不确定性（Uncertainty）是现实经济生活中的一种常态，包括税收理论在内的经济学理论只有将不确定性做为一种重要前提或制约条件，才能对经济生活作出现实的描述与正确的指导。长期以来，在传统经济学的基本假设之一——确定性前提之下，税收理论体系已得到长足的发展。七十年 Uncertainty is a normal state in real economic life. Economic theory including tax theory can make a realistic description and correctness of economic life only by using uncertainty as an important premise or constraint Guidance. For a long time, under the premise of certainty, one of the basic assumptions of traditional economics, the tax theory system has been greatly developed. Seventy years