JW: The proof of the existence of God lies in everything around you. Flowers, bees, people and trees are all so obviously the product of an intelligence, and that intelligence could only be god.

Me: Aha - but we have this brand, spanking new idea, called evolution by natural selection. The appearance of intelligent design in everything you see around you is a form of illusion - it actually took place over millions of generations of incremental change.

JW: An illusion? But surely the good god would not allow us to be so deceived!

Me: Aha - that's assuming the antecedent a/k/a petitio principi a/k/a begging the question, that is.

KW: You bleating whinger.

Curtain, to rapturous applause



edit

And, as far as I am aware, the roots of the phrase lie in legal type terminology. To 'beg the question', as Faldage's Latin suggests, is to beg (ie plead for) the matter in question (ie the subject of the dispute), as opposed to making a case for it. Eg: Mink and Monk have a land dispute - boundary lines et al and go to court. Mink says "I have here records from the last few generations showing that the strip of land in dispute has always belonged to my family." Monk says "But that can't be so!". "Why?" "Because that land is mine. {sotto voce "God gave this land, to meee...}" "You may think so," says, Mink, exasperated. "But that is, in fact, what we're here to discuss. Your claim is not an argument. You're begging the ruddy question!"

And so it goes...