How is the principle of the more difficult reading used in textual criticism?

In textual criticism, the principle of the more difficult reading—expressed by the Latin maxim difficilior lectio potior—is a rule of thumb used to help critics decide between variant readings in manuscripts.1

The principle suggests that the more difficult reading is to be preferred over an easier one. This is based on the observation that copyists were historically more likely to "correct" or simplify a text that they found confusing, obscure, or grammatically awkward. Therefore, if a manuscript contains a reading that is challenging or unusual, it is less likely to be the result of a scribe’s intentional simplification and more likely to represent the original text from which later, easier versions were derived.1

Critics use this principle alongside other criteria, such as utrum in alterum abiturum erat ("which reading would be more likely to have given rise to the other?"), to balance probabilities when evaluating the authenticity of a text. However, these are considered useful guidelines rather than absolute laws, as they ultimately reduce to the broader goal of identifying the "better" reading.1