Carl Sagan's Imaginary Dragon
In The Demon-Haunted World : Science as a Candle in the Dark (1997), Carl Sagan imagines that he has offered to show me a fire-breathing dragon in his garage, and, when I get there, I see only "a ladder, empty paint cans, and an old tricycle." He'd neglected, it seems, to mention that the dragon is invisible. This thought experiment imagines my proposing a series of ways to detect the dragon. They are good ideas, he imagines replying, but unfortunately won't work. Flour on the floor won't because dragons levitate, infrared won't because dragon fire is heatless, and spray paint won't because dragons are incorporeal. If Sagan insists on countering every test I propose with an evasive redefinition, it's clearly silly for him to then shift the burden of proof onto me and suggest that, since I can't prove the dragon is absent, it may very well be present. There's no practical difference between an undetectable dragon and no dragon at all. ...