From the classical conceptualisations and discourses of Aristotle and Plato to the disturbing situatedness of the existentialists, philosophy provides perspectives on aspects of existence, thought and knowledge that illuminate and explain as well as connecting the somewhat specialised and inaccessible theory of software and systems engineering to the wider consciousness. This paper summarises the positions of selected philosophers that have been interpreted by some influential authors in software engineering to strengthen their arguments and in turn influence software methodology. Consideration of these philosophical perspectives can usefully influence the design of research projects and the analysis of results, particularly where the enquiry involves the business, industrial and other situated contexts in which contemporary system design and development is done.