Analyses on Limitations of Information Theory

The paper analyzes the limitations from the angles of conditional entropy and the expression of information. It is pointed out Shannon's definition of information is not absolute and the probability in the expression of information maybe random variable in practice, but in information theory the probability is treated as a fixed value, then the application of Shannon's theory is limited. It is stated that people would select information that is more reliable but more uncertain than the reverse in practice. The signality of the reliability of information which is ignored in Shannon's information theory is indicated and the clew to measure the reliability of information is given to be the uncertainty of probability.