James Stewart did not receive an Oscar nomination for portraying Rupert Cadell in Rope.
Apparently James Stewart thought himself miscast in this film as a intellectual who does not mind telling people about his idea that murder should be acceptable by certain people. Now I will get to Stewart in a moment, but I will say who would have been perfectly cast in the part would have been James Mason. Yes this might be a bit of a conflict since Mason is mentioned by name in the film, but he would have been perfect in creating that pompous entitlement, but as well would have been articulate as well as properly sardonic when he is required to espouse about his various theories. To see Mason deal with the crisis of conscience really would have been something to see.
Well Mason was clearly not cast and Stewart was given the part which is quite a change from his previous roles. He usually played the passionate man fighting against something or the ah shucks romantic. The end of Its A Wonderful Life suggested a darker side to Stewart though which was something that he tapped into for much of the rest of his career after World War II. Stewart perhaps was miscast though as he is definitely not someone you think of as a this type of teacher with some delusions of grandeur. Of course it is a testament to Stewart as an actor that he does try to compensate for the fact that he really does not fit the part all that well particularly early on.
Cadell at first is very much the intellectual who does not mind flaunting his intelligence purely for fun. Stewart actually does something very well here which he dials back on his usual vocal manner. He takes away the warmer qualities of his voice that make you feel welcome instead having a much colder style here that is fitting for Cadell. Stewart is not exactly how you might picture the pompous type but he is still able to get across the nature of Cadell nevertheless, in fact Stewart's natural likability probably helps with his characterization. Cadell quietly makes fun of people but no one really takes offense and Stewart makes this work through his style of smugness.
Stewart is actually rather subtle about Cadell's sense of superiority. He makes there is his sometimes aloof manner and sometimes sarcastic delivery, but he never is overt about it. He kind of eases into it even when he describes his ideas about murder it just something he can talk about calm and coolly. This is not how I would exactly envision this type of man, but Stewart's approach actually does work getting across the nature of the character quite effectively. In fact Stewart's style shows a bit of a lack of thought in what Cadell says. This is not to say he has not thought out what he says well, but Stewart has it is something he has really thought the full implications of what he says.
Cadell role outside of being an inspiration of sorts for the two murderers is being the man who figures out what they have done. Stewart is excellent in portraying this aspect and does well to show Cadell slowly figuring out the scheme. His reactions are terrific throughout as he conveys the thought process in Cadell which is slowly pulling back the layers of the plan. Stewart is particularly strong when he interrogates the men in the way he seems still seems somewhat dispassionate but there is that incisive undercurrent as he keeps questioning them and seeing that there is clearly something that they are both hiding.
This leads to the point where Cadell finds out what they did and the last thing he feels is pride from his accomplishment. Instead Cadell has to face the shame of someone finally murdering based on his ideas of superiority. Stewart is a master of the passionate speech denouncing an evil and his speech in this film is no exception. He has a tremendous force about it and is perfect to finally slap the smug look off of the mastermind of the two killers. Stewart adds a little more though as Cadell's disgust is not only for what the killers have done but also due to his own guilt from his past words. Stewart makes the moment very powerful because he get across the hate Cadell feels for their actions in his words, but as well the shame he feels in his face.
This is a strong performance from Jimmy Stewart and it is a great example of an actor still performing well despite the role not being right for him. I would say that James Mason would have been much more fitting for the part, and if he had been the one with the role he very well could have been all time great. Stewart does not fit the role of the smug professor by any means Stewart just by his nature does not come off as that sort of guy. To his credit though Stewart tries his best to overcome the fact that he was miscast in the role. He still succeeds in the part by adapting it best he can to his on screen persona. It is not an absolutely perfect characterization because the right casting is necessary, but nevertheless Stewart still gives an impressive performance.