 In answering this question, one has to take into account that any valid inference should be based on logical rules which, according to a commonly accepted view, should at least guarantee that in a valid inference the conclusion(s) is (are) true if all the premises are true. Translating this demand into the Fregean terminology, it would mean that in the course of a correct inference the possession of the truth value The True should be preserved from the premises to the conclusion(s). Thus, granting the realistic treatment of truth values adopted by Frege, the understanding of logic as the science of truth values in fact provides logical rules with an ontological justification placing the roots of logic in a certain kind of ideal entities (see Shramko 2014).