 Finally, it is important to point out that the system we have just described, i.e., second-order logic with identity and comprehension principles, extended with \(\lambda\)-expressions and \(\lambda\)-Conversion, is consistent. Its axioms are true even in very small interpretations, e.g., ones in which the domain of objects contains a single object and each domain of \(n\)-place relations \( (n\geq1)\) has just two relations. For example, if the domain of objects contains a single object, say b, and the domain of 1-place relations contains two concepts (i.e., one which b falls under and one which nothing falls under), then all of the above axioms are true, including the Comprehension Principle for Concepts and 1-place \(\lambda\)-Conversion. Even so, the system described above requires that every concept has a negation, every pair of concepts has a conjunction, every pair of concepts has a disjunction, etc. The reader should be able to write down instances of the comprehension principle which demonstrate these claims.