Handbook of the History of Logic: - Fordham University Faculty

The Latin Tradition of Logic to 1100 11
In commenting On Interpretation, Boethius again turned to Porphyry, especially
in the second, more advanced commentary [Boethius, 1880] (the first commentary
[Boethius, 1877] was designed just as an aid for beginners to a literal understanding
of the text). He says so himself [Boethius, 1877, 7:5-9], and it seems very likely
that the very influential ideas on semantics and modality he puts forward were
developed by Porphyry in his detailed commentary, now lost.
At the beginning of On Interpretation, Aristotle says (to translate Boethius’s
Latin version literally):
The things therefore which are in the utterance (in voce) are the marks
(notae) of the passions that are in the mind, and the things that are
written of those that are in the utterance. And just as the letters are
not the same for all, so the utterances are not the same; but what they
are primarily signs of, the passions of the mind, are the same for all,
and the things too, of which these are likenesses, are the same. [16a1-8;
Aristotle, 1965, 5:3-9; cf. Magee, 1989, 21-34]
As the commentary as well as the translation shows, Boethius takes Aristotle to
be presenting a semantics which is in many ways a mental language theory. The
‘passions of the mind’ are the words of this language which, unlike written and
spoken languages, is common to all humans, and these passions are in some way
likenesses of objects in the world.
To an extent, this is indeed Boethius’s approach. He speaks explicitly of mental
discourse (oratio) [Boethius, 1880, 30], and he believes that the thoughts that
are its simple terms are combined into complex thoughts that are true or false.
There is, however, an important difference between Boethius’s thinking and a
straightforward theory of this sort. When I utter ‘dog’ and you utter ‘dog’, we
are speaking the same word in the sense that utterances are tokens of the same
type, in virtue of a physical resemblance between the sounds we produce, which
a native speaker would judge to be close enough to take us as uttering the same
word. What about my mental concept of dog and your one? For Boethius, they
can be called the same just because they both [Boethius, 1880, 21:18-22] originate
from the same type of animal. We begin from sensory contact with some object
in the world, form a pre-conceptual image in our mind, on which the intellect
works in order to have a thought of it. It seems, therefore, that in Boethian
mental language, in so far as it is a language, the individual words (‘dog’, ‘cat’,
‘human’) are not imposed on objects, as in a natural language, but derive from
them causally.
When he comes to Chapter 9 of On Interpretation, Boethius has to give his
reading of the much debated passage on future contingents. Earlier (17a1-4) Aristotle
had asserted the principal of bivalence: every proposition is either true or
false. But it seems that, if propositions about future events are true, or are false,
then no future events will be contingent. Suppose p states that a certain event E
will happen tomorrow. If p is true, it seems that E must happen, and if p is false, it
seems that E cannot happen, and so, whether p is true or false, E will not be con-