An **immediate inference** is an inference which can be made from only one statement or proposition.^{[1]} 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.

## Valid immediate inferences

### Converse

- Given a type
**E**statement, from the traditional square of opposition, "No*S*are*P*.", one can make the*immediate inference*that "No*P*are*S*" which is the converse of the given statement. - Given a type
**I**statement, "Some*S*are*P*.", one can make the*immediate inference*that "Some*P*are*S*" which is the converse of the given statement.

### Obverse

- Given a type
**A**statement, "All*S*are*P*.", one can make the*immediate inference*that "No*S*are*non-P*" which is the obverse of the given statement. - Given a type
**E**statement, "No*S*are*P*.", one can make the*immediate inference*that "All*S*are*non-P*" which is the obverse of the given statement. - Given a type
**I**statement, "Some*S*are*P*.", one can make the*immediate inference*that "Some*S*are not*non-P*" which is the obverse of the given statement. - Given a type
**O**statement, "Some*S*are not*P*.", one can make the*immediate inference*that "Some*S*are*non-P*" which is the obverse of the given statement.

### Contrapositive

- Given a type
**A**statement, "All*S*are*P*.", one can make the*immediate inference*that "All*non-P*are*non-S*" which is the contrapositive of the given statement. - Given a type
**O**statement, "Some*S*are not*P*.", one can make the*immediate inference*that "Some*non-P*are not*non-S*" which is the contrapositive of the given statement.

## Invalid immediate inferences

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.

### Illicit contrary

- It is false that all
*A*are*B*, therefore no*A*are*B*. - It is false that no
*A*are*B*, therefore all*A*are*B*.

### Illicit subcontrary

- Some
*A*are*B*, therefore it is false that some*A*are not*B*. - Some
*A*are not*B*, therefore some*A*are*B*.

### Illicit subalternation (Superalternation)

- Some
*A*are not*B*, therefore no*A*are*B*. - It is false that all
*A*are*B*, therefore it is false that some*A*are*B*.

## See also

## References

**^**Churchill, Robert Paul (1990).*Logic: An Introduction*(2nd ed.). New York: St. Martin's Press. p. 162. ISBN 0-312-02353-7. OCLC 21216829.Immediate inference is the assumption, without intervening—or 'mediating'—premises, that because one categorical statement is true (or false), a logically equivalent categorical statement must also be true (or false).