What do you think the differences are between Marlowe and Spade? For that matter, the differences between them and the Continental Op?
I have my theories, but I’d like to hear yours.
Let's see for Spade/Marlowe! I sadly cannot answer for the Continental Op, since I haven’t read that yet.
They’re both ideals, but in completely different ways.
Hammet made up a perfect detective in a realistic, dirty world according to his IRL experience. Sam Spade has good instincts, always knows what to do and ask, plays people like fiddles, wins fights, dominates the scene whatever happens, he’s even got a little bit of a conscience if you squint. Spade is so good he overcomes any treachery or trap. In fact, he is so good he solves a case that never really existed. The worst he got is being drugged, and that only slows him a little. You cannot stop this man, and you can’t prevent him from winning.
=>Tl;dr: in a dirty realistic world, Sam Spade eats the world alive and gets out unscathed. He wins because he’s an ideal.
Marlowe is an ideal of incorruptibility. He refuses more money than he can afford. He accepts cases only if he thinks he can make a difference. He has a soft spot for helpless people and dignity. If he has to choose between his standards and his life or happiness, he will choose the former any time. He wants to be the perfect chivalrous knight, ready to lay down his life for the pure damsel/good king/pretty prince. Only none of these exist - they’re all people, more or less flawed, and this way of thinking leaves him wide open to incredible physical and emotional hurt. It leaves him miserable, poor, forever alone. He knows this and still sticks to his guns, no matter what.
=>Tl;dr: in a dirty realistic world, Philip Marlowe stays unstained no matter how much he gets chewed up. He can’t win because he’s an ideal.
They’re both not quite human, but in wildly different ways.
As said above, Space is inhumane because he’s a paragon of efficiency. Though the reader follows his point of view, at no moment we know for sure what he knows and what he thinks. He stays a total mystery – of course, this is also because we have only a short novel (and a short story, I think?) about him. Emotions seem to bounce back on him.
You could argue that Marlowe gets more and more ghost/shadow attributes, trapped between this rotten world and his Knight complex, clinging to a very obsolete ideal that never existed, knowing everyone’s secrets but leaving/left by everyone aside, not living for himself but refusing to die.
The narrations are polar opposites.
Hammet’s cold, simple, nearly mechanic third person prose where Spade acts and does things with very little explanation vs Chandler’s poetic and flowing monologues about how Marlowe hates this interior design or thinks the bug in a police office is pretty cute. Crucial parts of their thought process are hidden, you don’t know much about their past, but that makes Marlowe a much warmer, approachable character. Spade stays an enigma.
They’re both very good, but!
Spade’s efficiency has a price. If himself is unscathed, everyone else around him is touched: his partner dies, the women he loves/sleeps with get hurt. By the end, the police holds a grudge more than ever and the only person who sticks with him is his adorable secretary. His job was basically breaking a dream. As far as we know – granted, it isn’t much - his world is empty and has just become emptier.
Marlowe is basically a death omen, poor guy. If he’s on the case, get ready for a load of corpses to show up. If he’s a good detective, he can’t help if people make horrible choices or get killed when his back is turned. If he’s a good fighter, he can’t help if he’s outnumbered or overpowered. That forces him to get messy and do pretty “uncool” stuff: he’s so out of fuck to give by the end of Farewell my Lovely he welcomes the murderer(s) in his pajamas and tries to stop bullets with throwing pillows - that’s my favorite example, but the list goes on.
Rapport with drink is different.
When Spade drinks, he gets complimented because he does it like a man. Marlowe is written by a guy who had a drinking problem and it shows. He needs the stuff to bear what he endures, the only time he’s shown as ecstatic is the one he’s completely drunk, and he’s criticized several times about it (though Chandler, for the record, didn’t think his character was an alcoholic).
Rapport with police is different.
Oh it’s bad, but it’s bad in a different way.
Hammet shows police as inefficient, corrupted, or just plain stupid. They serve as antagonists – well, vague annoyances all along. Hammet screams ACAB all the way. If police is actively after Spade, Spade brushes it off.
Police in Marlowe’s books gets a more nuanced portrait. You have the good ones who have their hands tied and can’t do much but watch the bad ones act/get fired; the efficient ones who do their jobs but are unscrupulous and ready to hurt people for it; the incompetent ones who sit on their asses all day and nothing is ever their fault; and you have the sadistic ones who hurt, kill or murder those that fall into their hands just because they can. Add to that the ambient corruption and it’s clear that the bad ones have the power – however, the less bad ones can help, sometimes. Unlikely, fragile alliances can be built. However, police is much more powerful than one random man and Marlowe gets arrested, beaten and kidnapped by them several times - far from being annoying puppets, they're actively dangerous when they want to be.
That's not exhaustive of course, but that covers some important points.
(That’s basically why Bogart nailed Spade but completely missed Marlowe)