"Luck" as opposed to "entitlement" accounting for one's lot in life
The importance of luck in Lucky Jim is signaled first by the title, and then by the repetition of the concept throughout the text. The novel charts both the bad and good luck of Jim Dixon, but Jim's feelings towards luck become more elaborate as the story proceeds. Dixon's bad luck provides some of the humor of the novel, but when he stops to rue his misfortune, the passages set aside humor for self-pity. At other points in the story, however, such as the incident with Mrs. Welch's sheets, bad luck is used to downplay Dixon's role in his own downfall. Once Dixon learns to trust luck, things turn around for him, and he begins to have a say in his fate.
Dixon's take on luck, is in direct contrast to the philosophy of a character like Bertrand Welch, who does not see discrepancies in class in terms of luck, but rather as the way things should be. Thus, while Dixon considers himself lucky when Christine agrees to come home with him, Bertrand considers Christine to be his "right." Although Dixon's passive surrender to "bad luck" can be pathetic, it is also indicative of his concern for others, while Bertrand's sense of entitlement reveals his self-centeredness.
The value of straightforwardness over pretension and hypocrisy
The main traits for which characters in Lucky Jim are satirized are hypocrisy and pretension. The Welches are mocked for their social pretensions, Margaret for her melodramatic romantic, and Bertrand for his attempts to act the part of an artist. No one explains to Dixon what it is that they really want from him and they usually have ulterior motives. However, Dixon himself is slightly hypocritical when the novel begins, keeping his real emotions from those around him, and faking feelings for Margaret that he does not actually possess. It is not until the end of the novel that Dixon is able to be straightforward himself, although he learns early on to appreciate this trait in others.
The differences between social classes
The theme of the differences between social classes works on a minute level throughout the text, and Dixon, with his eye for social, visual, and linguistic nuances, is often tracing out the divisions between classes. Although these distinctions are supposed to separate the members of the lower, middle and upper class, in Lucky Jim they actually serve to separate the characters into those who attempt to have class and those who genuinely possess refinement. The Welches, with their upwardly mobile social pretension, drag out all the markings of class, such as coffee and cakes for supper, an aesthetic appreciation of amateur art, and useless clothing, but never really possess it. Meanwhile, the characters who are less mindful of social class—usually those from the lower-most class and upper-most classes—display some coarseness and flaws, but are far more admirable and refined that their pretentious counterparts.