And if he doesn't give a good explanation for why he changed his mind, he is still a liar. Absurd analogy but let's run with it anyway. Suppose you're meant to be working through the night and the only reason you were allowed to go home in the first place was because you promised your entire firm that you would go straight to bed. They have a vote and, based upon your promise they let you go home. You then turn up the next day without a single bit of you hanging the right way and, as far as they can tell, one of your extremely rich buddies persuaded you to stay out all night at a strip club. (They've seen this type of behaviour before - the last five guys that had your job were always making promises they didn't keep too, usually because some rich buddy had their ear.) If you don't assuge them of this misconception then, as far as they are concerned, you are indeed a liar.
