4 ms·
It does, insofar as you can express anything meaningful in an inconsistent system. A formal system being inconsistent implies being able to prove some statement
by clickok 8y ago
It does, insofar as you can express anything meaningful in an inconsistent system.
A formal system being inconsistent implies being able to prove some statement A, and also its converse ~A.
If both A and ~A are true, then we can prove that every other statement in this system is also true.
A quick proof:
1. A
2. A v B
3. ~A & A v B
4. B
We start with A.
The union (logical-or) of true statement (here A) and any other statement (say B) is a true statement, thus A v B.
Then we introduce another true statement, ~A, via logical-and to get ~A & (A v B), which simplifies (disjunctive syllogism) to just B.
So we have proved B, but B was arbitrary.
It could be anything, including the statement that x = y for x and y two ostensible non-equal numbers.
- coldtea 8y agoSee here for examples why such inconsistency doesn't disqualify math in toto: https://plato.stanford.edu/entries/mathematics-inconsistent/ https://plato.stanford.edu/entries/mathematics-inconsistent/