In English it doesn't really make much sense to talk about having an opinion about where a place is.
In my opinion Canada is east of Texas. What?
I may believe Canada is east of Texas, but surely there is some basis for this belief... maybe somebody told me that. If I say I believe it, but don't know it, that reflects a lack of confidence in my source.
If we're trying to see a distinction between knowledge and belief by suggesting that one is based on authority and one is not, we're going to flounder.
To base knowledge on authority is equating knowledge to belief: belief in the authority.
If by "basis" you mean justification, some people believe things without any justification at all. If by "basis" you mean cause, then, of course, all my beliefs are caused in some way or other. But the cause need not be a justification. My belief in God may be caused by my upbringing. But that doesn't justify my belief in God.
The Greek is "doxa" which can be translated either as "opinion" or as "belief". Sometimes my justification for what I know is authority. For instance, I know that the word, "weird" is spelled that way because I looked it up in the dictionary, and the dictionary is the authority on how words are spelled. It is my justification for believing (and also knowing) that "weird" is spelled that way. Belief and knowledge are different, but that does not mean that they exclude one another (although Plato did think they did). In fact, I cannot know that Quito is the capital of Ecuador unless I also know it is. Knowing implies believing; although believing, of course, does not imply knowing.
---------- Post added 11-17-2009 at 08:33 AM ----------
this would be part of the attempt to differentiate doxa from episteme, might it not? Where doxa is an opinion, and episteme, true knowledge. It seems to me to be much easier to judge the equivalence of the two in a case where the outcome can be settled easily, such as the directions to a town, than in regards to abstruse questions regarding the nature of life.
Anyway - I would like to hear what further Socrates had to add....
There are two important differences between believing and knowing:
1. You can believe what is false, but you cannot know what is false. Believing does not imply truth, but knowing does imply truth.
2. You can believe without any justification, or very little justification. But you cannot know without adequate justification.
What Socrates says is no mystery (although what he means, or whether it is true, may be)
I admit the cogency of your argument, and therefore, Socrates, I wonder that knowledge should be preferred to right opinion-or why they should ever differ.
And shall I explain this wonder to you?
Do tell me.
You would not wonder if you had ever observed the images of Daedalus; but perhaps you have not got them in your country?
What have they to do with the question?
Because they require to be fastened in order to keep them, and if they are not fastened they will play truant and run away.
Well. what of that?
I mean to say that they are not very valuable possessions if they are at liberty, for they will walk off like runaway slaves; but when fastened, they are of great value, for they are really beautiful works of art. Now this is an illustration of the nature of true opinions: while they abide with us they are beautiful and fruitful, but they run away out of the human soul, and do not remain long, and therefore they are not of much value until they are fastened by the tie of the cause; and this fastening of them, friend Meno, is recollection, as you and I have agreed to call it. But when they are bound, in the first place, they have the nature of knowledge; and, in the second place, they are abiding. And this is why knowledge is more honourable and excellent than true opinion, because fastened by a chain.
What you are saying, Socrates, seems to be very like the truth.
I too speak rather in ignorance; I only conjecture. And yet that knowledge differs from true opinion is no matter of conjecture with me. There are not many things which I profess to know, but this is most certainly one of them.
Yes, Socrates; and you are quite right in saying so.
And am I not also right in saying that true opinion leading the way perfects action quite as well as knowledge?
There again, Socrates, I think you are right.
Then right opinion is not a whit inferior to knowledge, or less useful in action; nor is the man who has right opinion inferior to him who has knowledge?
And surely the good man has been acknowledged by us to be useful?