Why does Goku give up against Cell? During the Cell games, Goku knew he wouldn't be able to defeat Cell. But it's unlike a Saiyan to ever give up. Goku didn't give up when he fought Vegeta, or Freiza, or anyone else for that  matter. But why does he give up against Cell? This isn't consistent with Goku's character.
Because he knew someone who could defeat Cell - his son, Gohan.

He knew for certain that his son Gohan would be able to defeat Cell, and so the fate of the world wouldn't 100% depend on Goku. And so, after tiring Cell for a bit, he gave up to allow Gohan to battle.