Putnam employed his causal theory of reference to address ‘the paradox of meaning variance’ that resulted from a combination of insights by Frege and the later Wittgenstein. How did that paradox arise and how successful, do you think, was Putnam’s attempt to overcome it?
Frege’s main work in question, On Sense and Reference (Über Sinn und Bedeutung, 1892) is concerned with the question of how the sense of a sign is related to the meaning which is expressed by the sign. Frege examines the question of how the object which is designated by a sign is related to the meaning which is expressed by the sign, explaining that changes in the sense of a sign may change the meaning of the sign, and he describes how changes in the sense of a sign may also change the sense of the expression that contains the sign. The relation between sense and reference is drawn, and the relationship between signification and meaning is examined.
In his early work the Tractatus , Wittgenstein attempted to acquire an understanding of how language works. He argued that in order to be able to approach philosophical enquiry, we must first understand our use of language, and how it relates to the world we observe. The main claim in this work seems to be that thoughts are pictures of how things are in the world. One cannot talk of things that fall outside reality without engaging in meaningless discourse, as there is nothing for such thoughts to picture. Sense relates to propositions only in that propositions picture existing facts about the world, and the very definition of reality is the sum total of facts about the world.
In his later writings, especially Philosophical Inquiries, Wittgenstein refutes many of these earlier views and he argues then that the function of language was not to mirror reality after all. According to this later Wittgenstein, the meaning of words is not be found by ascerting their connection with particular objects. Instead, the meaning of...