Franz Brentano_The True and the Evident.pdf

On the Concept of Truth 5
b) And the paradoxical theses of the Sophists also play upon difficulties bound up with
these early opinions. We have Gorgias denying that anything real can be known, and then
adding that, even if there were anything that could be known, it would be impossible
to communicate the knowledge from one person to another. There is nothing which
corresponds completely to anything other than itself. What is external to me is not in me,
and what is and remains in me, does not pass over into anyone else. Thus truth, as well as
the communication of truth, is impossible. If any of our thoughts can be said to be true,
then, according to Gorgias, everything else can be said to be true. For every thought is
identical with itself as well as different from all other thoughts. But that every thought
should be called true, even when I think of a chariot race on the sea, is an absurdity.
c) Nevertheless, another Sophist comes forth to present the contrary thesis. Protagoras
does not say that all our beliefs are false; he says instead that all our beliefs are true.
Whatever one thinks a thing to be, it is, and whatever one thinks it not to be it is not.
It is easy to see, I think, how Protagoras arrived at this idea. If a belief is true provided
only it corresponds completely with something that exists, then every belief is true, for
every belief is identical with itself. Aristotle also connects this thought with the doctrines of
the Ionic school upon which the contrary thesis of Gorgias depends. Protagoras, who was
a true Sophist, according to the classical portrait (that is to say, the portrait that was drawn
by Plato and Aristotle, and not the one by Grote, who lived somewhat later), now quite
obviously turns the paradox he had come upon into the starting-point of an ingenious game.
The Down-Throwers was the name of the text in which Protagoras defended
his thesis. In it, apparently, blows are being dealt, and threatening objections parried.
To the objection that, if his view were correct, a thing could be said both to be and not
to be at one and the same time, Protagoras seems to have replied that such a consequence
is not absurd; the point just is that the thing is for one, and is not for another.
But Protagoras did not even attempt to provide a scientific justification for his position. This
is clear from the fact that neither Plato nor Aristotle—to whom the text was surely available—
could trace the means by which he arrived at it. Both were guided wholly by conjectures,
a procedure in which Aristotle, completely acquainted with the historical antecedents,
and certainly more abundantly equipped with a historical sense, was the more successful.
I have pointed out the steps on the path towards the Protagorean thesis. Parmenides
also says: “What can be thought is only the thought that it is.”* What could be more
obvious than the paradox that every thought is true? Every belief, obviously, is in complete
agreement with itself, and therefore, given the presupposition in question, every belief is in
complete agreement with its object.
14. But let us not remain any longer with the historical antecedents of the Aristotelian
definition of truth. Let us see the effect it has had upon later thinkers. What we find is that,
with insignificantly few exceptions, it is standard up to our own time.
15. Medieval thought agrees in saying that true and false in the strict sense is to be found
in judgement, and defines truth as “adaequatio rei et intellectus”.
* Trans. Kirk and Raven, The Presocratic Philosophers.