It is difficult to establish precisely what Boo Radley's motivation is in the novel, as we know very little about him, and what we do know we learn about indirectly. However, we do know that he is extremely lonely and isolated, and he cannot relate normally to other people. His main motivation seems to be a desire for friends and company, and a desire to be liked. This is supported by the fact that Boo Radley seems to be very innocent and kind, and that he never does anything to purposely hurt anyone.