Of course, there are other more speculative possible ways ofexplaining why Plato so often makes Socrates his principal speaker. Forexample, we could say that Plato was trying to undermine the reputationof the historical Socrates by writing a series of works in which afigure called “Socrates” manages to persuade a group ofnaïve and sycophantic interlocutors to accept absurd conclusionson the basis of sophistries. But anyone who has read some of Plato'sworks will quickly recognize the utter implausibility of thatalternative way of reading them. Plato could have written into hisworks clear signals to the reader that the arguments of Socrates do notwork, and that his interlocutors are foolish to accept them. But thereare many signs in such works as Meno, Phaedo,Republic, and Phaedrus that point in the oppositedirection. (And the great admiration Plato feels for Socrates is alsoevident from his Apology.) The reader is given everyencouragement to believe that the reason why Socrates is successful inpersuading his interlocutors (on those occasions when he does succeed)is that his arguments are powerful ones. The reader, in other words, isbeing encouraged by the author to accept those arguments, if not asdefinitive then at least as highly arresting and deserving of carefuland full positive consideration. When we interpret the dialogues inthis way, we cannot escape the fact that we are entering into the mindof Plato, and attributing to him, their author, a positive evaluationof the arguments that his speakers present to each other.
Socrates (Stanford Encyclopedia of Philosophy)
That is to say, Times Square can be photographed; but someone only seeing the photograph will only know what the Square is in the vaguest of senses. The reality of being there is lost by the photograph, and no picture or even video can truly capture what that experience is like. However, to someone that has been to Times Square, a picture will help them reminisce about it and in some ways evoke that knowledge of the place. Socrates saw writing in the same way: writing cannot be used as a sort of standalone memory bank because people who read a text will only have a partial understanding of the author’s meaning, and therefore should not be taken seriously. However, writing can be used as as entertainment, for example to help someone reminisce about something they wrote down. In other words, if you’re not already familiar with the real knowledge that’s written down, you can no more learn it from a text than you can know what it feels like to be in Times Square from a photograph.
Plato, from The Phaedrus - Miami University
In the , written circa 370 BCE, recorded Socrates's discussion of the Egyptian myth of the creation of writing. In the process Socrates faulted writing for weakening the necessity and power of memory, and for allowing the pretense of understanding, rather than true understanding.
Dialogues of Plato - Internet Sacred Text Archive