Artefactual Systems, Missing Components and Replaceability

A very important practical concern of modern information systems is to make explicit, for the purpose of mutual understanding and interoperability, people's assumptions about everyday reality. This is one of the reasons behind the emergence of applied ontology as an interdisciplinary area of research, which builds on the powerful tools of formal ontology and the insights of philosophical investigation to provide useful, cognitively transparent and computationally manageable formal models, also known as (computational) ontologies. The importance of such ontologies is increasingly recognised nowadays, as a complement to standard technical documentation, especially in the (collaborative) design, production, maintenance and deployment of complex technical artefacts. Under this perspective, I will focus on an ontological puzzle that is still lively debated. When engineers or technicians speak of technical things and discuss about construction or maintenance problems, they tend to ascribe a genuine ontological status to their 'creatures', even if they do not have a physical presence. This seems to be a systematic phenomenon in the case of system components that are temporarily missing or undergo replacement. A technician would, for instance, talk about a cable that connects to a lamp in a smashed headlamp of a car, thus referring to the lamp even if it is not there anymore. This chapter will offer a practitioner-oriented ontological account of such situations, concerning objects playing the role of functional components in larger artefactual systems. I will argue that the way people refer to such objects presupposes a non-standard ontological behaviour, allowing for complete replacement and virtual presence.