Thanks for the info on it, it is a common colloquialism in my region, the US south east. I was using it, in what is described as the modern usage in the link that was provided in one of the other posts. I did not know that it was used as a term to describe a logical fallacy. It's usage in my region could be inferred to mean: It is an important question that should be asked and not that it assets that the sentence to follow is true.