Frege's Ten Organizing Principles

1. Anti-psychologism

Words are not marks or indicators of psychological states ('ideas', for Locke).

2. The Compositionality Principle

The meaning of a sentence is a function of the meanings of its parts.

3. The Context Principle

The meaning of an expression is given by the linguistic contexts into which it enters.

4. Sense and Reference

Any fully meaningful expression has two kinds of meaning: The reference of the expression and the sense of the expression which determines its reference.

5. Transparency and Objectivity of Sense

Senses are objective, real, mind-independent, and secure the capacity of language users to communicate.

6. Concept and Object

Names refer to objects, if they refer at all, while predicates refer to concepts, which Frege construes as functions mapping objects to truth values.

7. Substitutivity of Identicals

Co-referring names may be replaced one for the other, salva veritate, in any statement in which they occur.

8. Extensionality

Co-extensional predicates may be replaced one for the other, salva veritate, in any statement in which they occur.

9. Ideal Language

In a perfectly regimented language, names and predicates would be mapped one-to-one and onto objects and concepts, respectively.

10. Logicism

In an ideal mathematical language (but see his "Begriffschrift"), the truths of mathematics would be shown to be entirely reducible to truths of logic.