Even though the reader never explicitly learns why Mr. Radley filled in the knothole, we can infer at least two explanations for his actions. When Atticus discounts Mr. Radley’s initial explanation – that the tree is dying – Jem comes to some understanding that the reader is not privy to. It can easily be inferred that Mr. Radley is purposely keeping Boo away from the kids, or any outside influence. Jem is starting to understand that the rumors about Boo Radley are false and that he is not the monster many people make him out to be. This theory leads the reader to see Radley’s actions as malicious. Another explanation, but less plausible, could be that he is trying to protect Boo from the outside world. This inference would require the reader to see Mr. Radley as more compassionate and caring than Harper Lee makes him out to be, which is why the first reason is the most believable.