Handbook of the History of Logic: - Fordham University Faculty

Relational Logic of Juan Caramuel 653
to” (obligation), rather than “must” (necessity), with the corresponding possum,
“can”, taken as permission. Caramuel also seems to be using “must” in the same
context: “it is necessary that I do”, but he does not differentiate its usage from
obligation (“should”). This could be understood as non-deontic necessity or compulsion
opposed to ability (see below). So Caramuel discusses “should (do)”, “can
(do)” and “must (do)” (debeo facere; possum facere; necesse est, ut faciam), focusing
on “should” whose analysis is the same as above. “Facere” (“to do”) makes
explicit that the meaning has to do with human action in contrast to “esse” (“to
be”) used in the examples in “Moral or Political Logic”, where the meaning was
“real”, i.e. metaphysical and physical. The “can” of ability clearly re-surfaces in
Caramuel’s discussion of the relationship between “can” and “should”, or, more
precisely, the inference from “can” to “should”. Caramuel admits this inference
on analogy with the inference from possibility to actuality in necessary matter
(i.e. some necessary connection between the subject and the predicate is possibly
true, therefore, it is true). He admits the argument from the existence of a certain
norm obliging a particular person in conjunction with the ability of this person to
obey the norm to the conclusion that this person should obey the norm. It is clear
that Caramuel understands “can” in the sense of the absence of some hindering
conditions, in the non-deontic sense of ability, not in the sense of permission that
could stand for non debeo non facere. Hence, the inference he has in mind is an
altogether different inference from the immediate illegitimate inference from permission
to obligation. To put it in a nutshell, Caramuel explicitly distinguishes
between real modes and modes having to do with human action, arguably not
discriminating within the latter group, at least not explicitly, between the deontic
modes of permission and obligation on one hand and ability and compulsion on the
other. Consequently, he does not discuss the interrelations among these modes.
In the same work Caramuel analyzes the epistemic mode of knowledge (scio)
and the mode of willing (volo). Both are treated on a par with the universal
affirmative, and again the opposing forms of modals within the logical square are
formulated using negation in the same way as with debeo (“should” or “must”)
above. 27
And once again, there follows the analysis of modes having to do with evidence
and probability. 28 In relation to probability, the oppositions examined hold between
different degrees of probability, and thus they really concern the respective
quantifiers used: mere, magis, minus, aeque. It is clear that the latter three quantifiers
are relational in the sense of essentially involving comparison between probable
propositions. The examination of comparative degrees of probability, and
probability in general, amounts to the logical background of Caramuel’s moraltheological
theory, namely that of probabilism, opposing probabiliorism. According
to the latter, out of two competing moral norms in a particular situation of
moral choice, in the absence of proof of either of the two, one is to opt for the
more probable. Caramuel disagrees: one is morally justified to opt for either of
27 Ibid., p. 58.
28 Ibid., art. III, p. 59-61.