On Bolzano's Logic Thoughts

Heinrich Scholz said in his book "Concise History of Logic","the explanation of this type of interpretation(referring to the formal interpretation of classical logic)was first made by two great German logicians of the 19th Century,Bolzano and Frege." The importance and influence of Frege is widely recognized and accepted since the rise of analytical philosophy.Yet Bolzano,whom Scholz thought can be placed in a similar position to Frege in the history of logic,has been ignored.Many people know Bolzano through the famous phenomenologist Edmund Husserl,who claimed that his notion of priori and intentionality benefited a lot from Bolzano;or through Bolzano-Weierstrass theorem in the area of mathematics.Bolzano's philosophy stems from Kant,and therefore is overall subordinated to the general phenomenological tradition.But some essential aspects of his thoughts foresee the connection between logic and grammar,which is beyond the general phenomenological tradition.In the Chinese context,there is little research on Bolzano's logic thought.Several reasons might explain this situation.First,it is probably because his logic thoughts were scattered in many fragments of his articles,letters and unpublished anonymous work,these works are hard to collect and lack of coherence.Second,it is difficult to reconcile between modern logic and German philosophical tradition,and the development of mathematical logic is in a way increasingly deviating away from the development that Frege originally envisaged.And the logicians lived between Leibniz and Frege are fallen into the shade within the growing reputation of Frege.Third,the learning of modern logic focuses mainly on the logical inference and its applications,however,the study of the history of logic is somewhat neglected.Fortunately,Bolzano has gained more and more attention in the context of German and English currently.This change offers a lot of facilities for exploring his logic.This article discusses the origin of Bolzano's logic above all,and then elaborates his theory of proposition,theory of truth and theory of deducibility.The theory of truth is more crucial and original among them.At last,there is an endeavor to integrate Bolzano's theory of truth with Tarski's convention-T to form a BT-scheme and explore it under the discussion of modern logic.