§ 1). “A modal proposition may be stated as a pure one by attaching the mode to one of the terms, and the proposition will in all respects fall under the foregoing rules;… ‘It is probable that all knowledge is useful;’ ‘probably useful’ is here the predicate.” He draws apparently no such distinction as that between the true and false modality referred to in the next note. What is really surprising is that even Hamilton puts the two (the true and the false modality) upon the same footing. “In regard to these [the former] the case is precisely the same; the mode is merely a part of the predicate.” Logic, I. 257.
[3] I allude of course to such examples as ‘A killed B unjustly,’ in which the killing of B by A was sometimes said to be asserted not simply but with a modification. (Hamilton's Logic, I. 256.) It is obvious that the modification in such cases is by rights merely a part of the predicate, there being no formal distinction between ‘A is the killer of B’ and ‘A is the unjust killer of B.’ Indeed some logicians who were too conservative to reject the generic name of modality in this application adopted the common expedient of introducing a specific distinction which did away with its meaning, terming the spurious kind ‘material modality’ and the genuine kind ‘formal modality’. The former included all the cases in which the modification belonged by right either to the predicate or to the subject; the latter was reserved for the cases in which the modification affected the real conjunction of the predicate with the subject. (Keckermann, Systema Logicæ, Lib. II.
ch. 3.) It was, I believe, a common scholastic distinction.
For some account of the dispute as to whether the negative particle was to be considered to belong to the copula or to the predicate, see Hamilton's Logic, I. 253.
[4] He has also given a short discussion of the subject elsewhere (Discussions, Ed. II.
p. 702), in which a somewhat different view is taken. The modes are indeed here admitted into logic, but only in so far as they fall by subdivision under the relation of genus and species, which is of course tantamount to their entire rejection; for they then differ in no essential way from any other examples of that relation.
[5] Letters, Lectures and Reviews, p. 61. Elsewhere in the review (p. 45) he gives what appears to me a somewhat different decision.
[6] It must be remembered that this is not one of the proportional propositions with which we have been concerned in previous chapters: it is meant that there are exactly 21 Ys, of which just 18 are X, not that on the average 18 out of 21 may be so regarded.
[7] I consider however, as I have said further on ([p. 320]), that the treatment in the older logics of Probable syllogisms, and Dialectic syllogisms, came to somewhat the same thing as this, though they looked at the matter from a different point of view, and expressed it in very different language.
[8] The distinction is however by no means entirely neglected. Thus Smiglecius, when discussing the modal affections of certainty and necessity, says, “certitudo ad cognitionem spectat: necessitas vero est in re” (Disputationes; Disp. XIII., Quæst. XII.).