Talk:Lewis's triviality result

A → B
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 &cup; A&prime; ]. Thus its probability should be 1 &minus; x &minus; 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)


 * 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)


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