There are two types of opinion.

1. One which must be reasoned to, like knowledge. This happens when, in a group, certain individuals are asked for their input on an issue.

2. The other kind of opinion is about taste and preference and this needn't be argued positions.

I guess in logic, ''opinion'' refers to the second kind. It's a technical word in that respect and contrasted with knowledge which requires justification.

The answer to this will depend on what you think you can know, and of course how.

There are those opinions where the answer is obvious. Having blue as your favorite color or liking one sports team over another is a purely subjective preference and unrelated to knowledge. But you are probably wondering about opinions as beliefs about the world, I.e. something you are of the opinion that X is true or will happen.

For the realm of empirical knowledge, it would depend on what theory of science you ascribe to. A Bayesian would probably argue that since all statements about empirical reality can be expressed by probability, having an opinion or belief is only quantitatively different from having knowledge. I don't know enough about the current state of the discussion to say whether there are theories that allow two competing theories to have equal standing pending further evidence. In that case there would be room for a genuine opinion.

In other fields, it depends on whether or not knowledge is possible, and what it means. In general terms I would say that as long as there is a single, true answer to a question, there can be no opinion on the matter that is qualitatively different from knowledge. Calling it an opinion is then purely a statement about your access to the relevant information, not a statement about the claim itself.

These, along with belief, are just judgements with degrees of certainty. An opinion has no sufficient certainty at all, as in “I think this party will win the elections”, insofar as no conditions are given to justify the “I think” part of the proposition.

A belief has subjective sufficiency, but no objective sufficiency, insofar as, again, “I believe this party will win the elections because this party has always carried enough voting districts” adds conditions sufficient to qualify the “I believe” part of the proposition but the predicate “because this party has always carried enough districts” is insufficient to justify the objective certainty of “will win”.

Knowledge is a different sort of creature, it’s certainty, at least with respect to the world, can only be derived from experience, in which case the original propositions cannot apply, but “This party has always won because they always carried enough districts” is a judgement with objectively sufficienct conditions (ballot count, show of hands, yeas and nays) warranting the certainty of the knowledge “has won”.

Then of course, there’s always inductive/deductive reasoning, necessary/contingent conditions, top down/bottom up.......but ehhhhh....too technical, methinks.

Now the two are hard to define but it think in general opinion is when you look at the data and draw a concussion (Even if the data is very little). Knowledge is something derived from facts using the method defined in the postulates.

Whilst I am in no means attempting to fully answer your question, as I do not hold within me the aptitude to do so properly, I would propose that the supposition of knowledge not needing justification is impractical to its own meaning.

Justification is a requisite of knowledge, as knowledge is something that can be had.

Truth or whatever other term may be equivocated with the term that is 'knowledge' exists regardless of its relation to an observer/learner.

(P.S) Someone please let me know how I've done on my first post! I'm new to this forum and I definitely want to avoid making mistakes and spreading any semblance of falsehoods. Thanks!

A held opinion is a belief, X knows that P iff X has a justified true belief that P is a reasonable approximation to knowledge that. There are ambiguities; see fallibilism and and epistemic luck. Also see hinge propositions for another complexity. Accounts here look like accounts of truths, justifications, beliefs and relationships between them.

Sociologically/anthropologically, what matters is what is usually treated or presumed as true. Another wrinkle here is that knowledge might not be just a relationship between an agent and a proposition, it might be a relationship between an agent and an interdependent system of other agents, texts and interpretive norms; knowledge institutionally is a collaborative endeavour whose production requires trust of sources and a commitment to the truth from all involved. Accounts here look like (historical) descriptions of scientific and institutional practices.

Also, knowledge-that is under half of knowledge, knowledge-how or competence/skill plays a big role and requires a much different approach to analyse. Knowledge-that may require knowledge-how to get going.

My take, an opinion is an unsupported belief. It certainly can be true and useful, but it either can't or is not for some reason defended. Knowledge can be defended by reason. Knowledge is then a true opinion accompanied by a rational defense, or a justified true belief.

being true’ with regard to knowing is being in accord. Beiing ‘ true’ to the facts as being in accord or correctness is a matching between an actual state of affairs and one’s claim or opinion about that state of affairs.
Proof or validation is a successful corresponding between opnion amd the situation.
But situations are never simply facts in themselves but are interpreted. So knowledge attempts to match opinion with a situation that is already interpreted by the opinion. Thus knowledge and opinion are entangled from the start.

Some more thoughts
Knowledge is something that has evidence = memory, testimony, experience, logical
there can be many reasons for justifying an opinion but it can never be proved.
May be that could be one difference between knowledge and opinion
Also is Belief same as opinion. Looks like they are same. But not sure.