The dialogue is interesting, however, in that it shows us a slice of the complicated interaction and occasional dispute between philosophers, following people like Socrates and Plato, and rhetoricians, following people like the orator Isocrates, that begins with Plato and, developing through the Hellenistic period, extends even into the Roman Imperial period. It has, in fact, been suggested that the Sisyphus is devoted to criticizing the work of Isocrates, who made deliberation a major element in his rhetorical theory, as the Meno is sometimes taken to be doing. At a much later date, we find another iteration of the Sisyphus dispute in the works of the orator Dio Chrysostom. Dio Chrysostom's twenty-sixth discourse, subtitled 'On Deliberation', rehearses arguments very similar to those given in the dialogue. Indeed, the arguments are in places so similar that the only two serious explanations of the similarity are that the Sisyphus author and Dio Chrysostom are both following a third source very closely or (much more probably) that Dio Chrysostom is adapting the Sisyphus argument to his own purposes.
The dialogue is also interesting in that it probably does give us some idea of how thinkers in Plato's Academy discussed this topic, drawing on Plato, but not being afraid to go beyond him.
(in order of appearance)
Sisyphus of Pharsalus
There are occasional scattered references to a Sisyphus who led Pharsalus, in Thessaly, and it is probably the same person. It is notable that the Meno of Plato's dialogue is also from Thessaly (although a different city), strongly suggesting that any connections to the Meno are deliberate.
Socrates opens by addressing Sisyphus, saying that Socrates and his companions had waited a long time yesterday for him; apparently they were all to attend a show by Stratonicus of Athens. Sisyphus, however, never showed. Sisyphus excuses himself by saying that he was called to join the deliberations of the authorities in Pharsalus and therefore could not get away. To this Socrates replies that obeying the law is an excellent thing and that it is also good to be considered a good deliberator by one's fellow citizens. He proposes, however, a discussion of what deliberation could possibly be. Sisyphus is a little baffled at the suggestion that Socrates does not know what deliberation is, but Socrates insists that he doesn't. They then discuss the relationship between deliberation and knowledge. The dialogue ends with Socrates suggesting that the issue would be worth further discussion at some other time.
* Stratonicus of Athens was a musician. He seems to have had a reputation for witty sarcasm and satire, since several proverbs and clever comebacks are attributed to him, but relatively little seems to be known about him.
The essential puzzle of the dialogue is how deliberation differs from guessing or divination. What makes it different from just playing a game of odds-and-evens (i.e., the game, still played today, of guessing whether someone is holding up an odd or even number of fingers). Sisyphus points out that deliberation does not involve complete ignorance but instead partial understanding in which one tries to find things out. But Socrates replies that deliberation, as a way of finding things out, could not be about what people know but about what they don't know. He gives examples from geometry, like finding a diagonal or doubling the cube: you don't deliberate about whether it is diagonal or about whether it is a cube, but you look for something you don't know. The same is true of cosmological speculations. So Socrates concludes:
In all such cases, then, our conclusion is as follows: nobody can ever try to find out anything that he knows, only what he doesn't know. (389a)
He then suggests that deliberation consists in "somebody trying to find out the best course to follow in matters requiring him to take action" (389b) and that, apparently, what prevents people from finding it out is lack of understanding. He argues this last point with several examples: no one can genuinely deliberate about music, or military strategy, or anything else, unless they understand what they are deliberating about.
From this it follows that deliberation and trying to find things out cannot be the same: we only try to find things out if we don't understand them, and we only genuinely deliberate when we do understand them. Thus it doesn't seem that the Pharsalians were actually deliberating; they were just trying to discover things they didn't know. Socrates then asks Sisyphus whether it makes more sense, if you don't know something, to learn it from someone who does or to try to discover it all on one's own. When Sisyphus says it makes more sense to learn it from someone, Socrates criticizes the Pharsalians on that ground for stumbling around on their own rather than taking the trouble to find someone from whom they could learn what they needed to know.
The dialogue then shifts with Socrates asking about good deliberation. He gets Sisyphus to agree that there is a definite distinction between good and bad deliberation, and then that those who deliberate do so about future things. The future, however, does not exist yet, and thus has not come into being. But if the future has not even come into being, it has no definite nature. But suppose we imagined some archers and were testing whether they were good archers or bad archers. We'd usually do this by setting up a target and having them shoot at the target. But what if there were no definite target, and we just told them to shoot? How could we distinguish good and bad archers? And what corresponds to aiming at a target in deliberation is understanding what one is deliberating about. Since the future has no definite nature, it cannot be understood, so if deliberation is about future things, no one can be good or bad at it.
So we end the dialogue with an unanswered question: what is the real standard for good or bad deliberation? In addition, if the argument of the dialogue is right, we can only deliberate about what we know and we cannot deliberate about the future. Since we usually treat deliberation as being precisely about these things, we do seem to have quite the puzzle on our hands! Which, as we see from Socrates' parting insistence that it's worth thinking through sometime, is precisely the point.
All quotations from David Gallop's translation in Plato, Complete Works, Cooper & Hutchinson, eds., 1708-1713.