The Devil's Advocate
Call me Dad
You rob a bank and getaway. I come to your house and say, "hey I saw you rob that bank and I have video. Give me half or I'm turning you in. And if I don't show up tomorrow, it's going to the cops anyway."OK, shouldn't he make dude prove it? He doesn't have the evidence he was claiming.
Now how exactly will you force ANYTHING?
Beat me/torture me and I might say I was bluffing... Am I though? Can you sleep trusting that you're not gonna be on the news tomorrow? You 150% I told you the truth?
Or I might just die and say nothing... You stuck in the same situation.
Or I might tell you it's in the bank... You can't walk me into there now can you? And unless you do, you still have no idea if it's really even in there or not. I could just be lying to stop the torture....
You could torture me to give up the location and then kill me and then go yourself... but you run into all the same problems............
See that's where blackmail works. The person being blackmailed is fearful of the what ifs. THEY know they did wrong.. And now they know YOU know they did wrong.. The only thing they care about, is nobody else finding out. And mutually assured destruction is the only true way both sides can agree. I mean even if I handed you "all" the evidence, how are you sure there's not more?