Non-formal Logic A Number Of Issues

As a branch of a logic, informal logic appeared in Europe and America during the 1960s—1970s . It is focus on the analysis, evaluating and construction of ordinary argument in daily life, which make up for the shortage of logic science that doesn't pay close attention to daily life. Informal logic is a lively science which give the new orientation to logic science .There are two portion in this paper : chapter one is the first portion, which introduce the background, researching situation and theory source of informal logic; the last portion including 2,3,4 chapter, is the key potion of the paper ,which focus on the argument evaluation of informal logic.During the course of argument studying , it is found that validity (exactly, deductive validity) is the standard of argument evaluation informal logic. However, the standard finds itself in a difficult position when it is used for ordinary argument. Chapter two concerns itself with the inadaptability of deductive validity as the highest criterion in argument evaluation, and introduce that some people have restricted or revised the concept of validity to keep it as the core of argument evaluation . It is argued that they are all in vain.In chapter three it puts forward introduction and comments on some influential theories of argument evaluation . They are the Field Theory , ARG theory , TARG theory . By studying on these theories, analyzing their advantages and disadvantages, we know what to do with our own research.Chapter four is the heaviest part in this paper. It carries out some important discussions about the criteria of argument evaluation ,which including the criteria of Acceptability, Relevance and Good ground. Some important conclusions are : Truth requirement should be include in Acceptability requirement ; Relevance is the most basic but most difficult element to define in the theory of argument evaluation, by now we haven't had a appropriate definition ;Contextual explanation of relevance is helpful to understand the essence of relevance; Counter-considerations are the key to evaluate the sufficiency of argument. Besides, the chapter also carries out other discussions about the sufficiency criteria of plausible argument.