(n.) The quality or state of being irrational.

Urdummheit aberration abnormality alienation antilogy brain damage brainlessness brainsickness callowness childishness clouded mind craziness daftness dementedness dementia derangement disorientation distraction folie foolishness furor ignorance illogic illogicality illogicalness immaturity imprudence inadvisability inattention incapacity inconclusiveness incongruity inconsideration inconsistency indiscreetness indiscretion ineptitude inexpedience injudiciousness insaneness insanity invalidity lackbrainedness lackwittedness loss of mind loss of reason low IQ lunacy madness mania mental deficiency mental derangement mental disease mental disorder mental disturbance mental illness mental instability mental sickness mental weakness mind overthrown mindlessness mindsickness oddness pixilation pompousness possession primal stupidity puerility queerness rabidness reasonlessness recklessness senselessness shattered mind sick mind sickness slackmindedness slackwittedness strangeness stuffiness thoughtlessness unbalance unbalanced mind unintellectuality unintelligence unreason unreasonableness unsaneness unscientificness unsensibleness unsound mind unsoundness unsoundness of mind untenableness unthoughtfulness unwisdom unwiseness witlessness