304 Modality. [CHAP. xin. 



both in our premises and in our conclusion. Such a plan 

 therefore for treating modality, as the one under discussion, 

 is just as much a banishment of it from the field of real 

 logical enquiry, as if we had determined avowedly to reject it 

 from consideration. 



9. Before proceeding to a discussion of the various 

 ways in which modality may be treated by those who admit 

 it into logic, something must be said to clear up a possi 

 ble source of confusion in this part of the subject. In the 

 cases with which we have hitherto been mostly concerned, 

 in the earlier chapters of this work, the characteristic of 

 modality (for in this chapter we may with propriety use this 

 logical term) has generally been found in singular and par 

 ticular propositions. It presented itself when we had to 

 judge of individual cases from a knowledge of the average, 

 and was an expression of the fact that the proposition re 

 lating to these individuals referred to a portion only of the 

 whole class from which the average was taken. Given that 

 of men of fifty-five, three out of five will die in the course of 

 twenty years, we have had to do with propositions of the 

 vague form, It is probable that AB (of that age) will die, 

 or of the more precise form, It is three to two that AB will 

 die, within the specified time. Here the modal proposition 

 naturally presents itself in the form of a singular or par 

 ticular proposition. 



10. But when we turn to ordinary logic we may find 

 universal propositions spoken of as modal. This must mostly 

 be the case with those which are termed necessary or im 

 possible, but it may also be the case with the probable. We 

 may meet with the form All X is probably F. Adopting 

 the same explanation here as has been throughout adopted in 

 analogous cases, we must say that what is meant by the 

 modality of such a proposition is the proportional number of 



