understanding provability

166 Views Asked by At

I am still confused about provability.

.

.

Let a statement P is, sort-of-says like this.

P: ( "X is provable" ∧ "P is provable" )

If ( X is provable ∧ P is provable ) is provable → (P is provable) is provable → P is provable

Hence,

( X is provable V P is provable ) ⊢ "P is provable"

IF (P is provable) is provable → P is provable → (X is provable ∧ P is provable) is provable

"P is provable" ⊢ ( X is provable ∧ P is provable)

Therefore,

( X is provable ∧ P is provable ) :⇔ "P is provable"

So,original statement P is sort-of-says like this

P: "P is provable"

By the Löb's theorem, P is provable.

What the error of this reasoning?