Abstract: Critical thinking researches into inferences and arguments like the previous theories of logic,but it doesn't carry forward,continue and develop the original tradition of logic.It brings about a profound revolution in the concept of logic.It realizes the major transitions shifting from form to content,reducing the valid to the reasonable,going from certainty to uncertainty,and going from study to society.It opens up a new field for the research on inferences and arguments,and provides a tool which is generally applicable for the analysis and evaluation of inferences and arguments,and can help people with more reasonable inferences and arguments.