Processing math: 100%

Proof

(related to Lemma: Denying the Antecedent of an Implication)

We want to prove that the mixing-up the sufficient and necessary conditions is a fallacy. * The fallacy can be formulated in propositional logic as (p\Rightarrow q)\wedge \neg p\Rightarrow \neg q. * The definitions of the implication "$\Rightarrow$" and the negation "\neg" give us the following truth table of the function:

[[p]]_I [[q]]_I [[p\Rightarrow q]]_I [[\neg p]]_I [[\neg q]]_I
0 0 1 1 1
0 1 1 1 0
1 0 0 0 1
1 1 1 0 0

Thank you to the contributors under CC BY-SA 4.0!

Github:
bookofproofs


References

Bibliography

  1. Kane, Jonathan: "Writing Proofs in Analysis", Springer, 2016