This is unresolvable. You may well think that Alice is lying. Your friends may be certain that Alice is lying. But there are plenty of other explanations, and it's completely possible that Alice is sincerely holding on to her conviction. Remember that your unconscious biases are very likely to influence your assessment of what someone else might be thinking.

Alice may completely disagree with your assessment, and she's in no way obliged to respond to Bob in the original thread. She would be right to disagree, too, since Bob's method can be used to prove that the sky is red, purple, orange, black, and if you insist - green.


The average colour of the sky here is (52, 84, 37) - indeed, Bob's method proves the sky is green under certain circumstances.

An unfinished conversation is not a concession on anyone's part.

The rules don't prohibit you from accusing someone of lying. Of course, it's unlikely to advance the conversation, but if you've reached the point where you suspect someone is openly lying to you, then the conversation is probably not advancing either way. My personal recommendation would be to back away and stop arguing with someone you find dishonest - but I've also been guilty of not doing that before.

What are the circumstances that earth is flat?