Once in the wardrobe, the Pevensie children notice almost immediately that they have entered the world of Narnia. Together they set out to explore the snowy wood. On the way, Edmund admits that he has been in Narnia before, and everyone is furious with him. Lucy leads the group to Tumnus's home, but when they get there, they find that it has been ransacked. A note on the floor informs all visitors that Tumnus has been taken away on charges of treason. Lucy understands immediately that this means the Witch has discovered that Tumnus spared her life. Lucy implores the others to help her rescue Tumnus, and everyone except Edmund agrees. Since Edmund is outvoted, they continue on to save the faun. They do not know where they are going, but a robin leads them to the middle of the wood. Peter, Susan, and Lucy believe that the robin is friendly, but Edmund whispers to Peter that the robin may be on the wrong side, and leading them into a trap. Edmund contends that they do not even know which is the wrong side and which is the right. He also points out that they now have no idea how to return home, which troubles Peter greatly.
Edmund's warning that the robin may be evil is hard to rebuff because it is perfectly reasonable. How can the children know for sure that the robin is on their side? For that matter, how are they to know which side is right and which side is wrong? Edmund's protest reflects the logical, fact-oriented mindset of the twentieth century, in which people are more inclined to trust hard facts than their own emotions. This modern faith in reason is a departure from the pre-modern era, when people did not always require facts and evidence to believe in things. For example, people believed in the Bible without demanding proof that Jesus actually lived and performed miracles. Lewis was well-known as a Christian apologist—someone who struggled to logically prove the existence of a Christian God. Of course, he could never prove the existence of God in the sense of providing hard facts to demonstrate God's existence. His arguments were brilliant from a philosophical standpoint, but it is impossible to banish all doubt from the heart of a devoted skeptic who demands purely scientific evidence.
By asking for proof that the robin is a friend, Edmund represents what Lewis dislikes about the twentieth century's rational, skeptical mindset. Peter argues, "Still—a robin, you know. They're good birds in all the stories I've ever read. I'm sure a robin wouldn't be on the wrong side." Peter's statement appears weak and unconvincing compared to Edmund's because it is not based in fact. Edmund further invalidates Peter's words by pointing out that they do not even know whether the Witch, or Queen, is the wrong side. The reader, however, can see that Edmund's seemingly rational viewpoint is actually tainted by his greed for the Turkish Delight. He is not unbiased, as he claims, but quite the opposite. Nevertheless, his argument is hard to refute.
The problem of how to know who is good and who is evil does not just apply to the children in the novel, but might equally be posed to the reader. How can the reader know for sure whether the Witch is really evil and Tumnus really good? We do not really have any more evidence than the children, but we feel that we know intuitively who is good and who is evil. We simply trust that the world has not been turned upside-down, that the faun isn't playing an elaborate prank on Lucy, and that we can trust our instincts. Edmund's question brings up a very important point—it is very hard to prove anything completely and objectively. Edmund argues that even though the faun said he saved Lucy, they have no way of knowing whether this is true. No matter how much evidence there is that the faun saved Lucy, someone else could always construct an elaborate argument that things are not what they seem, and it would be impossible to prove the faun saved her without a doubt.
Lewis's message is that we have to follow our instincts, and if they lead us into trouble, we will be no worse off than if we had cowered on the sidelines. If the children had not followed the robin, they would still be standing in the wood, unable to commit to any plan of action. This applies to a person's faith in Christianity. Blind faith is at the core of any fervent belief in Christ, as there is no way to logically prove the existence of God. Yet, more generally, Lewis may be cautioning against allowing skepticism and doubt to overwhelm our beliefs. Edmund indulges in this type of doubt when he finds himself morally trapped by his allegiance to the Witch. Edmund's doubt is a defense mechanism that inhibits him from acting. Moreover, Edmund has an ulterior motive to his skepticism. He wants to believe that the Witch is not really a Witch after all, because he of his overpowering desire for Turkish Delight. We see from Edmund's example that skepticism can go from being a means to an end to being an end in itself, resulting in stagnation. Peter, on the other hand, knows instinctively that he should trust the robin, even though he cannot logically explain why. As it turns out, Peter is correct.