Handbook of the History of Logic: - Fordham University Faculty

602 Mikko Yrjönsuuri
inferences [Buridan, 2001, 957]. But now, does the existence of the consequence
not guarantee the existence of its antecedent and thereby also the existence of the
proposition ‘a man exists’? Yes and no. Whenever the reasoning is evaluated, the
antecedent exists, but as Buridan shows, to be valid the consequence should hold
also for situations in which it does not exist. This is a distinction Buridan spends
some time to clarify, though we can leave it obscure in respect to our limited
purposes. 30
One further sophism, the fourth one in the set, deserves attention before we
go to Buridan’s treatment of insolubles proper. This sophism still concerns the
attribution of truth values. Suppose you say,
I say that a man is a donkey
Do you now utter a truth or a falsehood? Buridan’s answer is: a truth, literally
speaking. For you indeed say the words ‘a man is a donkey’, and your claim is
that you say those words, and no more. As supporting his claim, Buridan cites
the Psalmist saying “the fool hath said in his heart, there is no God.” As Buridan
notes, this does not commit the Psalmist to the proposition ‘there is no God’ and
indeed this proposition is not in the Psalm as a proposition, but only as a part of
a proposition [Buridan, 2001, 960].
But now, if you say,
‘Man is an animal’ is true,
doesn’t this analysis make the sentence false since here ‘man is an animal’ is not
a proposition? It is just the subject term of a proposition, and as such it cannot
be ascribed a truth value. Buridan accepts [Buridan, 2001, 960–961]. In his view
there is a reading of this sentence that indeed makes it false. For an appropriate
evaluation one needs to know what the subject of the proposition, i.e. ‘man is an
animal’ is taken to supposit for. If you are there referring to another linguistic
structure, similar to the one you mention but used as a proposition, then your
claim may be true. But if you intend your claim to be about the set of words you
utter as the subject in this utterance, then the claim is false for the very same
reason as ‘I say that a man is a donkey’ is true in the sophism.
It seems that Buridan’s idea in structuring his work is that these sophisms
provide exercise and make certain issues clearer before he goes to the genuine
paradoxes of self-reference. This takes place as the seventh sophism, where Buridan
even gives his general solution to the insolubilia [Buridan, 2001, 965–971]. His
paradigm version of the paradox assumes the case that all true propositions have
been annihilated but false ones remain in existence. Then Socrates utters
‘Every proposition is false’,
30 It seems that Buridan distinguishes between validity and truth of a consequence so that
an existing consequence (nowadays called ’conditional’) is true if and only if the consequence
(nowadays called ’inference’) from the antecedent to the consequent is valid. Thus, for validity,
the conditional need not be formulated, but for asserting the validity one needs to make a claim,
a conditional proposition needs to be actually formulated. See [King, 2001].