 The primary reasons of error may be abstracted from a strong characterization of a syllogism. If a syllogistic argument is (a) arranged according to one of the figures and its mood is productive, (b) it has primary distinct parts (terms) and secondary distinct parts (premises), (c) its premises are true, (d) distinct from and (e) better known than the conclusion, then a true conclusion must follow. Otherwise, at least one of conditions (a)–(e) has not been met.