The paper discusses the meta-philosophy of thought-experiments, in particular its neglected diachronic aspect, focusing on Putnam’s work as the paradigm case, and on the trail that developed out of the Twin Earth thought-experiment. Putnam's experiment is discussed from a perspective that combines metaphilosophy and actual history of analytic philosophy. Peter Unger has branded the whole debate around it as empty and fruitless. A meta- philosophical analysis shows him to be wrong. The experiment as originally proposed already appeals to a broad (...) variation of examples and intuitive induction; the variation continues in other works addressing the issue, and produces interesting results. The second aspect is the search for reflective equilibrium, lasting till the present day. The internal logic of these processes is discussed, in order to show that the accusation for emptiness turns against Unger himself. In general, debates around thought-experiments, the already famous and also around new ones, make a large part of contemporary analytic philosophy. The way to understand a large part of this, and of debates surrounding it, is to link it to the internal understanding of a typical thought-experiment; stages of a particular experiment get discussed, developed and changed in the history of a particular trail produced by it. This is an important way in which a philosophical tradition is born, and we need to combine synchronic and diachronic approaches in order to understand it. (shrink)

In this dissertation on Hilary Putnam's philosophy, I investigate his development regarding meaning and necessity, in particular mathematical necessity. Putnam has been a leading American philosopher since the end of the 1950s, becoming famous in the 1960s within the school of analytic philosophy, associated in particular with the philosophy of science and the philosophy of language. Under the influence of W.V. Quine, Putnam challenged the logical positivism/empiricism that had become strong in America after World War II, with influential exponents such (...) as Rudolf Carnap and Hans Reichenbach. Putnam agreed with Quine that there are no absolute a priori truths. In particular, he was critical of the notion of truth by convention. Instead he developed a notion of relative a priori truth, that is, a notion of necessary truth with respect to a body of knowledge, or a conceptual scheme. Putnam's position on necessity has developed over the years and has always been connected to his important contributions to the philosophy of meaning. I study Hilary Putnam's development through an early phase of scientific realism, a middle phase of internal realism, and his later position of a natural or commonsense realism. I challenge some of Putnam’s ideas on mathematical necessity, although I have largely defended his views against some other contemporary major philosophers; for instance, I defend his conceptual relativism, his conceptual pluralism, as well as his analysis of the realism/anti-realism debate. (shrink)