The question of just what “Film Noir” is has plagued discussions of the genre since its retrospective creation by French critics in the 1950s and 1960s. As the term pertains to “Hard Boiled” detectives, whose presence was a clear signifier in early film noir, the formal distinctions have always been weak. I think we tend to fall back on Chandler’s dismissive summary of the differences between “realism” and “Cheesecake Manor” to frame how we divide Marple from Marlowe. Chandler famously picked Hammett as the true origin of the hard-boiled school, out of all the pulp writers publishing alongside Hammett he was picked as the “Dean of the Hard Boiled School”, and that reputation relies heavily on cross-promotion of Hammett as himself a real detective. This assessment of “realism” can’t sustain any kind of detailed scrutiny, as Hammett is definitively wrong on a number of matters in his non-fiction essays on the craft of detection.
My research into Dashiell Hammett ended up focusing on the ways in which he re-purposed the “classic” formal structures of detective fiction as practiced by the likes of SS van Dyne, Agatha Christie, et al, and enshrined in the rules of the Detection Club . Raymond Chandler was fond of “doubling” his mysteries, so that a crime in the deep past was usually the key to solving a crime in the present – a technique also favoured by one Agatha Christie. Hammett’s career can be seen in some ways as as gradually succumbing to the lure of the formal approach, because Red Harvest and The Dain Curse use detective tropes without meaningful use of clues, the defining genre feature , while The Maltese Falcon uses clues to power a melodrama, before The Glass Key features a classic whodunit to motivate its gangster drama, and The Thin Man is actually a perfectly conventional whodunit.
Hammett’s work was converted into films in approximately reverse order – The Thin Man (1934), The Glass Key (1942), The Maltese Falcon (1931 & 1941), The Dain Curse (1978), and (debatably) Miller’s Crossing (1990). The Big Sleep (1942) and The Long Goodbye (1973) were transmogrified almost without important mysteries included – who killed Owen Taylor indeed ? Just as Hammett was singled out as the first “true” practitioner of the Hard Boiled school, The Maltese Falcon (1941) is commonly identified as the first “true” Film Noir. My favourite aspect of thinking about The Maltese Falcon as the first film noir is the way it was constructed in its marketing campaign, as a “story as exciting as his blazing automatics”, which is a great selling strategy for a film in which there is not a single gunshot. The Maltese Falcon is missing, or only has in relatively low levels, many of the key aesthetic and structural features identified as “Film Noir” – so-called “Dutch Angles” are used only a few times, the lighting is fairly mainstream, the good guys broadly win. Yet there is something distinctively different about it.
The lynch-pin of The Maltese Falcon is Sam Spade’s masculinity, his through-and-through toughness, the toughness that allows him to remark of his partners death “Miles had $10,000 in insurance, no kids, and a wife that didn’t like him”. He instructs the repainting of the office door straight away and as Polhouse remarks was “in too much of a hurry to look at Miles’ body”. The sense we get is not of someone whose armour of hope and optimism allows him to overcome all emotional buffets – if anything, quite the reverse, someone so inured to the school of hard knocks that he doesn’t even notice any more. His toughness has a definite quality of fatalism and nihilism, which are the hallmarks of Film Noir. We have a word for this – “Melancholy”.
Chandler will double-down on this aspect of the detective in Marlowe, who constructs his identity through the medium of loss, indefinite sadness, discontent, and a sense that the world is arranged principally to kick men like him in the teeth. It’s a short leap from the melancholic reverie of Marlowe to the resigned determination of the genuinely disadvantaged VI Warshawski and Easy Rawlins, who more properly occupy the role of the outsider and underdog that Marlowe regards as his lot in life.
This makes the sense of melancholy a potentially far more useful tool for understanding the difference in approach between the two great schools of detective fiction, because, as noted above, they are formally often indistinguishable. All detectives question suspects, search for clues, and use “ratiocination” to identify the murderer; not all detectives suffer from melancholy. Holmes, for example, is only melancholic when not detecting, at which times he diverts himself in other vices.
 Wright, Willard Huntingdon. “Twenty Rules for Writing Detective Stories.” In The Art of the Mystery Story: A Collection of Critical Essays, edited by Howard Haycraft. New York: Biblio and Tannen, 1928.
 Moretti, Franco. “The Slaughterhouse of Literature.” MLQ: Modern Language Quarterly 61, no. 1 (March 2000): 207–27.
 DeFino, Dean. “Killing Owen Taylor: Cinema, Detective Stories, and the Past.” Journal of Narrative Theory 30, no. 3 (October 1, 2000): 313–31.
 Mooney, William. “Sex, Booze, and the Code: Four Versions of the Maltese Falcon.” Literature/Film Quarterly 39, no. 1 (2011): 54–70.