Kantian ethics says that One must always tell the truth, similar to the Radicle Honesty. I think the simplest rebuttle to this is: If an ax murder shows up, ax in hand, at your door step and asks where your friend is, and you know where your friend is because they are in your house, then I must tell the murder where they are. Certainly, it would seem, life is important, and perhaps in this instance I think that life is more important then truth. We don't only have the duty of truth telling: we also have a duty to life, I feel that Where we can save a life we aught not to tell the truth if the truth would directly lead to the death of someone. Thus we have the duty to learn to lie, and thus save lifes.