[Goku hesitates for a second- he doesn't seem like that kind of guy. He doesn't think he is that kind of guy. But he knows that he can do terrible things, if there's no one there to stop him.]

... I dunno. But- well, who'd lock a kid up like that for that long for no reason? They weren't using me for anything. [Goku knows there are terrible people in the world, sick people who take pleasure in hurting others. But he doesn't think that was the case with him.] When I woke up in the cave, I didn't remember anything. Not how I got there, or anyone I'd known before. The only thing I remembered was my name and- [and the horrible feeling that he'd lost something.] ... and that was it.

Until Sanzo found me, I wasn't even sure there was anyone else in the world.