I would agree with the answer above that a key Enlightenment trait of Pride and Prejudice is Elizabeth's faith in thinking for herself. The Enlightenment represented a shift from relying on tradition and received authority to make decisions to questioning and using reason and experimentation to arrive at truth.
During the Enlightenment, writers such as Mary Wollstonecraft in Vindication of the Rights of Woman argued in favor of rational, companionate marriage. This was the idea that a wife should be more than a servant and child-bearer to her husband. She should, instead, be educated to be a rational companion and friend to her spouse. The two partners should esteem each other. Elizabeth very much desires this kind of marriage. She insists on marrying the man she chooses to marry. She rejects Mr. Collins's marriage proposal because she does not respect him. She knows her own mind and, like a good Enlightenment woman, says to Mr. Darcy,
There is a stubbornness about me that never can bear...
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