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Harry Potter and the Methods of Rationality by Eliezer Yudkowsky, is a well known Harry Potter fanfic, published on and This tag is for all questions pertaining to this work. Always use in conjunction with the [harry-potter] tag.

Harry Potter and the Methods of Rationality, commonly abbreviated as HP:MoR, is a famous fanfiction by noted AI researcher and owner of 'Less Wrong' rationality blog Eliezer Yudkowsky.

The fanfiction is parallel (alternate) universe; with the main premise being that Harry was raised in a scientific household; and upon entering Hogwarts, applies scientific method and rationality to discovering the universe's magic.

The official website for the fanfiction is located at, and includes authors notes, fan art, links to fan-fanfiction and update notices.