First of all you have to examine the mind of "skeptics". For them, the glass is always half empty. I have never met a single one of them, who had an open mind enough to form an interesting discussion. Usually their mind is made up, even before a thorough conclusion can be drawn. A good example of this can be derived to the fact most circle skeptics do not believe in Aliens, or anyone similar to a human being. To proclaim the circles as man made supports their agenda Aliens do not exist.