Keen (1980) and Churchman (1996), among others, have called for the use of philosophy as a reference discipline for information systems research, the objective being to produce more imaginative, reflective and diverse studies and hence a broader knowledge base for IS theory. This paper describes how Churchman’s inquiring systems may be used as a basis for IS studies, and further describes five roles (as defined by Hodges 1995) that philosophy may play in informing IS research.