|Sažetak (engleski)|| |
This dissertation has two main points. First, Aristotle’s logic enables sound conclusions even in
the language with empty terms. Second, the paradox of nonexistence is not a threat to Aristotle’s
metaphysics. These two points are interconnected. I show that deductive rules in Aristotle’s logic
are sound with respect to dictum de omni et de nullo and/or logical square of opposition as a kind
of “semantical model”. Truth-conditions of various sentences in Aristotle’s logic, derived
from dictum and “modeled by square”, enable sound applications of Aristotle’s syllogistic rules
on language with empty terms. The key feature of the proposed truth-conditions is the existential
import of affirmative sentences. Proposed truth-conditions, however, are dubious and potentially
fallacious from the contemporary point of view. Namely, if every affirmative sentence carries
some ontological commitment, then sentences like ‘Chimaera is a fiction of a poet’ or ‘Achilles is
non-being’ will ontologically commit us that there are (in Quinean sense) non-existent beings.
Naturally, we are not inclined to accept that there exists something that does not exist. Therefore,
my first point brings a burden that has to be explained through the second point.
The resolution of this puzzle can be summarized as follows. Aristotle would be willing to
agree with many contemporary philosophers that existence is not a first-order predicate. The
disagreement arises in Aristotle’s insistence that we could not know that something exists unless
we know what it is. This statement has two layers. First, for a claim that x exists it is required that
we know that x is some determinate being, i.e. an instance of some kind, F or G. Second, the
sentence ‘x is F’ should be further explained in the hylomorphic analysis. According to Aristotle,
the form of a thing is the cause and principle in virtue of which this thing could be recognized as
something, i.e. as an instance of a kind F, and thus, as F thing. The contemporary conception of
existential commitment is to some extent applicable in Aristotle’s case. After all, when Aristotle
says that x is F, he is saying that being F is predicated. At this point it is crucial to understand
that the existence of x is a consequence of predication of being F. Existential commitment, I
conclude, follows from predication of being according to the categorical scheme. Sentences like
‘Chimaera is a fiction of a poet’ or ‘Achilles is non-being’ are not affirmative predications with
respect to categorical scheme, so contemporary worries about the paradox of non-existence
vanish. Precisely such kind of sentences in the medieval period inspired discussion about esse
intentionale and entia rationis for which our contemporary worries about extra-mental and extra-linguistic existential commitments are not in question at all. Since ‘being’ is not a first-order
predicate – and we may add ‘(not) fictitious’, ‘(not) existent’, ‘(not) imaginary’, etc. – affirmative
predications in Aristotle’s logic can carry some existential commitment without the burden of the
paradox of non-existence.
On top of that, Aristotle’s peculiar profile of metaphysical investigation enables us also to
recognize contraries as “ontological furniture of the world”. This fact provides the foundation for
logical law of contrary pair of sentences which is unrecognizable in contemporary philosophy.
Proposed truth-conditions, thus, ultimately spring out of Aristotle’s metaphysics. Nevertheless,
some die-hard Quinean metaphysicist might not be persuaded into the core principles of
Aristotelian metaphysics, but this disagreement belongs to second-level discussions. The paradox
of non-existence, however, is not Aristotle’s crimen on first-level metaphysics.