In medical jurisprudence. An insane delusion is an unreasoning and incorrigiblebelief in the existence of facts which are either impossible absolutely, or, atleast, impossible under the circumstances of the individual. It is never the result ofreasoning and reflection; it is not generated by them, and it cannot be dispelled bythem; and hence it is not to be confounded with an opinion, however fantastic thelatter may be. Guiteau’s Case (D. C.) 10 Fed. 170. See INSANITY.