simple Conversion, as op 

 posed to Conversion by Limitation, is that in which the converse 

 retains the quantity as well as the quality of the convertend. The 

 simple converse is therefore equivalent to the convertend : we may 

 pass back from converse to convertend : no part of the import is 

 lost in either process. 



The E proposition can be converted simply : for it asserts 

 that the attributes connoted by P are to be found in none of the 

 objects denoted by 5, and that therefore none of the objects in 

 which P is found, none of the objects denoted by P, possess the 

 attributes connoted by 6*. In other words it distributes its predicate, 

 P, thus totally separating the things that possess the attribute 

 5 from those that possess the attribute P. If &quot; No squares are 

 circular&quot; then &quot;No squares are any circles&quot; : and hence &quot; No 

 circles are square&quot; or &quot;No circles are (any) squares&quot;. Thus 

 SeP converts simply to PeS. 1 



Similarly, the particular affirmative, StP t which distributes 

 neither of its terms, may be simply converted to PiS, which also 

 distributes neither of its terms. Both propositions are equivalent : 

 we may pass from either to the other without any loss of mean 

 ing : the process is reciprocal. 



The conversion of O is impossible. SoP, if converted, must 

 convert to a negative (by the Rule of Quality] : but the 

 negative will distribute its predicate, which will be S: this, 

 however, is impossible (by the Rule of Quantity) y seeing that 5 

 was not distributed in the convertend, SoP. 



The student should never attempt to convert a proposition 

 without first (i) reducing it to logical form, determining (2) the 

 quantity of the subject, and (3) the quantity of the predicate. 

 And he should remember that the logical copula can be only is 

 (not), or are (not). 



It is easier to convert propositions which have substantives for 

 predicates than those which have adjectives. In converting the 

 latter we must supply the appropriate substantive the next 

 highest genus of the subject or change the adjective into a sub 

 stantive. Thus : All men are mortal Some mortals are men. 

 Verb-predicates must be resolved into the copula and a participle, 



1 Cf. infra, chap, vii., for influence of suppositions regarding existential import 

 on the doctrines of the present chapter. 



