Handbook of the History of Logic: - Fordham University Faculty

606 Mikko Yrjönsuuri
can cross it without his permission. And then Socrates arrives, asking Plato with
insistence to let him cross. Then Plato, getting angry, vows and takes an oath of
the form: ‘Certainly, Socrates, if with your first proposition that you will utter
you say something true, I will let you pass, but certainly if you say something
false, I will throw you in the water’. And then Socrates says to Plato the above
mentioned sophism, namely, ‘You will throw me in the water’. The problem then
is: what should Plato do to keep his promise?”
As a careful, not to say tedious logician, Buridan gives a much fuller analysis
of the sophism than Sancho Panza will do later. In Buridan’s analysis, Socrates’s
sentence concerns a future contingent and therefore, its truth value can be determined
only later, when it will be seen what happens. Thus, refraining from
evaluation does not mean asserting a truth value gap. Further, Plato’s claim is
a conditional one, and there is no necessary connection between the antecedent
and the consequent. In the strict sense, Plato speaks falsely. However, as Buridan
notes, one should rather interpret Plato as giving a promise, which is usually said
to be true when the person keeps his promise. And Plato does not. As a promise,
the utterance is false. Socrates does not fill the condition, because he utters a
proposition that is not yet determinately true or false (though it is, in Buridan’s
view, either true or false). Plato is not able to keep his promise, because through
his utterance Socrates makes Plato’s promise self-reflexive (habens reflectionem
supra se). When it is asked, whether Plato needs to keep his promise, Buridan
answers negatively, just as Sancho Panza will. Plato cannot keep his promise, and
thus he need not. He should not have given a promise vulnerable to paradox.
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