I've been mulling over the question "can an opinion be wrong?". It's an interesting question to answer.
It seems dependent on what kind of opinion we're talking about. If the opinion is pure opinion, like an aesthetic or other personal preference, it seems pretty ironclad, but opinion rooted in belief can definitely be debunked if the beliefs are demonstrably untrue.
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But what about a pure opinion, like the answer to the classic question "Do you prefer chocolate or vanilla". There are only 4 real answers to this question (Chocolate or Vanilla, or less frequently Both or Neither), and none of them are based in disprovable belief.
Or are they? What if you followed up with the question "Why?" - would the answers still meet the definition of pure opinion?
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But what if someone answers "Vanilla! They don't want you to know this, but chocolate is made from geriatric dog feces from farms upstate where they send old dogs. Cocoa beans aren't even real, wake up sheeple! Chocolate is just dog shit!"?
Immediately you understand that the opinion of vanilla over chocolate in this context is based on an easily debunked conspiracy theory. That's enough for me to at least determine that this opinion is invalid, as it is rooted in a clear falsehood.
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@Alex
If you ever think about something carefully before offering an opinion you never qualify it with "just my opinion". "Just mu opinion" is just an excuse to mouth off without thinking.
Following up with "Why?", and get might neutral answers like "I prefer vanilla because I find chocolate bitter", or "I prefer chocolate because it is richer than vanilla", or even "I don't know, I just like x better than y". None of these are invalid or wrong. They're still solidly in the realm of pure opinion.
There's no belief here to be challenged, only subjective statements of preference that extrapolate on the original question.
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