Sorry my bad. I was assuming that since you used it, he did too. I have been consulting my other translations and ignoring the Jowett.
But what is to the point is that anyone (including Plato) who proposes the idea is obligated to argue for it. He may not be talking about knowing ordinary truths, but then, so what? If by "higher knowledge" he only means knowledge of "higher truths" and not just ordinary truth like that Quito is the capital of Ecuador, then he ought to say that. But that has nothing to do with different kinds of knowledge. It has to do with knowledge of different kinds of truths. And, that distinction is obviously important.
So you think there are different kinds of truths? If so, what are some examples?
It still does not follow that because a belief is true that is cannot be false, as Socrates claims. Contingent truths are true, but they can be false.
If someone says "contingent truths cannot be false", what precisely do they mean? Is it a metaphysical claim, i.e. that there is only one logically possible universe? But then the truths wouldn't be contingent, would they? The idea that contingent truths cannot be false sounds like a contradiction (= contingent truths are necessary).
In any case, I don't think it makes any difference to the issue at hand whether it is "true belief" or "right opinion". It still does not follow that because a belief is true that is cannot be false, as Socrates claims. Contingent truths are true, but they can be false. (And it doesn't matter whether we substitute "right opinion" for "true belief". The point is the same). The problem is what matters, not the translation.
a.k.a, 'higher truths'
I can't put my hands on a quote from the Dialogs, but I think about it this way (perhaps more Buddhist than Platonic but I am sure there are parallels). One of the hallmarks of sagacity or the philosophic temperament is disinterestedness - absence of self-interest. Ordinary people are driven by passions, likes and dislikes. So their every act and perception is coloured by 'what I want' or 'what I believe'. In the absence of the passions, the sage is much more able to discern what is truly the case by not acting from self-interest. Consider the last speech of Socrates - I think this was a good example. He was looking at the whole situation from the viewpoint of the State, not from his own viewpoint, and was able to be completely unaffected by his own imminent demise.
This sense of detachment from self is, I am sure, a prerequisite for what the traditional cultures understood as the higher knowledge. This is very much at odds with our own culture which puts so much emphasis on the self and individual perogative.
I think the source for this understanding is The Parmenides. There is a great deal in it, about how that which is real cannot pass away, and that which is always changing cannot be said to truly exist, and therefore can't be said to be an object of true knowledge. But I don't have it on hand, perhaps someone with a copy might be able to find some supporting quotes. (I do recall that when I studied it at University, I found it very difficult to fathom.)
There is a great deal in it, about how that which is real cannot pass away, and that which is always changing cannot be said to truly exist, and therefore can't be said to be an object of true knowledge.
What's that quote? That Western Philosophy is footnotes to Plato? Sure, we should include Plato's influences, but I think he was right. (Whitehead?)
We basically have Plato and the inversion of Plato. That's pretty much the spectrum. But even the inverters of Plato are still speaking the Truth, or else they are not exactly philosophers. I love Nietzsche, but this contradiction still seems to apply to him and all the moderns he influenced. I love Rorty also, and he too is in this camp. I'll salute Rorty for knowing it, for having a Cheshire grin. Doesn't Western Science seem to stem directly from Platonic notions? The form beneath the flux.
Doesn't Western Science seem to stem directly from Platonic notions? The form beneath the flux.