I met a white man who walked a black dog
This is most likely a reference to
Arthur Schopenhauer, who had many poodles in his life; He assigned them all the same name (atma or “world soul”) He habitually went on walks much like one of his mentors; Kant.
Nietzsche’s mentor was Arthur Schopenhauer and the previous line is about Nietzsche.
But it also has the quality of being a commentary on race, which would be very typical of Dylan’s work. Here the narrator is saying that he has seen African Americans lowered down to the status of dogs and led around by the whites who have greater control over society.
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