Issues related to nursing epistemology are reviewed. This review includes discussion of logical positivism, empiricism and interpretive-emancipatory paradigms, their influence on the construction of knowledge and on its methods of derivation and verification. Changes in the conceptualisation of science are explored, and scientific realism is introduced as a contemporary philosophy of science through which the discipline of nursing can develop. Questions surrounding the development of nursing knowledge are examined; for example, the implications of theory construction through the use of borrowed theory and the acceptance of external philosophies of science. Argument is offered for and against borrowing external theories and philosophies, or developing theories and philosophies from research into nursing practice. The relationship between research method and the phenomenon under study is discussed. The need to develop a broad base of nursing knowledge through diverse research methods is addressed. Links are created between the development of non-practice-based theories, the derivation of knowledge a priori, and the poor use of nursing theory and research in nursing practice. It is suggested that nursing science should develop through a dialectic between nursing research and practice, and that such a dialectic could assist the forward movement of nursing through the evolution of meaningful nursing theories and philosophies of nursing science.