This study, presenting a history of the measurement of light intensity from its first hesitant emergence to its gradual definition as a scientific subject, explores two major themes. The first concerns the adoption by the evolving physics and engineering communities of quantitative measures of light intensity around the turn of the twentieth century. The mathematisation of light measurement was a contentious process that hinged on finding an acceptable relationship between the mutable response of the human eye and the more (...) easily stabilised, but less encompassing, techniques of physical measurement. -/- A second theme is the exploration of light measurement as an example of ‘peripheral science’. Among the characteristics of such a science, I identify the lack of a coherent research tradition and the persistent partitioning of the subject between disparate groups of practitioners. Light measurement straddled the conventional categories of ‘science’ and ‘technology’, and was influenced by such distinct factors as utilitarian requirements, technological innovation, human perception and bureaucratisation. Peripheral fields such as this, which may be typical of much of modern science and technology, have hitherto received little attention from historians. -/- These themes are pursued with reference to the social and technological factors which were combined inextricably in the development of the subject. The intensity of light gained only sporadic attention until the late nineteenth century. Measured for the utilitarian needs of the gas lighting industry from the second half of the century, light intensity was appropriated by members of the nascent electric lighting industry, too, in their search for a standard of illumination. By the turn of the century the ‘illuminating engineering movement’ was becoming an organised, if eclectic, community which promoted research into and standards for the measurement of light intensity. -/- The twentieth-century development of the subject was moulded by organisation and institutionalisation. Between 1900 and 1920, the new national and industrial laboratories in Britain, America and Germany were crucial in stabilising the subject. In the inter-war period, committees and international commissions sought to standardise light measurement and to promote research. Such government- and industry-supported delegations, rather than academic institutions, were primarily responsible for the ‘construction’ of the subject. Practitioners increasingly came to interpret the three topics of photometry (visible light measurement), colorimetry (the measurement of colour) and radiometry (the measurement of invisible radiations) as aspects of a broader study, and enthusiastically applied them to industrial and scientific problems. -/- From the 1920s, the long-established visual methods of observation were increasingly replaced by physical means of light measurement, a process initially contingent on scientific fashion more than demonstrated superiority. New photoelectric techniques for measuring light intensity engendered new commercial instruments, a trend which accelerated in the following decade when photometric measurement was applied with limited success to a range of industrial problems. Seeds sowed in the 1920s – namely commercialisation and industrial application, the transition from visual to ‘physical’ methods, and the search for fundamental limitations in light measurement – gave the subject substantially the form it was to retain over the next half-century. (shrink)

⦿ In my dissertation I introduce, motivate and take the first steps in the implementation of, the project of naturalising modal metaphysics: the transformation of the field into a chapter of the philosophy of science rather than speculative, autonomous metaphysics. -/- ⦿ In the introduction, I explain the concept of naturalisation that I apply throughout the dissertation, which I argue to be an improvement on Ladyman and Ross' proposal for naturalised metaphysics. I also object to Williamson's proposal that modal metaphysics (...) --- or some view in the area --- is already a quasi-scientific discipline. -/- ⦿ Recently, some philosophers have argued that the notion of metaphysical modality is as ill defined as to be of little theoretical utility. In the second chapter I intend to contribute to such skepticism. First, I observe that each of the proposed marks of the concept, except for factivity, is highly controversial; thus, its logical structure is deeply obscure. With the failure of the "first principles" approach, I examine the paradigmatic intended applications of the concept, and argue that each makes it a device for a very specific and controversial project: a device, therefore, for which a naturalist will find no use for. I conclude that there is no well-defined or theoretically useful notion of objective necessity other than logical or physical necessity, and I suggest that naturalising modal metaphysics can provide more stable methodological foundations. -/- ⦿ In the third chapter I answer a possible objection against the in-principle viability of the project: that the concept of metaphysical modality cannot be understood through the philosophical analysis of any scientific theory, since metaphysical necessity "transcends'' natural necessity, and science only deals with the latter. I argue that the most important arguments for this transcendence thesis fail or face problems that, as of today, remain unsolved. -/- ⦿ Call the idea that science doesn't need modality, "demodalism''. Demodalism is a first step in a naturalistic argument for modal antirealism. In the fourth chapter I examine six versions of demodalism to explain why a family of formalisms, that I call "spaces of possibility'', are (i) used in a quasi-ubiquitous way in mathematised sciences (I provide examples from theoretical computer science to microeconomics), (ii) scientifically interpreted in modal terms, and (iii) used for at least six important tasks: (1) defining laws and theories; (2) defining important concepts from different sciences (I give several examples); (3) making essential classifications; (4) providing different types of explanations; (5) providing the connection between theory and statistics, and (6) understanding the transition between a theory and its successor (as is the case with quantisation). -/- ⦿ In fifth chapter I propose and defend a naturalised modal ontology. This is a realism about modal structure: my realism about constraints. The modal structure of a system are the relationships between its possible states and between its possible states and those of other systems. It is given by the plurality of restrictions to which said system is subject. A constraint is a factor that explains the impossibility of a class of states; I explain this concept further. First, I defend my point of view by rejecting some of its main rivals: constructive empiricism, Humean conventionalism, and wave function realism, as they fail to make sense of quantum chaos. This is because the field requires the notion of objective modal structure, and the mentioned views have trouble explaining the modal facts of quantum dynamics. Then, I argue that constraint realism supersedes these views in the context of Bohm's standard theory and mechanics, and underpins the study of quantum chaos. Finally, I consider and reject two possible problems for my point of view. -/- ⦿ A central concern of modal metaphysicians has been to understand the logical system that best characterises necessity. In the sixth chapter I intend to recover the logical project applied to my naturalistic modal metaphysics. Scientists and philosophers of science accept different degrees of physical necessity, ranging from purely mathematically necessary facts that restrict physical behaviour, to kinetic principles, to particular dynamical constraints. I argue that this motivates a multimodal approach to modal logic, and that the time dependence of dynamics motivates a logic of historical necessity. I propose multimodal propositional (classical) logics for Bohmian mechanics and the Everettian theory of many divergent worlds, and I close with a criticism of Williamson's approach to the logic of state spaces of dynamic systems. (shrink)