Michael Heidelberger

The main claim of this talk is that mathematical physics and philosophy of physics are not different. This claim, so formulated, is obviously false because it is overstated; however, since no non-tautological statement is likely to be completely true, it is a meaningful question whether the overstated claim expresses some truth. I hope it does, or so I’ll argue. The argument consists of two parts: First I’ll recall some characteristic features of von Neumann’s work on mathematical foundations of quantum mechanics and will claim that von Neumann’s motivation and results are essentially philosophical in their nature; hence, to the extent von Neumann’s work exemplifies what is considered to be mathematical physics, mathematical physics appears as formally explicit philosophy of physics. The second argument is based on a rather trivial interpretation of what mathematical physics is. That interpretation implies that mathematical physics shares some key characteristic features with philosophy of physics which make the two almost indistinguishable.

In the 19th century, "Psychophysical Parallelism" was the most popular solution of the mind-body problem among physiologists, psychologists and philosophers. (This is not to be mixed up with Leibnizian and other cases of "Cartesian" parallelism.) The fate of this non-Cartesian view, as founded by Gustav Theodor Fechner, is reviewed. It is shown that Feigl's "identity theory" eventually goes back to Alois Riehl who promoted a hybrid version of psychophysical parallelism and Kantian mind-body theory which was taken up by Feigl's teacher Moritz Schlick.

It is widely held that the current debate on the mind-body problem in analytic philosophy began during the 1950s at two distinct sources: one in America, de- riving from Herbert Feigl's writings, and the other in Australia, related to writings by U. T. Place and J. J. C. Smart (Feigl [1958] 1967). Jaegwon Kim recently wrote that "it was the papers by Smart and Feigl that introduced the mind-body problem as a mainstream metaphysical Problematik of analytical philosophy, and launched the debate that has continued to this day" (Kim 1998, 1). Nonetheless, it is not at all obvious why these particular articles sparked a debate, nor why Feigl's work in particular came to play such a prominent part in it, nor how and to what extent Feigl's approach rests on the logical empiricism he endorsed

In 1874, the French philosopher Émile Boutroux wrote a dissertationon the contingency of the laws of nature that highly influenced academic philosophy during the French Third Republic and led to a more hypothetical view of the natural sciences and mathematics. Boutroux took over the concept of contingency from the neo-Kantian philosopher Eduard Zeller who had insisted against Hegel on the role of contingency in history, and carried it over to nature. From this he tried to show that the sciences are hierarchically structured such that each layer is irreducible to its more basic predecessor. He also distinguished between two kinds of natural laws in a way very similar to Nancy Cartwright in the1980s. It is finally shown that Boutroux’s view on the nature of mathematics as a hypothetical science had a strong impact on Poincaré.

This article deals with Moritz Schlick's critical realism and its sources that dominated his philosophy until about 1925. It is shown that his celebrated analysis of Einstein's relativity theory is the result of an earlier philosophical discussion about space perception and its role for the theory of space. In particular, Schlick's "method of coincidences" did not owe anything to "entirely new principles" based on the work of Einstein, Poincaré or Hilbert, as claimed by Michael Friedman, but was already in place before these principles were developed. The first part of the article is devoted to Alois Riehl's critical realism—a neo-Kantian variant which rejects the dominant interpretation of the thing-in-itself as a mere limiting concept and takes empirical theories of space perception into consideration. The second part deals with the central role of "Psychological Parallelism" for Riehl and its integration with Kant's epistemology. In the third part it is shown that Schlick's theory of knowledge is based on Riehl's intricate reworking of Kantian epistemology, physiological psychology, theory of sense perception and philosophy of mathematics. The conclusion stresses the position of the unity of consciousness in Riehl's philosophy which Schlick admittedly cannot cope with

Since the late 1950s one of the most important and influential views of post-positivist philosophy of science has been the theory-ladenness of observation. It comes in at least two forms: either as a psychological law pertaining to human perception (whether scientific or not) or as conceptual insight concerning the nature and functioning of scientific language and its meaning. According to its psychological form, perceptions of scientists, as perceptions of humans generally, are guided by prior beliefs and expectations, and perception has a peculiar holist character. In its conceptual form it maintains that scientists’ observations rest on the theories they accept and that the meaning of the observational terms involved depends upon the theoretical context in which they occur. Frequently, these two versions are combined with each other and give rise to a constructivist view of scientific knowledge (I shall use the term “constructivism” roughly in the same way as Golinski [1998, chap. 1]). According to this outlook, our experience is categorized and preconditioned by prior belief since the process of gaining knowledge through science always involves the use of concepts from some theory or other. This view can easily be strengthened to serve as the cornerstone of a constructivist and anti-empiricist account of science: The categories in terms of which we carve up our experience are not read off from the external world but follow from prior theoretical commitments.

Alan Richardson, one of the editors of the present volume, dryly remarks in a footnote to the introduction: “Logical empiricism remains alive in philosophical memory chiefly by the significance of its death.” I think that this pertinent paradox can be enlarged to generally characterise the relation of present-day philosophy of science to logical empiricism : the more philosophy of science has struggled in the past to distance itself from central tenets of the movement of LE, the more it had to realise how close and how indebted it remains to LE and how much “post-positivism” itself willy-nilly keeps its spirit alive. Thus, there is the growing feeling that the identity of today’s philosophy of science is much more closely tied to LE, many manifestations to the contrary notwithstanding. The renewed interest in LE that has resulted from this insight must necessarily have lead to repercussions also on the appraisal of LE as a philosophical position. The once almost unanimous and rash condemnation of LE in the sixties and seventies is today followed by a prudent and broad-minded second look that tries to do fuller justice to the historical background and development. One can understand that for some of those who take the foregoing considerations seriously the news of LE’s death seems to be a little premature