What mathematical models can we use to represent the truth value of an opinion? Obviously, I don't think we can use boolean, except in cases where the opinion of a person represent a statement of fact, but what about other situations, what are some solutions proposed by philosophers and mathematicians?

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    Would Baysesian networks be appropriate? en.wikipedia.org/wiki/Bayesian_network
    – BillOnne
    Aug 28, 2022 at 1:30
  • Not so fast, this could be ill-formed. You are assuming that opinions have truth values, which is not necessary correct (e.g. millions' opinions are God exists, but that doesn't give such belief any value of truth for an atheist). You can just give them weights (e.g. my decision is impacted by the opinion of my friends in some F factor). I would not associate opinions with beliefs or degrees of truth, or bayesian probabilities as in previous comments (in politics, the outcome is not related to probability, but to subjective positions). Weighing goes fine with subjective/objective opinions.
    – RodolfoAP
    Aug 28, 2022 at 6:52
  • @RodolfoAP I do not think he is assuming that, he is only assuming that some philosophers and mathematicians proposed that in some situations, which is, indeed, the case.
    – Conifold
    Aug 28, 2022 at 8:19
  • @RodolfoAP, saying that an opinion has a truth value doesn't mean that it is true; it means that it is either true or false. it's like saying that a mathematical equation has a numeric value. Aug 28, 2022 at 9:47

1 Answer 1


I don't think we can use boolean, except in cases where the opinion of a person represent a statement of fact,

Everything we say is opinion, and opinion based on some fact.

Perhaps the real issue would be what or which facts.

Thus, there are no different sorts of truth values. Meaningful statements are supposed to be true or false, and nothing else. Opinions are just as true or as false as any true statement of fact will ever be.

We can of course qualify any statement of fact as our own opinion, but this goes without saying. Someone who supports their claim by saying that the claim is supported by some academic authority is only really voicing their opinion that this academic authority has more value than something else. Ultimately, everything that we assert is grounded in our own personal opinion. Our belief that most people have the same opinion as we do is itself just an opinion.

There is no good reason to try to distinguish between the possible truth values of a "statement of fact" versus that of an opinion. We can always qualify a claim we or other people make, but this cannot possibly affect the truth value of the claim. A claim is true or false, irrespective of who makes that claim, irrespective of the respectability of the author of the claim, and irrespective of what people think.

There is only one case where we can tell, and this is when the claim is false because it is self-contradictory, and then even that is not so simple.

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