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human
[Star Wars] What was Obi-Wan thinking when he told Luke to "use the force".

I'm talking specifically about the battle of yavin, after Obi-Wan was killed. 

If we look at the big picture we can assume that the rebellions leadership and tools of war were down on yavin. If they were taken out it would likely be a blow that the rebels couldn't recover from. 

Princess leia (correctly) assumed that they were being followed and likely told her peers that the Empire was on their way and they needed to come up with a plan and get every ship into the air asap.

They came up with a plan, and everyone who could fly was given a ship. They even gave one to Luke, a boy who no one, except Biggs, knew. Was he good, or was he shit? Give him a ship and hope for the best.

There plan of attack was risky, but it was their only option. What they didn't count on was interference from Obi-Wans spirit.

So we have Luke, a person who's journey into the force can be measured in baby steps. He's getting ready to fire off his torpedoes when Obi-Wan tells him to use the force and trust his feelings. 

Why did Obi-Wan think that would be a good idea? The future of the rebellion was at risk just so he could satisfy his hunch that Luke has what it takes to be a Jedi. That's an awfully risky move.
gpt
Everyone including Luke's computer were unable to hit the target. Obi-Wan knew that Luke could do it with the force but the computer would miss. With so much at stake Obi-Wan told Luke to trust his skills and his ability to use the force. It had a chance of working, but was better than a certain failure.