The Truth.

As for kids, I've always believed in full disclosure. They need to understand that the world is dangerous, and that the biggest danger is not believing in them. They require an understanding of whats out there, what they can do to protect themselves, and what they can do if they find themselves in a situation they couldn't avoid, then they need to get out there and live life hoping to never need the alternative plans but being fully ready to do so.

I think we're thinking about different scenarios. What I mean, is that you don't directly tell them with words that the world is a dangerous and harmful place when you get a child. By moving to the suburbia, you say to your child that the world is quite, warm and safe: The environment you want to create for a newborn child will be quite unlike the streets of a big city. It's certainly not a bad lie to tell, to give a baby the impression the world is quiet and warm and safe. But, as you point out, this harmless type of lie can turn sour if left unexamined.

Imagine if you tried to keep someone in as protected an environment as a newborn till age 18. To mislead someone so grossly about the world would seem not protection but abuse. That's an extreme example, of course; when parents do that sort of thing it becomes national news.

(Keep in mind that parents don't try to lie: Misleading the child is just a byproduct of protecting it.)

As for the Kantonian scenario, I would've dialed 911 the minute a bloody man ran by, and likely pursued him, making the scenario itself unlikely. I've never understood why people immediately fall into the role of passive witness.

Most people would have done so, but that's not the point of the scenario. The point is, is telling the truth morally right if you know that it will result in the death of a human? Or, as I think, would it be better to lie, which will result in no death at all?