Willingness to tell the truth
The process of invalidating sources is even more conspicuous when practitioners set out to ascertain whether a witness or source was willing to tell the truth.
Historians are especially tuned to witnesses who shade their testimony for personal motives, to please or displease another party, or who simply unconsciously colour their observations or thoughts with religious, social, economic, political, racial, national, regional and/or community nuances. Hence questions about motives and affiliations are mandatory in establishing the validity of a source.