166 THE SCIENCE OF LOGIC. 



It is often not easy in practice to distinguish between meaning 

 and implication ; and hence, in reducing ordinary statements to 

 logical form, i.e. to some one or other of the recognized preposi 

 tional forms, or in transferring a proposition from one logical 

 scheme to another, we have sometimes to overstep the limits of 

 mere verbal change, to have recourse to what is really inference, 

 and thus erect into meaning what was originally only an impli 

 cation. 1 Logic postulates the right of mere verbal transformation, 

 the right to vary, as we find it necessary, the mode or form of 

 expression, so long as we do not interfere with the meaning of the 

 judgment expressed. Hence, the legitimacy of any change of 

 wording which involves inference which puts into the meaning 

 of the new form what was only an implication of the old 

 must be determined by reference to the ordinary logical canons 

 of inference. 



JOSEPH, Logic, chap. vii. VENN, Empirical Logic, chap. viii. MELLONE, 

 Introductory Text-Book of Logic, pp. 369 sqq. MERCIER, Logique, pp. 

 131 sqq. MAHER, Psychology, chap. xv. KEYNES, Formal Logic, pt. ii., 

 chap. i. 



be a question of interpretation whether a shall be included in. meaning, b thus be 

 coming an implication, or whether b shall be included in meaning, a becoming an 

 implication.&quot; 



&quot;A failure to recognize what is really the point at issue in a case like this has 

 sometimes caused discussions to take a wrong turn. Thus the question is raised 

 whether the import of the proposition All S is P is that the class S is included in 

 the class P, or that the set of attributes S is invariably accompanied by the set of 

 attributes P ; and these are regarded as antagonistic theories. If the implications of 

 a proposition are regarded as part of its import, then the proposition may be said to 

 import both these things. But it by import of a proposition we intend to signify its 

 meaning only, then we may adopt an interpretation that will make either of them 

 (but not both) part of its import, or our interpretation may be such that the proposi 

 tion imports neither of them.&quot; KEYNES, op. cit., p. 71. 



1 Cf. KEYNES, op. cit., pp. 422-3. 



