It’s possible that the owls continued to misjudge the source of sounds because their vision was permanently impaired by the lenses, and not because all owls stop using vision to locate sounds once they develop “an auditory scheme” for doing so.

The argument is about barn owls, not all owls. Regardless, the scientists never assume that all barn owls have equally good vision. Instead, they draw a conclusion about all barn owls based on a study of barn owls that were given lenses from birth to maturity.

The scientists never argue that the owls use human reasoning. Instead, they hypothesize about the owls’ process of locating sounds.

The scientists’ hypothesis is only about how barn owls locate sounds. It doesn’t matter how the lenses might affect other bird species’ behavior.

The scientists do use experimental results as evidence, but those results are relevant because they’re directly related to the conclusion.