I’ve written this up a few times and it only seems to get more and more confusing so I’m ditching formality. I can’t seem to wrap my head around Plato’s idea of morality or perception (which are so heavily reliant on each other). Okay, so to start off, we need to consider Thrasymachus, the only person to persistently argue against Socrates in that morality is relative. Book II is dedicated to prove Thrasymachus wrong but Socrates only really disproves Thrasymachus’ literal statement that “justice is nothing other than what is advantageous for the stronger” (338c) by arguing that a just man lives well and therefore advantageously but whether or not a just man lives advantageously is not what determines whether or not justice has one absolute definition. Yet, the book goes on and we nearly never hear of the possibility of individually relative perception/definition of justice/morality but we do hear a whole lot of agreeing to Socrates’ opinions on how we all ought to live.
Later on, in Book 7 we’re introduced to the allegory of The Cave. To explain the entire education and perception of man, Plato puts all of mankind in a cave where they are only able to look at one wall where shadows of imitations of what is outside the cave are projected. This means that everyone is receiving the same information but no one is able to see anyone else’s perception or what is actually even there. Then, Plato takes philosophers out of The Cave where they see how the world really is and then they are forced back in to live the rest of their lives in the grave dimness that is the world of the “cave-people”. But how do we know that those who left saw the same thing if neither of them could ever explain it? How do we know that the Forms have absolute structures if their structures could very well be completely different to those who have seen them but equally indescribable? Can we really trust Plato as the only person who knows what is true if he needs to lie (a lot of lies that are to his political and social gain) to get the rest of us barely close enough to see the “real truth”?
P.S – This was supposed to be posted last week but I have had a lot of computer trouble. Sorry.
Really good questions here! We do hear later in the book just a little, but a very little, about the idea of justice being relative. In Book V, when they’re talking about people who have knowledge vs those who have opinion or ignorance, they discuss how the many beautiful things, as opposed to the “beautiful itself” (the form) can appear ugly, and the many just things can appear unjust, etc. (479a-c or so). The form of beauty, justice, etc., is always the same but things that are beautiful can appear so to some but not others, can be beautiful at some times but not later, etc. That’s at least hinting at the the idea of relativism in morality.
However, you’re right that we don’t get a rock solid answer as to why we should believe that those who understand the forms are understanding the same thing. I think what he’s trying to say at the end of Book V is that if someone has understanding of a thing that is always just, never changes, never appears different to different people, then that would be the true form and they would have knowledge. If you don’t have that sort of understanding, then you don’t get the form and don’t have knowledge. But the problem is, how does one know when one has that? And even worse: how does one know that others who claim to have it, actually do?
All we get from Plato, I think, is a gesture towards the method of “dialectic” (Book VII, 531e-533d), which seems to be an activity of reason whereby one uses argument to determine the nature of the forms, but without any reference to visible images like drawings of circles or triangles, and without making assumptions that aren’t themselves questioned. What, exactly, this looks like is unclear, but it’s at least possible that those who claim to know the forms could compare their arguments with each other, discuss together, and perhaps thereby see if they agree? But honestly, this is a guess. I’m really not sure if, in Republic, there is a good answer to how those who claim to know the forms can be shown to actually do so.
On a different note, can you activate the plugin that allows those who make comments to check a box to get an email if there are any replies? When you’re logged in to the dashboard of this site, go to “plugins” on the left menu, then find “subscribe to comments” in the list of plugins and click “activate” to the right of that. Thanks!