 Broadly speaking, thought experiments use imaginary scenarios to elicit responses that (ideally) grant people knowledge of possibilities. A special, but prominent, type of thought experiment in philosophy concerns the link between imagination, conceivability, and metaphysical possibility. René Descartes famously offered a modal argument in the Sixth Meditation, reasoning from the fact that he could clearly and distinctly conceive of his mind and body as distinct to the real distinctness between them. The current prevalence of similar modal arguments can be verified by entries on  zombies  and  dualism.  These modal arguments all rely, in some way, on the idea that what one can imagine functions as a fallible and defeasible guide to what is really possible in the broadest sense.