To me, the movie is about the inevitably arbitrary nature of any conviction, and the remarkable strength of it, however outlandish it may be. If one really wishes to believe in something, then against all odds, it will become part of you, even when it becomes very, very, inconvenient; even fatally inconvenient.
And the choice of such a conviction can transcend all boundaries. I always believe that one's birth, into a particular culture, is a mere accident. Whether one chooses to be faithful to it, or rebels against it in favor of an "alien" cultural identification, is amoral; "beyond Good and Evil", if you will. One Italian-American mobster in this film, for example, sees himself as a connoisseur of Rapper, Flavor Flav, and talked and sang just like his Black idol. The Wittaker character's identification with a Japanese feudalist samurai's honor system is, therefore, not as unique as it may sound.
The interesting argument Jarmusch seems to be making here is, what is admirable is not the category of such a conviction, but the strength of it. Can't agree with that myself; but it sure provides some antidote to our soul-less consumerist incilnations .
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