In the introduction to his famous book, La Science et l’hypothèse, Poincaré remarks on the necessary role and legitimacy of hypotheses. He establishes a triple classification of hypotheses, dividing them into verifiable, useful, and apparent. However, in chapter 9, entitled ‘Les hypothèses en physique’, he gives a slightly different triadic classification: natural hypotheses, indifferent hypotheses, and real generalizations. The origin of this second classification is a lecture given at the International Congress of Physics, Paris, 1900. What are the similarities and (...) differences between these two classifications? My main purpose is to provide a possible equivalence between the two classifications in order to clarify the role of hypotheses in Poincaré’s epistemology of natural science. The discussion will be based on the two fundamental texts mentioned above and on the contrast between Poincaré’s use of the notion of hypothesis and that of some of his contemporaries. (shrink)

This paper offers an interpretation of Poincaré's conventionalism, distinguishing it from the Duhem–Quine thesis, on the one hand, and, on the other, from the logical positivist understanding of conventionalism as a general account of necessary truth. It also confronts Poincaré's conventionalism with some counter-arguments that have been influential: Einstein's (general) relativistic argument, and the linguistic rejoinders of Quine and Davidson. In the first section, the distinct roles played by the inter-translatability of different geometries, the inaccessibility of space to direct observation, (...) and general holistic considerations are identified. Together, they form a constructive argument for conventionalism that underscores the impact of fact on convention. The second section traces Poincaré's influence on the general theory of relativity and Einstein's ensuing ambivalence toward Poincaré. Lastly, it is argued that neither Quine nor Davidson has met the conventionalist challenge. (shrink)

This paper concerns the epistemic status of "Hume's principle"--the assertion that for any concepts and , the number of s is the same as the number of s just in case the s and the s are in one-one correspondence. I oppose the view that Hume's principle is a stipulation governing the introduction of a new concept with the thesis that it represents the correct analysis of a concept in use. Frege's derivation of the basic laws of arithmetic from Hume's (...) principle shows our pure arithmetical knowledge to arise out of the most common everyday applications we make of the numbers. The analysis of arithmetical knowledge in terms of Hume's principle ties our conception of number to the interconnections of which our concepts of divided reference are capable; in so doing, it locates the origin of our conception of number in the structure of our conceptual framework. (shrink)

Are there any bona fide boundaries, i.e., boundaries that carve at the joints? Or is any boundary —hence any object—the result of a fiat articulation reflecting our cognitive biases and our so-cial practices and conventions? Does the choice between these two options amount to a choice between realism and wholesome relativism?

Poincare’s arguments for his thesis of the conventionality of metric depend on a relationalist program for dynamics, not on any general philosophical interpretation of science. I will sketch Poincare’s development of the relationalist program and show that his arguments for the conventionality of metric do not depend on any global strategies such as a general empiricism or Duhemian underdetermination arguments. Poincare’s theory of space, while empirically false, is more philosophically sophisticated than his critics have claimed.

This article considers Henri Poincaré’s conventionalism in historical context by comparing his use of such terms as “convention” and “conventional” with Charles Renouvier’s. As Renouvier was very influential in late nineteenth-century France, this comparison can provide some insight into how the terms were understood at the time. Renouvier was a political philosopher as well as a philosopher of science. He drew an analogy between the conventions or social contracts that govern society at large and the conventions that governed communities of (...) researchers in mathematics and the sciences. Both kinds of conventions were living contracts for Renouvier, subject to revision and change. What emerges from the comparison is an interpretation of Poincaré’s conventionalism that belies the view that it is a rigid, unbending philosophy holding back scientific progress. Rather, it is one according to which scientists come together to form a temporary consensus about particular starting points in order to make research into nature possible yet retain the liberty to try something new when the old set of assumptions no longer proves fruitful. (shrink)

Rational Mechanics in the Eighteenth Century. On Structural Developments of a Mathematical Science. The role of mathematics in eighteenth‐century science and of eighteenth‐century philosophy of science can hardly be overestimated. However, philosophy of science frequently described and analysed this role in an anachronistic manner by projecting modern points of view about (formal) mathematics and (empirical) science to the past: From today's point of view one might be tempted to say that philosophers and scientists in the seventeenth and even more in (...) the eighteenth century became aware of the importance of mathematics as a means of ‘representing’ physical phenomena or as an ‘instrument’ of deductive explanation and prediction. But such modernisms are missing the central point, i.e. the ‘mathematical nature of nature’ according to mechanical philosophy. Moreover, the understanding of this mathematical nature changed dramatically in the course of the eighteenth century for various (i.e. mathematical, philosophical and other) reasons – a fact hardly appreciated by former philosophical analysis. Philosophy of science today should offer a more accurate analysis to history of science without giving up its task – not always appreciated by historians – to uncover the basic concepts and methods which seem relevant for the understanding of science in question. This paper gives a ‘structural account’ on the development of rational mechanics from Newton to Lagrange that tries to give justice to the fact that rational mechanics in the eighteenth century was primarily understood as a mathematical science and that – starting from this understanding – also tries to give good reasons for the fundamental change of the concept of science that took place during this period. (shrink)

Johannes von Kries’s Spielraum-theory is regarded as one of the most important philosophical contributions of the nineteenth century to an objective interpretation of probability. This paper aims at a critical and contextual analysis of von Kries’s approach: It is contextual insofar as it reconstructs the Spielraum-theory in the historical setting that formed his scientific and philosophical outlook. It is critical insofar as it unfolds systematic tensions and inconsistencies which are rooted in this context, especially in the grave change of mechanism (...) which took place in the late nineteenth century. In this regard, the paper focuses on von Kries’s understanding of natural laws and nomological knowledge in relation to his concept of objective probability. While the formal approach of the Spielraum-theory—as far as developed by von Kries—seems sound, his epistemological claims with respect to nomological knowledge sustain classical mechanism and are hence difficult to substantiate from the point of view of modern science. (shrink)

In the history of mathematics and natural philosophy Jacobi's contribution to theoretical mechanics is known as a part of the higher calculus in the tradition of Lagrange: accepted as mathematically important, it was denied to have any substantial physical or philosophical relevance. His last lectures on analytical mechanics, given in 1847–1848, three years before his death, and not yet published, show this view to be no longer tenable. These lectures are the most detailed and genuine source on Jacobi's views concerning (...) the foundations of mechanics. In particular, his criticism of the principles of mechanics is unprecedented for its time and anticipates some of Poincaré's views, published about fifty years later. The prehistory of Jacobi's Analytical Mechanics, a description of its content in general and an outline of his criticism, are presented in this paper. (shrink)

Poincaré is well known for his conventionalism and structuralism. However, the relationship between these two theses and their place in Poincaré׳s epistemology of science remain puzzling. In this paper I show the scope of Poincaré׳s conventionalism and its position in Poincaré׳s hierarchical approach to scientific theories. I argue that for Poincaré scientific knowledge is relational and made possible by synthetic a priori, empirical and conventional elements, which, however, are not chosen arbitrarily. By examining his geometric conventionalism, his hierarchical account of (...) science and defence of continuity in theory change, I argue that Poincaré defends a complex structuralist position based on synthetic a priori and conventional elements, the mind-dependence of which precludes epistemic access to mind-independent structures. (shrink)

How was Poincaré’s conventionalism connected to his relationism? How, in other words, is it the case that the basic principles of geometry and mechanics are, ultimately, freely chosen conventions and that, at the same time, science reveals to us the structure of the world? This lengthy study aims to address these questions by setting Poincaré’s philosophy within its historical context and by examining in detail Poincaré’s developing views about the status and role of conventions in science and the status and (...) role of relations in science. It is argued that Poincaré was a neither a rampant conventionalist nor a pure structuralist. But he was both a conventionalist and a relationist, aiming to delineate a position which allowed room for both freely, but not arbitrarily, chosen constitutive principles of science and the acquisition of objective, though, relational knowledge of the natural world. (shrink)