The problem of criteria and methods of historical source criticism has rarely been the subject of special study. It is most often set forth in textbooks of historical method or in general introductions to historical study. And yet a number of extremely complex and important problems are related to source criticism: principles of evidence in historical study, the relation between deduction and induction, between synthesis and analysis, and so on.
For historians of medieval Russia, as for medievalists in general, these problems are of particular significance. In this field we constantly encounter the situation when one or another fact is attested by a small number of sources, sometimes a single one. The paucity of sources, their far from complete information, and their frequent tendentiousness—all this confronts scholars with the necessity of studying them with intensity and with extreme caution.