came up with this* possible world
story to try to show that humans could be responsible for their actions even if they did not have free will
Sid wants the king dead.
So he comes up with a Cunning Plan--next time he sees the king, he'll shoot him.
But before he goes after the king, he visits his dentist for a root canal. Unknown to Sid, his dentist is an Evil Genius. While Sid is under general anesthesia, his dentist hooks him up to the Evil Computer, which reads his mind. Once informed of Sid's Cunning Plan, the dentist quickly summons a minion, bidding him to construct a behavior monitor/controller. He then proceeds to implant this device in Sid's brain. The dentist, you see, also wants the king dead, and he isn't going to take the chance of Sid chickening out at the last moment.
The next day, Sid is walking along, when all of a sudden he sees the king strolling through the park across the way. He quickly dodges behind a dumpster, checks his gun, and waits for a clear aim.
Meanwhile, the Evil Dentist has been alerted by his Evil Computer that Sid is ready to make his move. They are monitoring him closely.
Sid hesitates momentarily, and then pulls the trigger.
The king's head explodes into a million gory bits.
Most people would say that Sid is guilty of regicide.
But he could hardly have done otherwise -- the Evil Dentist would have made him shoot the king anyway. He is merely a puppet in this game in intrigue.
It would seem that Sid is a Bad Person even though he didn't have any choice in his action.
People have found problems with this, my favorite being that Sid did make a free choice to kill the king -- it was only his actions, not his beliefs that were determined. If this had been a truly deterministic system, Sid would have had no choice in his beliefs.
*Not actually this story -- if I come across the original, I'll post it. This is the same basic idea, tho.
See determinism, predeterminism, and free will.