Here is an argument against the idea that there can exist a "theory of everything". Consider the trivial true and false theories, which explain every fact about the universe, the universe being defined as all those things (events,entities,etc.) that exist/that can be a cause: Trivial true: everything in the universe is caused by something(s) inside the universe. Trivial false: everything in the universe is caused by something(s) outside the universe. As can be seen, both "theories" have explenatory power equal to zero, and are just each other's complement. Any real theory though should have an explenatary power greater then zero, or would be meaningless. This would mean for such a theory, it could not explain all facts or be wrong.