The film There Will Be Blood is based upon this 1927 Upton Sinclair novel. It is in fact based very loosely, as these two stories are nearly as different as night and day. Not that there is anything intrinsically wrong with this, since films and novels are very different forms of expression. It's perfectly legitimate to take the kernel of one story and turn it into something completely different. Still, it's interesting to look into the differences, and speculate on why the filmmaker made the changes he did.
The film is the story of an evil man, lacking in humanity and motivated by greed. His name is Daniel Plainview; he has an adopted son, whom he uses as a kind of prop, a cute accessory when dealing with people in order to foster the illusion that he's a decent fellow. In Upton Sinclair's book, the character is named J.A. Ross (the name Plainview appears only once in the book, as an alias Ross uses in a telegram) and he is very fond of his boy. The novel is in fact written from the son's perspective, and it is the relationship between J.A. Ross and J.A. Ross Jr., (nicknamed "Bunny") that is the heart of the novel. There is a great deal of love in the relationship, tempered by an amicable difference of opinion, and ultimately rendered tragic by a fundamental difference in temperament.
Bunny is "soft". His sympathies lie with the oil workers and their families, the poor landowners who are fooled into selling their lots to sharp developers, and with the small-time operators who inevitably fall by the wayside in the struggle with the big ones. Dad is a hard-headed business man, a successful oil operator who understands that deals must be made and palms greased in order to get the oil out of the ground. A man would be a fool to show his hand when he suspects there is oil under a rancher's property. If he doesn't grab up the pipe and timber he needs for wells straight away, his competitors will do so, and will freeze him out, so he offers the pipe or lumber dealer a percentage, off the books, to sweeten the deal. Ross can't wait around for the county to pave a road to his site; time is money, so he puts some of that money into the hands of the appropriate official, in order to get the job done. After all, the official earns but a pittance with his county salary, so think of it not as a bribe but as fair compensation for all the extra time and work he will have to put in. Dad is only doing what all the other oil men do, and he is by their standard unusually honest: he keeps his word and he's careful not to tell an outright lie.
Bunny however is troubled by all this. As much as he loves his dad, he can't help but see these things as cheating, kickbacks, and bribery. He wonders at his father's motivations, which truly have nothing to do with greed; J.A. Ross Sr. cares little about money other than as something they'll need to get the next oil field into production. He is committed to the job at hand, which is to get oil out of the ground. America needs oil, that is reason enough for him. The father in turn wonders at this odd son of his, who can't help but look into things, and trouble himself over things that can't be changed. He keeps hoping his son will outgrow it, and keeps on loving him when he doesn't.
They love each other right till the end, when Dad dies in European exile, chased out of his native California by threatened prosecution and Congressional inquiry, events that are clearly based on the actual Teapot Dome oil scandal. Besides his father, the other great attachment of Bunny's life is with his friend Paul Watkins, a labor activist, a Leftist so radicalized that he sympathizes with the Bolshevik revolution in Russia. Bunny is thus torn, trying to bridge a hopeless division between his intellectual and personal life. He is a millionaire's son who believes deeply in the cause of Socialism.
This, then, is the crucial difference between the book and the movie. The movie is a tale of an evil man, a purely personal evil; if there is any cause whatsoever of this evil, it lies in his sinfulness, the sins of greed and ambition. The book on the other hand is a tale of the inevitable conflict between capital and labor, a social rather than a personal issue. There is evil present in Upton Sinclair's novel, but it isn't the oil-man's evil; to quote the final line of the book, there is
"...an evil Power which roams the earth, crippling the bodies of men and women, and luring the nations to destruction by visions of unearned wealth, and the opportunity to enslave and exploit labor."
Evil is, in short, the Capitalist system! Upton Sinclair was of course a Progressive reformer, a socialist, and-- intellectually at least-- a Marxist. I suspect Paul Thomas Anderson wasn't about to touch any of this with a ten foot pole. Much of it would seem archaic: early twentieth-century stuff of purely historical interest. (I myself found it of great historical interest... but then maybe I'm just weird!) I can't help but wonder, though, if it's quite right to take an author's work and turn it so completely on its head.
Curiously, this is a turn of events that is anticipated within the novel itself, which treats of the film industry by way of Bunny's romance with a screen star named Vee Tracy. Bunny learns from close up the film business's propensity for taking socio-economic themes and turning them into the purely individual, in effect defusing them. Bunny is horrified to learn that Vee's movie, set during the Russian Revolution, centers on a love story between a beautiful noblewoman and a dashing American secret agent. I can only wonder what Sinclair would think about seeing his call for collective action transformed on the screen into a tale of individual morality.
Anything so Left-radical as Oil! is surely unmarketable these days. "Capitalists" are now called "entrepreneurs", benevolent beings virtually above criticism. It's an interesting historical-cultural drift. In his day, Upton Sinclair was a popular author, and the Progressive agenda had a widespread appeal.
Oil! is a polemical work, with a clear agenda. It is schematic at times, and a bit strident. It might be called dated, but on the other hand it is perhaps invaluable for offering a glimpse into the mindsets and opinions of what was a very different era, though an era less than a century past.