The article contributes to the theoretical discussion of the epistemological grounds of triangulation in nursing research. In nursing research, the combination of qualitative and quantitative methods is being used increasingly. The attempt to relate different kinds of data through triangulation of different methods is a challenging task as data derived through different methodologies are viewed as incommensurable. Epistemological questions become a vital issue in triangulation of different methods, as qualitative and quantitative methods are built on philosophical differences in the structure and confirmation of knowledge. The epistemology of nursing is manifold, complex and multifarious in character. Contemporary nursing research should be developed on the bases of an epistemology that reflects this multiplicity. The benefits and problems of triangulation are discussed on basis of an epistemological position that acknowledges the need for various types of knowledge and that does not attempt to rank them in a hierarchical order or place different values on them. We conclude that the complexity and diversity of reality provides the ontological basis for an alternative epistemological position. The various methods used should be recognized as springing from different epistemological traditions which, when combined, add new perspectives to the phenomenon under investigation. The different types of knowledge should not be seen as ranked, but as equally valid and necessary to obtain a richer and more comprehensive picture of the issue under investigation.
