Neo-Bayesianism, the statistical methodology based on the idea of probability interpreted as degree of belief, formulates inductive inferences in terms of probability theory, and justifies them under assumptions of rationality. Conditional probability with condition of zero probability is among those inductive inferences formulated within the Neo-Bayesian terminology. This paper aims to call attention to the need for the justification of the zero conditional probability by pointing out that so far no theorem has justified it successfully.