This article treats the philosophical underpinnings of the notions of ubiquity and pervasive computing from a historical perspective. The current focus on these notions reflects the ever increasing impact of new media and the underlying complexity of computed function in the broad sense of ICT that have spread vertiginiously since Mark Weiser coined the term ‘pervasive’, e.g., digitalised sensoring, monitoring, effectuation, intelligence, and display. Whereas Weiser’s original perspective may seem fulfilled since computing is everywhere, in his and Seely Brown’s (1997) terms, ‘invisible’, on the horizon, ’calm’, it also points to a much more important and slightly different perspective: that of creative action upon novel forms of artifice. Most importantly for this article, ubiquity and pervasive computing is seen to point to the continuous existence throughout the computational heritage since the mid-20th century of a paradoxical distinction/complicity between the technical organisation of computed function and the human Being, in the sense of creative action upon such function. This paradoxical distinction/complicity promotes a chiastic (Merleau-Ponty) relationship of extension of one into the other. It also indicates a generative creation that itself points to important issues of ontology with methodological implications for the design of computing. In this article these implications will be conceptualised as prosopopoietic modeling on the basis of Bernward Joerges introduction of the classical rhetoric term of ’prosopopoeia’ into the debate on large technological systems. First, the paper introduces the paradoxical distinction/complicity by debating Gilbert Simondon’s notion of a ‘margin of indeterminacy’ vis-a-vis computing. Second, it debates the idea of
prosopopoietic modeling, pointing to a principal role of the paradoxical distinction/complicity within the computational heritage in three cases:

a. Prosopopoietic aspects of John von Neumann’s First Draft of a Report on the EDVAC from
1945.
b. Herbert Simon’s notion of simulation in The Science of the Artificial from the 1970s.
c. Jean-Pierre Dupuy’s idea of ‘verum et factum convertuntur’ from the 1990s.

Third it concludes with a brief re-situating of Weiser’s notion of pervasive computing on the basis of this background.