In 1927, Paul Dirac first explicitly introduced the idea that electrodynamical processes can be evaluated by decomposing them into virtual (modern terminology), energy non-conserving subprocesses. This mode of reasoning structured a lot of the perturbative evaluations of quantum electrodynamics during the 1930s. Although the physical picture connected to Feynman diagrams is no longer based on energy non-conserving transitions but on off-shell particles, emission and absorption subprocesses still remain their fundamental constituents. This article will access the introduction and the initial reception (...) of this picture of subsequent transitions (PST) by conceiving of concepts, models, and their representations as tools for the practitioners. I will argue for a multi-factorial explanation of Dirac’s initial, verbally explicit introduction: the mathematical representation he had developed was highly suggestive and already partly conceptualized; Dirac was philosophical flexible enough to talk about transitions when no actual transitions, according to the general interpretation of quantum mechanics of the time, occurred; and, importantly, Dirac eventually used the verbal exposition in the same paper in which he introduced it. The direct impact of PST on the conception of quantum electrodynamical processes will be exemplified by its reflection in diagrammatical representations. The study of the diverging ontological commitments towards PST immediately after its introduction opens up the prehistory of a philosophical debate that stretches out into the present: the dispute about the representational and ontological status of the physical picture connected to the evaluation of the perturbative series of QED and QFT. (shrink)

The depths of the sea, their obscure inhabitants and their mysteries have always been a rich source of myths and metaphors for authors and philosophers. Fables about giant squids and monstrous octopuses run through the history of literature and culture. The vampire squid is only a small phylogenetic relic, but it provides a useful model for Flusser's hybrid philosophical fiction Vampyroteuthis Infernalis. Flusser slips metaphorically into the creature’s gelatinous skin in order to speculate on the paradigms of postmodern life, measuring (...) the abyss from the inside and producing a very peculiar, experimental form of thinking and writing. In the present era of virtual reality and computer simulations, we experience fiction as the only reality. According to Vaihinger's definition, fiction is a useful construct that is precisely not real, but enables human beings to create and manipulate their environments. His philosophy of “as if” is perhaps the fullest expression of fictionalism and shows its ambivalent potential. (shrink)