The last stage of the judicial process is the formation of an argument of the syllogism of formal logic consisting of premise and conclusion. In this process, syllogism from the point of view of logic is a statement composed of propositions, which, if assumed to be definite and certain, inherently another theorem emerges from it. The use of syllogism of formal logic as the main method of reasoning in judicial ruling process has always been followed by many criticisms, the most important of which is the refusal to fulfill the description of the certainty of the premises and, consequently, the failure to issue inviolable conclusions because of the interference of human factors with emotions and emotions, and also, the impossibility of discovering the certain facts of the case, which are in conflict with the known features of this type of argument. But these objections in general must be answered as follows: First, what is to be expected from the certain preconditions for the formation of a reasoning argument in jurisprudence is the acquired knowledge which is considered acceptable and sufficient in convincing the judge; Not logical or philosophical certainty. Secondly, deduction in its fourteen sources can be divided into two practical applications of argument and controversy. In argument, the substance of "Conjectures" comes from certainty and will be used in the minor premise as the source of the judge's legal syllogism. And in the controversy (debate), he introduces the material of "Famous subjects and Certainties" with special and significant conditions, as the basis of the judge's knowledge, which provides the means to eliminate the said objections in appropriate ways.