In February 2017, the logical community suffered an irreparable loss of two remarkable logicians – Alexander Karpenko and Elena Smirnova. In this issue E. D. Smirnova's work on the problems the foundations of logic, the nature of apodictical knowledge and the delineation of ideal entities and relationships that are the basis of logical systems.

This issue also features a number of works on non-classical logic, as well as the history of ancient and medieval logic.