On Sense And Reference by Gottlob Frege

The work distinguishes two aspects of linguistic meaning: the sense (the mode of presentation or way an expression presents its referent) and the reference (the object or truth-value the expression stands for). It explains how different expressions can share a reference while conveying different cognitive value—accounting for why identity statements can be informative—and argues that the reference of a sentence is its truth-value while the sentence’s sense captures its cognitive content. The distinction also clarifies problems about empty or non-designating terms and about substitutivity in propositional attitude contexts, laying the foundation for a semantic theory in which sense fixes reference and secures informativeness and logical role.