This made it click for me. My interpretation is:
(P → Q) could be true while P is false, or while P is true (and Q is true).
The assertion (P → Q) → P is saying “if (P → Q), then it’s the ‘P is true’ version.”
It can’t be the ‘P is true’ version if P is false. Therefore P is true.
(This requires grokking the fact that not-P instantly makes (P → Q) true, regardless of the value of Q.)
This made it click for me. My interpretation is:
(P → Q) could be true while P is false, or while P is true (and Q is true).
The assertion (P → Q) → P is saying “if (P → Q), then it’s the ‘P is true’ version.”
It can’t be the ‘P is true’ version if P is false. Therefore P is true.
(This requires grokking the fact that not-P instantly makes (P → Q) true, regardless of the value of Q.)