I am at work on a precis of my entire argument and hope to a have a rough draft of it in a few weeks. (This is why my posts have been few and far between of late.) Currently I am at work on the section dealing with the nature of doxa, i.e. opinion. To state my nutshell opinion on opinion: while it certainly differs from knowledge, as the quotes listed below make clear, it is not a matter of knowledge instead of opinion as much as knowledge through opinion. Opinion is the proper medium of knowledge and the trick that Plato would have us learn is to employ it as a means and not the end of thought. Opinion is not enough to satisfy a healthy intellectual eros — it is defective — and the thought that encompasses both opinion as satisfying belief and dissatisfying doubt is a lens toward the noetic light that illumines knowledge.
Anyway, here are some quotes from Plato’s Meno that bear partially on my thesis. (The translation I am citing is that by Anastaplo and Berns, published by Focus Philosophical Library, 2004.) Feel free to comment on any of these.
1. True opinion, therefore is no worse a guide to right action than prudence. (Meno 97b)
2. He who has knowledge would always hit the mark, whereas he who has right opinion would sometimes hit it sometimes not. (Meno 97c)
3. True opinions, for as long a time as they should stay put, are a fine thing and accomplish all kinds of good things. Yet much of the time they are not willing to stay put, but run away out of the human soul; so that they are not worth much until someone should bind them with causes by reasoning. And this, my comrade Meno, is recollection, as we agreed before. And whenever they have become bound, first they become knowledge and then steadfast. And this is why knowledge is worth more than right opinion, and by its binding, knowledge differs from and excels right opinion. (Meno 97e-98a)
4. I too speak, not as one who knows, but as one who makes images and conjectures. But I certainly do not think I am making images or guessing this, that right opinion and knowledge are different things. But if there is anything I could affirm that I know, and there are few that I could affirm — one of those at any rate which I set down that I know is this. (Meno 98a-b)
5. If…true opinions will exist within him [i.e. the slave boy], after which being aroused by questioning become matters of knowledge, then will not his soul for all time be in a condition of having learned? (Meno 86a)
6. And in what way will you seek, Socrates, for that which you know nothing at all about what is? What sort of things which you do not know are you proposing to seek for yourself? Or, even if, at best, you should happen upon it, how will you know it is that which you do not know? (Meno 80d)
7. I would not assert myself altogether confidently on behalf of my argument; but that in supposing one ought to seek what one does not know we would be better, more able to be brave and less lazy than if we supposed that which we do not know we are neither capable of discovering nor ought to seek — on behalf of that I would surely battle, so far as I am able, both in word and in deed. (Meno 86b-c)
8. Inasmuch as all nature is akin and the soul has learned all things, there is nothing to prevent someone who recollects (which people call learning) one thing only from discovering all other things, so long as he is brave and does not grow tired of seeking. For seeking and learning therefore consist wholly in recollection. So that one should not be persuaded by this contentious argument. For it would make us lazy and is pleasant only for fainthearted people to hear, but the other argument makes us both ready to work and to seek. Trusting in this one to be true, I am willing with you to seek for whatever virtue is. (Meno 81d-e)