Realism; Historical Fiction
Time for a word problem: if a book published in 1859 describes events that take place between 1799 and 1807, does that make it historical fiction? The possible answers are 1) Ten pencils and seven pens; 2) Carbon dioxide; 3) Enough baseballs to fill the bathtub halfway to the brim; and 4) Yes.
Unless something is wrong with you, you probably realize that #4 is the correct answer. Adam Bede is a work of historical fiction, no question. What else do you call a book where the characters read fresh-off-the-press copies of Lyrical Ballads and complain about Napoleon?
But Adam Bede isn't a fancy costume drama. Instead, Eliot aspires to give us a picture of the way that everyday people were. The whole novel pursues a "rare, precious quality of truthfulness"—a sense of how people really think, how emotions really operate (17.5).
Eliot's "historical" characters don't swing swords and ride horses. They swing complex intellectual constructs and ride deep personal crises. Okay, so the comparison doesn't quite work. But the whole "historical and psychological realism" thing: that works like a charm.