Invalid arguments with true premises and true conclusion
47926
What is the logical form of the definition of validity?
126713
Strong induction and vacuous truth
130028
Why is a statement "vacuously true" if the hypothesis is false, or not satisfied?
152827
Defeating Russell's paradox
56325
If we accept a false statement, can we prove anything?
12186
How does predicate logic handle contradictory statements about something that does not exist?
61303
"Infer" vs. "imply" — can "infer" imply "imply"?
20658
Difficulty in finding a counterexample
578
In classical logic, why is $(p\Rightarrow q)$ True if both $p$ and $q$ are False?
144396
fitch style proof problem regarding rule of inferences
36838
Using the compulsory argument for the optional argument?
32244
Propositional Logic - Deduction
68265
Why is it sensical for a proposition with a false antecedent to validate to true?
23752
Proving Irrationality
110494
Creating truth tables
109685
An invalid argument, the conclusion of which is a tautology
105303
'Obvious' theorems that are actually false