Leading up to a 75th anniversary theatrical viewing of The Maltese Falcon, I've been re-watching Huston's classic adaption and re-reading Hammett's novel. It remains a favorite, though I see through different eyes now that I'm about the age of Spade's ill-fated partner, Miles Archer, than I did when I read and watched it repeatedly as a bookish pre-teen who had just discovered film noir and the novels of Hammett and Chandler.
What's in a name? It's possible I've read too much into "La Paloma" as the name of Jacobi's ship already, so might as well speculate on the name Jacobi itself.
It strikes me as an apt name to use for a minor character in a detective novel. I can only speculate as to how Hammett landed on it, but I'd like to think it's a nod to the German mathematician Carl Gustav Jacob Jacobi:
"It was in algebraic development that Jacobi’s peculiar power mainly lay, and he made important contributions of this kind to many areas of mathematics, as shown by his long list of papers in Crelle’s Journal and elsewhere from 1826 onwards. One of his maxims was: 'Invert, always invert' ('man muss immer umkehren'), expressing his belief that the solution of many hard problems can be clarified by re-expressing them in inverse form."Detectives, after all, face hard problems, so how to think about solving problems would be a matter of some importance to them. The clues don't add up? Try reasoning by subtraction. Invert the problem and see if expressing it in different terms leads to insight.
To figure out who killed Archer, he's got to look at the problem outside the narrative O'Shaughnessy has fed him. He's got to see how it doesn't add up. O'Shaughnessy must be lying when she says she couldn't trust Thursby. Spade learns that Thursby's loyalty to her was unshakable. Miles may have been a fool, but he was too experienced a detective to be gunned down by a man he was tailing without getting his hands out of his pockets. "The man who shot him stood here," Archer says when re-enacting the shooting with Tom Polhaus. That a man did it is an assumption based on facts not in evidence. Spade's got to recognize the lazy thinking and subtract anything that followed from the false premise. He figures out while he and O'Shaughnessy await the inevitable arrival of the police after Gutman's gang have left his apartment to skip town. Jacobi, the mathematician, would have been proud. (Jacobi, the bullet-ridden ship's captain, would have liked to have know the sort of woman O'Shaughnessy was before falling in with her.)