The Truth-Conditional Theory states that the meaning of a statement is determined by the conditions under which it is true.

The Use Theory argues that the meaning of an utterance is determined by its use in a particular context or situation.

The Reference Theory proposes that the meaning of a word is determined by the object or entity to which it refers.

The Mental Representation Theory suggests that the meaning of a word or concept is determined by the mental representation or image it evokes in the mind.

Bertrand Russell is widely recognized as a key figure in the development of the Truth-Conditional Theory.

Ludwig Wittgenstein is often credited with introducing the Use Theory in his later philosophical work.

John Searle is a prominent philosopher who has defended and elaborated on the Reference Theory.

Hilary Putnam is a philosopher who has made significant contributions to the Mental Representation Theory.

The Truth-Conditional Theory emphasizes that the meaning of a statement is primarily determined by the conditions under which it is true.

The Use Theory suggests that the primary function of language is to perform actions or bring about changes in the world.

The Reference Theory proposes that the meaning of a word is determined by the object or entity to which it refers in the real world.

The Mental Representation Theory suggests that the meaning of a word or concept is determined by the mental representation or image it evokes in the mind.

Bertrand Russell is widely recognized as a key figure in the development of the Truth-Conditional Theory.

Ludwig Wittgenstein is often credited with introducing the Use Theory in his later philosophical work.

John Searle is a prominent philosopher who has defended and elaborated on the Reference Theory.