Albert Einstein tentatively introduced the term ‘light quanta’ in 1905 as a “heuristic point of view”. In 1926, Gilbert N. Lewis renamed them 'photons'; ever since, the concept was (and still is) controversially discussed. How are such complex concepts formed and how do they develop? How is terminological change interlinked with the history of ideas and with mental modeling? Well-defined terms usually come chronically late, much later than vague ideas and intuitive mental models which eventually lead to them. Even after such terms are available, substantial disagreement concerning their meaning might still exist – in fact, various different, indeed conflicting mental models are often associated with one and the same concept. Light quanta are paradigmatic for such processes since clarification took unusually long in this case – hence this case allows to study this development 'in slow motion'. My claim is that we need a deeper combination of history of science with a history of terminology (Begriffsgeschichte), the history of ideas and a more cognitively oriented history of mental models in science. My talk will sketch some of the more general claims and programmatic on the basis of handpicked examples.

One persistent methodological challenge in integrated history and philosophy of science has been to demonstrate the usefulness of history of science for philosophy of science. And one fruitful way to develop philosophy of science has been to generalise from philosophy of physics (as illustrated particularly vividly by structural realism). Hence, history of science could be useful for philosophy of science provided history of science is useful for philosophy of physics. Yet, currently history of science is systematically disconnected from philosophy of physics in an influential approach by Weatherall. He tries to solve various problems from philosophy of physics (like the hole argument and the specificity question) not by history of science, but by mathematics. I argue instead that they should often be solved by history of science, even when mathematics is also involved. For this I take the specificity question (whether general relativity is specific compared to other physical theories) as a case study. I explain how it can be solved by considering a century-old debate among physicists and mathematicians. I then indicate why Weatherall preferred to discard history and seek a contemporary mathematical solution in this case: because there are too many differences between old and contemporary science, from theories known to languages used. Moreover, such kinds of discontinuities are not unique to this case, but are generalisable to other cases. Whence a general methodological conclusion: for history of science to remain useful for philosophy of science we should conversely maintain continuities or restore them.

Perspectivism has been put forward as a middle-of-the-road position between constructivism and realism. Perspectivists acknowledge that there is no “view from nowhere” and that scientific knowledge is always situated within a conceptual framework or a system of practice. At the same time, they insist that scientific knowledge is “about the world”. In this talk we will discuss whether this compromise can work with respect to the electron, which has been conceptualized from diverse perspectives. This diversity, prima facie, undermines the realist aspirations of perspectivism, since a plurality of perspectives on the electron may throw doubt upon its very identity. We will address this worry with reference to the early history of the electron. From the 1890s to the 1920s, the electron was considered from multiple, often incompatible, theoretical perspectives. For instance, in the late nineteenth century physicists conceptualized the electron from the perspective of ether theory; whereas during the 1910s and 1920s the electron was conceptualized from the perspective of the quantum theory of atomic structure. Throughout those developments, however, an expanding set of experimental situations came to be considered manifestations of the electron. This cumulative expansion of experimental situations may hold the key for understanding the variety of multiple perspectives on the electron in a realist manner, that is, as perspectives on the same ‘thing’. We will focus on the knowledge that was involved in identifying the electron across different experimental situations and ask whether that knowledge could have been sufficient for tracking the electron across shifting theoretical perspectives.

Dr Vasiliki Christine Christopoulou

Reductionist ontologies claiming to unveil the elemental structure of the world have long held a privileged position, influencing not just ontology but also epistemic and institutional relations across the sciences, and shaping power dynamics in knowledge production and dissemination.
This privileged status was evident in the dominance of nuclear and particle physics post-World War II, overshadowing other major research fields like solid state physics (later condensed matter physics). In response, non-reductionist approaches taken by solid state physicists weren’t mere ontological claims, but aimed to challenge this status asymmetry. Similarly, physics historiography has recently begun to focus more on solid state and condensed matter physics, and this paper contributes to that effort.
Following the trajectory of solid state physicists such as Brian Pippard and Philip Anderson, this paper explores the correspondence between their understanding of the structure of matter and the structure of the sciences. Leveraging lessons from solid state physics like the autonomy of macroscopic scales from their microscopic components, they advocated for a model of the sciences that preserved each discipline's intellectual autonomy, resisting the hierarchical model promoted by particle physicists.
Their engagement with the emerging field of “complexity” in the 1980s influenced another shift, from the hierarchy of science to a network model that mimicked the interacting systems studied in the complex sciences. Through these evolutions, non-reductionist approaches to matter were put to the service of establishing a structure of the sciences where condensed matter physics could play a central role in the production and advancement of knowledge.