314 Modality. [CHAP. xm. 



as was pointed out in an earlier chapter, every one recog 

 nizes a great variety of modal forms, such as likely, very 

 likely, almost certainly/ and so on almost without limit in 

 each direction. It was doubtless supposed that, by neglect 

 ing to make use of technical equivalents for some of these 

 forms, we should lose our logical control over certain possible 

 kinds of inference, and so far fall short even of the precision 

 of ordinary thought. 



With regard to such additional forms, it appears to me 

 that all those which have been introduced by writers who- 

 were uninfluenced by the Theory of Probability, have done 

 little else than create additional confusion, as such writers do- 

 not attempt to marshal their terms in order, or to ascertain 

 their mutual relations. Omitting, of course, forms obviously 

 of material modality, we have already mentioned the true 

 and the false ; the probable, the supposed, and the certain. 

 These subdivisions seem to have reached their climax at a 

 very early stage in Occam (Prantl, III. 380), who held that a, 

 proposition might be modally affected by being vera, scita,. 

 falsa, ignota, scrip ta, prolata, concepta, credita, opinata, du- 

 bitata. 



20. Since the growth of the science of Probability, 

 logicians have had better opportunities of knowing what 

 they had to aim at ; and, though it cannot be said that their 

 attempts have been really successful, these are at any rate a 

 decided improvement upon those of their predecessors. Dr 

 Thomson 1 , for instance, gives a nine-fold division. He says 

 that, arranging the degrees of modality in an ascending 

 scale, we find that a judgment may be either possible, 

 doubtful, probable, morally certain for the thinker himself, 

 morally certain for a class or school, morally certain for all, 

 physically certain with a limit, physically certain without 

 1 Laws of Thought, 118. 



