From a computational perspective, logics give us an important tool for performing inference. Suppose you state that Freedonia is not to the north of Sylvania, and you give as your reasons that Sylvania is to the north of Freedonia. In this case, you have produced an argument . The sentence Sylvania is to the north of Freedonia is the assumption of the argument while Freedonia is not to the north of Sylvania is the conclusion . The step of moving from one or more assumptions to a conclusion is called inference . Informally, it is common to write arguments in a format where the conclusion is preceded by therefore .