Why are rules such as preferring the difficult reading only guidelines rather than absolute laws?

In the field of textual criticism, rules such as difficilior lectio potior ("the more difficult reading is to be preferred") are considered useful guidelines or rules of thumb rather than absolute laws because they are secondary to the primary principle that each textual case is unique.12

These principles are not rigid because they often reduce to the truism melior lectio potior ("the better reading is to be preferred"), which requires the critic to exercise judgment rather than follow a mechanical formula. Relying on absolute laws can lead to "grotesque" results, as seen when critics rigidly applied stemmatic methods to unsuitable texts.13

Ultimately, the critic’s role is to discriminate based on common sense and the specific historical circumstances of the text's transmission. Because texts have been transmitted through a unique and unpredictable combination of purpose and accident, no statistical model or schematic rule can replace the critic's need to evaluate variants on their intrinsic merits. Consequently, the best critics reject the rigid application of any method if the results conflict with reason, acknowledging that many solutions remain provisional.1243