Deductive reasoning, also known as deductive method, comprises the analysis of elements that allow to achieve a positive or negative result. To put it better, reductive reasoning is basically a kind of argument in which the conclusion reached refers to the previous assumptions addressed.
The use of deductive reasoning is useful for people to make decisions based on fact rather than mind-boggling and unrealistic ideas. Deductive reasoning states that if something is right, it is because there is concrete evidence and conclusions to believe that something is right. Thus we can say that if the usefulness of deductive reasoning is to provide rational conclusions.