In an interview with Joseph Gelmis in 1969, director Stanley Kubrick said that “[HAL] had an acute emotional crisis because he could not accept evidence of his own fallibility.” This is suggested by HAL’s assertion that no error has ever been made by a computer of his kind, even though the crew believes he has done just that.

However, some believe HAL’s breakdown was brought on by earlier problems. Both the film’s sequel, 2010, and early drafts of the script suggest that authorities on Earth ordered HAL to withhold information from the astronauts regarding the true purpose of their mission. Some argue that doing so went created a conflict with HAL’s basic programming, resulting in a gradual failure that led to his homicidal actions against the crew. To support this theory, some point out that HAL immediately misdiagnoses the hardware failure on the ship after he asks Bowman if he is disturbed by the “mysteries” and “secrecy” around the mission.