Ipso facto is a Latin phrase, directly translated as "by the fact itself", which means that a specific phenomenon is a direct consequence, a resultant effect, of the action in question, instead of being brought about by a previous action. It is a term of art used in philosophy, law, and science. (Contrast this with the expressions "by itself" or "per se".)

Aside from its technical uses, it occurs frequently in literature, particularly in scholarly addenda: e.g., "Faustus had signed his life away, and was, ipso facto, incapable of repentance" (from Christopher Marlowe, The Tragical History of Dr. Faustus) or "These prejudices are rooted in the idea that every tramp ipso facto is a blackguard" (from George Orwell, Down and Out in Paris and London). Its use is also found in rabbinic writings: "If a man sells a house, he ipso facto sells with it the door."