In a proof by contradiction, what if both the proposition and its negation lead to contradictions?
43700
Are proofs by contradiction really logical?
15504
In classical logic, why is $(p\Rightarrow q)$ True if $p$ is False and $q$ is True?
93327
Negation of if and only if?
37134
How can I solve this logic question using propositional logic (Natural deduction)?
113344
How do we prove that something is unprovable?
109858
How could a statement be true without proof?
40048
Finding the fallacy in this broken proof
142762
how to prove that (P⊃Q)≡(¬Q⊃¬P) ( P ⊃ Q ) ≡ ( ¬ Q ⊃ ¬ P ) is disallowed in intuitionistic logic?
35433
When does a dual of a compound proposition equal itself?
113605
In Fitch, how does one prove "(P → Q)" from the premise "(¬P ∨ Q)"?
143627
Use the Fitch system to prove the tautology (p ∨ ¬p)
93557
Intuitively, why does (B → S) ≡ (¬B ∨ S)?
56325
If we accept a false statement, can we prove anything?
140634
Double negation and litotes
12186
How does predicate logic handle contradictory statements about something that does not exist?
126633
Is a contradiction enough to prove a set equality to $\varnothing$?
30733
Negation as failure in Prolog is a procedural behavior?