The Voight-Kampff test fails because it mistakes the symptom for the proof.
Deckard leans toward Rachel with his device, watching her pupils dilate, her respiration spike, her tear ducts engage—physical betrayals he assumes consciousness must produce.
But the film's central disaster isn't that replicants learned to fake tears. It's that Tyrell engineered them well enough that their emotional responses became neurologically identical to human ones—which means the test was measuring nothing but the examiner's willingness to trust a machine designed to measure trust.
Watch the Rachel sequence: she doesn't pass because she's human. She passes because Tyrell built her emotions so thoroughly that separating the real response from the performance became a category error. The needle moves the same way.
The question dissolves.
Watch the 1982 theatrical cut's final scene with the elevator doors and Deckard's unicorn thought-flash, then read Philip K. Dick's 1968 novel 'Do Androids Dream of Electric Sheep?' side-by-side to see how Scott deleted the novel's entire epistemological framework and replaced it with visual ambiguity about interiority.
Sean Young's 1999 interview for 'Blade Runner: The Dangerous Edition' DVD commentary, where she discusses how Ridley Scott deliberately kept her uncertain about Rachel's ontological status during filming—a directorial choice that mirrored the test's own inability to deliver certainty.