# Harry Potter and the Methods of Rationality

Harry Potter and the Methods of Rationality (HPMOR) is a work of Harry Potter fan fiction by Eliezer Yudkowsky published on FanFiction.Net as a serial from February 28, 2010, to March 14, 2015, totaling 122 chapters and over 660,000 words. It adapts the story of Harry Potter to explain complex concepts in cognitive science, philosophy, and the scientific method. Yudkowsky's reimagining supposes that Harry's aunt Petunia Evans married an Oxford professor and homeschooled Harry in science and rational thinking, allowing Harry to enter the magical world with ideals from the Age of Enlightenment and an experimental spirit. The fan fiction spans one year, covering Harry's first year in Hogwarts. HPMOR has inspired other works of fan fiction, art, and poetry.

## Plot

In this fan fiction's alternate universe to the Harry Potter series, Lily Potter magically made her sister Petunia Evans prettier, letting her marry Oxford professor Michael Verres. They adopt their orphaned nephew Harry James Potter as Harry James Potter-Evans-Verres and homeschool him in science and rationality. When Harry turns 11, Petunia and Professor McGonagall inform him and Michael about the wizarding world and Harry's defeat of Lord Voldemort. Harry becomes irritated over wizarding society's inconsistencies and backwardness. When boarding the Hogwarts Express, Harry befriends Draco Malfoy over Ron Weasley and teaches him science. Harry also befriends Hermione Granger over their scientific inclinations.
At Hogwarts, the Sorting Hat sends both Harry and Hermione to Ravenclaw and Draco to Slytherin. As school begins, Harry earns the trust of McGonagall, bonds with Professor Quirrell (who strives to resurrect the teaching of battle magic) and tests magic through the scientific method with Hermione. Harry invents partial transfiguration, which transmutes parts of wholes by applying timeless physics. Draco reluctantly accepts Harry's proof against the Malfoys' bigotry against muggle-borns and informs him that Dumbledore burned his innocent mother, Narcissa, alive.
After winter break, Quirrell procures a Dementor to teach students the Patronus charm. Though Hermione and Harry initially fail, Harry recognizes Dementors as shadows of death. He invents the True Patronus charm, destroying the Dementor. After Harry teaches him to cast a regular Patronus, Draco discovers Harry can speak Parseltongue. Quirrell reveals himself as a snake Animagus to Harry and convinces him to help spirit a supposedly manipulated Bellatrix Black from Azkaban, exposing Harry to the horrors of prisoners while Dumbledore believes that Voldemort is back. After a confrontation, he tells Harry that the Order of the Phoenix made him murder Narcissa to stop Voldemort from taking hostages.
Hermione establishes the organization S.P.H.E.W. to protest misogyny in heroism and fight bullies. This causes widespread chaos, and the group's activities are put on pause. She and Draco are manipulated into believing she attempted the murder of the latter, and Harry pays his fortune to Lucius Malfoy to save Hermione from Azkaban. A surprised Lucius accepts and withdraws Draco from Hogwarts. The wizarding world theorize that Quirrell is David Monroe, a long-missing opponent of Voldemort. A mountain troll enters Hogwarts and kills Hermione before Harry manages to kill it. Grieving, Harry vows to resurrect Hermione and preserves her body. Harry absolves the Malfoys of guilt in Hermione's murder in exchange for Lucius returning his money, exonerating Hermione, and returning Draco to Hogwarts.
Quirrell starts eating unicorns, supposedly to delay death from a disease. Near the end of the year, he captures Harry, revealing himself as Voldemort's spirit possessing Quirrell and how he framed and murdered Hermione by proxy. He coerces Harry into helping him steal the Philosopher's Stone, an artifact for performing true transmutation as transfiguration is otherwise temporary, by promising to resurrect Hermione. They succeed when Dumbledore appears and tries to seal Voldemort outside time. Voldemort endangers Harry, forcing Dumbledore to seal himself instead.
Voldemort's spirit abandons Quirrell and embodies using the Stone; he and Harry resurrect Hermione with the power of the Stone and Harry's True Patronus. Voldemort murders Quirrell as a human sacrifice for a ritual to give Hermione a Horcrux and the superpowers of a mountain troll and unicorn, rendering her near-immortal. Knowing Harry is prophesied to destroy the world, Voldemort holds Harry at gunpoint, strips him naked, summons his Death Eaters, forces Harry into a magical oath to never risk destroying the world, and orders his murder. Harry improvises a partial Transfiguration into carbon nanotubes that beheads every Death Eater and maims Voldemort. He stuns, memory-wipes, and transfigures him into his ring's jewel. Harry claims the Stone and stages a scene looking like "David Monroe" died defeating Voldemort and resurrected Hermione.
After the battle, Harry receives Dumbledore's letters, learning Dumbledore gambled the world's future on him due to prophecies and let Harry inherit his positions and assets. Harry helps a grieving Draco find his mother, Narcissa, and plans with the resurrected Hermione to overhaul wizarding society by destroying Azkaban with the True Patronus and using the Philosopher's Stone to grant everyone immortality.

## History

Yudkowsky wrote Harry Potter and the Methods of Rationality to promote the rationality skills he advocates on his community blog LessWrong. According to him, "I'd been reading a lot of Harry Potter fan fiction at the time the plot of HPMOR spontaneously burped itself into existence inside my mind, so it came out as a Harry Potter story, [...] If I had to rationalize it afterward, I'd say the Potterverse is a very rich environment for a curious thinker, and there's a large number of potential readers who would enter at least moderately familiar with the Harry Potter universe."
Yudkowsky has used HPMOR to assist the launch of the Center for Applied Rationality, which teaches courses based on his work.
Yudkowsky refused a suggestion from David Whelan to sell HPMOR as an original story after rewriting it to remove the Harry Potter setting's elements from it to avoid copyright infringement like E. L. James did with Fifty Shades, which was originally a Twilight fan fiction, saying, "That's not possible in this case. HPMOR is fundamentally linked to, and can only be understood against the background of, the original Harry Potter novels. Numerous scenes are meant to be understood in the light of other scenes in the original HP."
After HPMOR concluded in 2015, Yudkowsky's readers held many worldwide wrap parties in celebration.

## Reception
### Critical response

Harry Potter and the Methods of Rationality is highly popular on FanFiction.Net, though it has also caused significant polarization among readers. In 2011, Daniel D. Snyder of The Atlantic recorded how HPMOR "caused uproar in the fan fiction community, drawing both condemnations and praise" on online message boards "for its blasphemous—or brilliant—treatment of the canon." In 2015, David Whelan of Vice described HPMOR as "the most popular Harry Potter book you've never heard of" and claimed, "Most people agree that it's brilliantly written, challenging, and—curiously—mind altering."
HPMOR has received positive mainstream reception. Hugo Award-winning science fiction author David Brin positively reviewed HPMOR for The Atlantic in 2010, saying, "It's a terrific series, subtle and dramatic and stimulating… I wish all Potter fans would go here, and try on a bigger, bolder and more challenging tale." In 2014, American politician Ben Wikler lauded HPMOR on The Guardian as "the #1 fan fiction series of all time," saying it was "told with enormous gusto, and with emotional insight into that kind of mind," and comparing Harry to his friend Aaron Swartz's skeptical attitude. Writing for The Washington Post, legal scholar William Baude praised HPMOR as "the best Harry Potter book ever written, though it is not written by J.K. Rowling" in 2014 and "one of my favorite books written this millennium" in 2015. In 2015, Vakasha Sachdev of Hindustan Times described HPMOR as "a thinking person's story about magic and heroism" and how "the conflict between good and evil is represented as a battle between knowledge and ignorance," eliciting his praise. In 2017, Carol Pinchefsky of Syfy lauded HPMOR as "something brilliant" and "a platform on which the writer bounces off complex ideas in a way that's accessible and downright fun." In a 2019 interview for The Sydney Morning Herald, young adult writer Lili Wilkinson said that she adores HPMOR; according to her, "It not only explains basically all scientific theory, from economics to astrophysics, but it also includes the greatest scene where Malfoy learns about DNA and has to confront his pureblood bigotry." Rhys McKay hailed HPMOR in a 2019 article for Who as "one of the best fanfics ever written" and "a familiar yet all-new take on the Wizarding world."
James D. Miller, an economics professor at Smith College and one of Yudkowsky's acquaintances, praised HPMOR in his 2012 book Singularity Rising as an "excellent marketing strategy" for Yudkowsky's "pseudoscientific-sounding" beliefs due to its carefully crafted lessons about rationality. Though he criticized Yudkowsky as "profoundly arrogant" for believing that making people more rational would make them more likely to agree with his ideas, he nonetheless agreed that such an effort would gain him more followers.

### Accolades

The HPMOR fan audiobook was a Parsec Awards finalist in 2012 and 2015.

## Translations
### Russian

On July 17, 2018, Mikhail Samin, a former head of the Russian Pastafarian Church who had previously published The Gospel of the Flying Spaghetti Monster in Russian, launched a non-commercial crowdfunding campaign hosted on Planeta.ru alongside about 200 helpers to print a three-volume edition of the Russian translation of Harry Potter and the Methods of Rationality. Lin Lobaryov, the former lead editor of Mir Fantastiki, compiled the books. Samin's campaign reached its 1.086 million ₽ (approximately US$17 000) goal within 30 hours; it ended on September 30 with 11.4 million ₽ collected (approximately US$175 000), having involved 7,278 people, and became the biggest Russian crowdfunding project for a day before a fundraiser hosted on CrowdRepublic for the Russian translation for Gloomhaven surpassed it.
Though Samin originally planned to print 1000 copies of HPMOR, his campaign's unprecedented success led him to print twenty-one times more copies than that. Yudkowsky supported Samin's efforts and wrote an exclusive introduction for HPMOR's Russian printing, though the campaign's popularity surprised him. Samin's HPMOR publication project is the largest-scale effort on record, surpassing many previous low-circulation fan printings, and he sent some Russian copies of HPMOR to libraries and others to schools as prizes for Olympiad winners. J.K. Rowling and her agents refused Russian publishing house Eksmo's request for commercial publication of HPMOR.

### Other

HPMOR has Czech, Chinese, French, German, Hebrew, Indonesian, Italian, Japanese, Norwegian, Spanish, Swedish, and Ukrainian translations.