Talk:Lewis's triviality result

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Philosophy: Logic / Analytic Low‑importance

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A → B edit

Latest comment: 1 year ago4 comments3 people in discussion

Figure 1 purports to show [A → B] as one of the sets in the Venn diagram. But if [A → B] means the same thing as what it is usually taken to mean in propositional logic, then [A → B] is the same thing as [B ∪ A′ ]. Thus its probability should be 1 − x − y, or equivalently, s + t + u + v + w + z. How can the set labeled [A → B] in Figure 1 be regared as [A → B]? Michael Hardy (talk) 22:08, 27 September 2018 (UTC) @Knorlin:Reply

ok, So it appears that the expression “[A → B]” is not intended to mean what it usually means in propositional logic. I think the article should be explicit about that. Michael Hardy (talk) 22:25, 27 September 2018 (UTC)Reply

I added a clarifying note to the figure caption. Thanks for the observation. Knorlin (talk • contribs) 17:41, 8 March 2021 (UTC)Reply

"[A → B] is the same thing as [B ∪ A′ ]."

This is wrong. See the truth table here https://en.wikipedia.org/wiki/Material_conditional

When A is false, and B is true, A -> B is true. CrickedBack (talk) 07:45, 26 December 2022 (UTC)Reply

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