I was watching the season finale of Person of Interest, “Firewall” and an interesting point came into mind. Although the episode was not about this point, the scenario reminded me of the Unstoppable Force Paradox. In Chinese, there is an idiom, “自相矛盾”.
* Spoiler warning provided in article *
The Chinese idiom means self-contradictory. The story is from Zhou Dynasty (1046–256 BC).
In the State of Chu, there was a weapon peddler selling spear and shields. He calls out to the crowd, “My shields are so strong, they cannot be penetrated by any weapon.” And he calls out to the crowd, “My spears are so sharp, they can pierce any shield.” A passerby asks him, “What happens when your spear is thrown at your shield?” The peddler was tongue tied and could not respond.
Let’s run it thru a logical proof.
Let A = There exists a spear that can pierce any shield
Let B = There exists a shield that no spear can pierce
Given: A → ¬B
Prove: A ∧ B
A ∧ B
¬B ∧ B, modus ponen
But it is interesting to ponder the existence of the impenetrable shield and the all-piercing spear whether they exist or not. And whether they would annihilate each other in a singularity.
Now back to our story.
* SPOILER ALERT *
As a piece of back story in the episode of Person of Interest, hacker and software genius, Harold Finch, creates a system so secure that he himself cannot crack into. At the time of the system’s creation, he was asked to create a backdoor to the system. His response was that any vulnerability would mean the system is vulnerable.
The episode was not about Mr. Finch’s abilities as a hacker or software genius. And the episode barely touched on the irresistible force paradox, but I’m sure this would be an interesting point to explore in future episodes.
In the meantime, we can ponder the philosophical question, “If god is so powerful, then can he create a rock so heavy he himself cannot lift?”