Credo in Unum Deum

I Believe in One God

Protagorian Relativism: Plato and Aristotle Respond

“Man is the measure of all things, of the things that are, that they are, and of the things that are not, that they are not.”(1) Plato’s actual words in the mouth of Socrates are, “[Y]ou know that he [Protagoras] puts it something like this, that as each thing appears to me, so it is for me, and as it appears to you, is for you—you and I each being a man?”(2)

Plato and Aristotle attacked vigorously this statement because it seemed to make objective knowledge impossible; that is, we cannot know truly the way things are and therefore cannot philosophize about the nature of things. What we are left with is a world which seems to me to be a certain way, but may seem to you to be a different way. But that’s okay.

Plato and Aristotle went about dismantling this idea by asking whether this doctrine applied to itself. That is, if a is true for me and a is false for you, then it seems that a is both true and false at once! Applied to Protagoras’ maxim, the maxim refutes itself since if it is true it is false.

In his book, The Presocratic Philosophers, Jonathan Barnes contends that this objection by Plato and Aristotle does not really work in that it misapprehends what Protagoras was actually trying to say. For example, Barnes contends that Protagoras is not guilty of advancing a self-refuting premiss since the argument suggests that when I judge something to be the case as it appears to me, I am judging correctly. Of course, I cannot misjudge the contents of my judgments. Therefore, if I judge that the wind is cold for me I am judging correctly. Also, since Protagoras believes that, “[f]or any proposition P there is an argument for P and an argument of equal strength for not-P”(3), even a supposed mathematical certainty could be questioned and its negation shown to be as likely as its assertion, as when he, according to Aristotle, “refuted the geometers.”(4)

But this is all sophistry. Shall we commit it to the flames? If knowledge is private and not public, then it seems to me that Protagoras’ epistemology doesn’t really even get off the ground. Sure, we may not be contradicting one another strictly when we report our subjective judgmental “seemings” (I judge that A seems to be, or is, R for me), but then what really does Protagoras have to say to me? I have no reason to listen to him or adopt his epistemology especially since there are just as good reasons to reject his epistemology, according to his own argument. So it appears that while Plato and Aristotle might (maybe, just maybe, but I doubt it) have misapprehended Protagoras’ position, the strength in their refutation lies in its public, objective status. Of course, if truth is unknowable in an absolute sense, then we are all on equal footing. But if it is knowable, then Protagoras needs to rework his epistemology.

1 McInerny, Ralph. “A History of Western Philosophy.” 1963: University of Notre Dame Press. <;

2 Levett, M. J., rev. Burnyeat, Myles. “Theaetetus.” Plato: Complete Works. Ed. John M. Cooper. Hackett Pub. Co., Inc.: Indiana, 1997. 169

3 Barnes, Jonathan. The Presocratic Philosophers. London and New York: Routledge, 1982. 545

4 Ibid. 546


September 4, 2007 - Posted by | Philosophy

No comments yet.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: