Lectio difficilior potior

Lectio difficilior potior (Latin for "the more difficult reading is the stronger") is a main principle of textual criticism. Where different manuscripts conflict on a particular reading, the principle suggests that the more unusual one is more likely the original. The presupposition is that scribes would more often replace odd words and hard sayings with more familiar and less controversial ones, than vice versa.^[1] Lectio difficilior potior is an internal criterion, which is independent of criteria for evaluating the manuscript in which it is found,^[2] and that it is as applicable to manuscripts of a roman courtois, a classical poet, or a Sanskrit epic as it is to a biblical text.

The principle was one among a number that became established in early 18th-century text criticism, as part of attempts by scholars of the Enlightenment to provide a neutral basis for discovering an urtext that was independent of the weight of traditional authority.