I have had some discussions with parents about honesty. I know at least two sets of parents who adamantly insist that they never lie to their children. They may hold back some of the truth (and some might call that a lie of omission) but they never willfully tell their kids a fib, and that includes Santa, my favorite childhood fiction.
To be clear, LW and I do not lie to the boy in some off hand manner. He is getting the hang of leg pulling, knowing that maybe I do not actually have first hand knowledge of the War of the Roses. But jesting I do not count in the same world as lying. But there is something that I treasure, perhaps it is selfish, in keeping the boy believing in Santa Claus.
The world is a crazy place, and frequently truth is stranger than fiction, and harder to explain. I try to be frank and open with the boy when he asks a question (unless, as stated before, I am making some far fetched claim to help improve his sense of humor). Children have the world crashing in on them more and more rapidly what with the easily accessible and constant information. As a shield against this imminent loss of innocence, I give him Santa Claus, a benevolent elf.
I have other reasons for pushing the fiction. The Boy is fact obsessed. A book on human anatomy holds more interest for him than the works of C.S. Lewis. Watching the movie FROZEN, while he did enjoy it in general, there were times he was noticeably frustrated at things depicted on screen which he pointed out were impossible.
There is an innocence in fiction, and fiction can be seen as lies. Soon enough, he will know (or admit to already knowing) that Santa Claus as an actual person is a fib. But education is more than just science, math and empirical evidence. It is also art and literature and beauty that is inexplicable. And if I can bring the Boy into my fantasy world, even just a little, I will consider it time well spent.