We have no aces to what the world is, to ontology, only to descriptions of the world... that is to say, epistemology... We should never say something in the world: 'it is a system'; only: it may be described as a system'.
Checkland 1983, p. 671 cited in Stephen K. Probert (1998) "The Metaphysical Foundations of Soft and Hard Information Systems Methodologies". In: Robert Macredie (1998) Modelling for Added Value. p. 86