Abstract: Atom propositions are the basic unit of symbolic logic. The relationship between atom propositions' relativity and logic calculation was analyzed. In classical two-valued logic, the truth value of the proposition logic calculation result only bears on the truth value of the proposition which participates in the logic calculation, but is independent of the idiographic content in the proposition. In probabilistic logic, proposition logic calculation is decided by the relationship of propositions. The different propositions with the same truth value can not have the same logic calculation result. Implication connectives which are compatible with classical two-valued logic were defined, and they overcome the shortcoming that conditional probability can not be used to inference.