An immediate inference is an inference which can be made from only one or proposition. For instance, from the statement "All toads are green." we can make the immediate inference that "No toads are not green." There are a number of immediate inferences which can validly be made using logical operations, the result of which is a logically equivalent statement form to the given statement. There are also invalid immediate inferences which are syllogistic fallacies.
Cases of the incorrect application of the contrary, subcontrary and subalternation relations are syllogistic fallacies called illicit contrary, illicit subcontrary, and illicit subalternation. Cases of incorrect application of the contradictory relation are so infrequent, that an "illicit contradictory" fallacy is usually not recognized.