Nassim Taleb has written a book (here) promoting things that are the opposite of fragile, and in it he talks quite a bit about my own area of expertise, Greek philosophy. (No, I don’t understand why he focuses on the Greeks rather than, say, Descartes, or even why he talks about philosophers so much at all.) Taleb talks about someone he knows named Fat Tony, whom he believes would give Socrates a run for his money if the two were ever to meet. He imagines that Fat Tony would end up questioning Socrates instead of the other way around and that he would demand that Socrates explain why we need to define things, given that there are plenty of things we know about even if we can’t define them.
This completely misunderstands what Socrates was up to, which I learned about in a seminar with this scholar. Socrates would question people about their knowledge only if they claimed to have knowledge. Moreover, he was especially interested in moral knowledge. Consider the Euthyphro, for example, which Taleb himself comments on. The discussion gets going because Euthyphro claims to have knowledge of piety and impiety: “But [my relatives’] ideas of the divine attitude to piety and impiety are wrong, Socrates” [4e]. When Socrates asks a question to clarify this, Euthyphro adds, “I should be of no use, Socrates, and Euthyphro would not be superior to the majority of people, if I did not have accurate knowledge of all such things.”
It is at this point that Socrates begins his questioning of Euthyphro. It is at this point that he starts demanding a definition of piety. It's because Euthyphro not only claims to have knowledge of piety, but also claims that his knowledge is superior to that which others have.
Taleb describes this scene quite inaccurately, saying the following:
Socrates’ technique was to make his interlocutor, who started with a thesis, agree to a series of statements, then proceed to show him how the statements he agreed to are inconsistent with the original thesis, thus establishing that he has no clue as to what he was talking about. 
No, the interlocutor does not start with a thesis, but rather with a claim to knowledge. And that is why Taleb is wrong to say this: “Now assume that Fat Tony was asked by Socrates how he defined piety.” Socrates just would not have asked Fat Tony for a definition of piety. Based on Taleb’s description, Fat Tony would never have claimed any knowledge of piety, and so Socrates would have ignored him. If they had met, they would have engaged in unimportant chitchat
Would Socrates have engaged with Fat Tony about finance, which is Fat Tony’s area of expertise? Nothing Plato writes about Socrates suggests he was interested in that kind of knowledge. The closest one can come to this is when Socrates says he talked to craftsmen, and he admitted that they had knowledge of their craft, but then he adds that they also thought they had knowledge of other things, which they did not have [Apology 22c-d]. However, Taleb portrays Fat Tony as being uninterested in the distinction between True and False and prefers sucker and nonsucker instead . In other words, Socrates would never have had a philosophical discussion with the fellow.
Let me suggest that Plato’s big goal in life was to find moral experts, people who can give definitive and final answers to all moral questions. In his early period (which includes the dialogue Euthyphro) he looked for and failed to find anyone with such expertise. In his middle period, he thought he had found a way to produce such experts: they are the people who had knowledge of the forms. In his late period, he was fending off criticisms of the forms from his nephew Speusippus.
If we think of a world with true moral experts as a sort of paradise, we can then characterize these three periods as (1) paradise sought, (2) paradise gained, and (3) paradise lost. There. All of Plato for you in just a few words.