CATEGORICAL JUDGMENTS AND PROPOSITIONS 259 



sometimes even makes the latter impossible. For example, the 

 first law of motion, &quot; Every body not compelled by impressed forces 

 to change its state, continues in its state of rest, or of uniform motion 

 in a straight line&quot; makes a statement about a condition of 

 things that is believed never to have been realized. Similarly, 

 a rule or direction laid down in such terms as &quot; All trespassers 

 are prosecuted&quot; does not imply the existence of its subject. 

 Again, assertions about future events, e.g. &quot; Those who pass this 

 examination will be eligible&quot; carry no necessary implication that 

 the subject exists. 



From those examples we see that the assertoric categorical 

 form, All S is P, does not necessarily imply the existence of its 

 subject, though perhaps it carries this implication (or assumption) 

 oftener than not. Dr. Venn emphasizes the consideration that a 

 single-worded term, standing as subject of a proposition, furnishes 

 a very strong presumption that the subject exists : because &quot; man 

 has something more pressing to do with his vocal organs and 

 inventive powers than to impose names upon objects which he 

 merely contemplates as possible &quot; ; * whereas universals with 

 many-worded terms as subjects will carry no such strong presump 

 tion, but will be found rather to suggest a doubt about the existence 

 of their subjects. These, he points out, are oftener, more easily, 

 and certainly more appropriately, expressed in the hypothetical \\\ax\ 

 in the categorical form on account of this very doubt about the 

 real existence or occurrence of their subjects (cf. 134 infra). 

 This is true even of many categoricals with simple-worded terms. 

 But though the hypothetical may be the more appropriate form 

 for all such, it is no less true that the assertoric categorical, 5 a P, 

 is used to express them, and that, therefore, this form cannot be 

 interpreted as necessarily implying the existence of its subject : 

 the Law of Parsimony forbids us to read any more into a 

 prepositional form than the least amount of meaning it may 

 express. 



What has been said about the universal affirmative applies 

 equally to the universal negative : except that the latter is even 

 more frequently used without any implication of existence. For 

 example : &quot; A planet moving in a hyperbolic orbit can never return 

 to any position it once occupied&quot; &quot; No unicorns have ever been 

 seen &quot; (the universe referred to being the visible, material universe), 



1 Empirical Logic , pp. 258 sqq. 



17 



