- AIM: A philosophical discussion of constructive realism and measurement in the development of nursing knowledge is presented. BACKGROUND: Through Carper's four patterns of knowing, nurses come to know a person holistically. However, measurement as a source for nursing knowledge has been criticized for underlying positivism and reductionist approach to exploring reality. Which seems mal-alignment with person-centred care. DESIGN: Discussion paper. DISCUSSION: Constructive realism bridges positivism and constructivism, facilitating the measurement of physical and psychological phenomena. Reduction of complex phenomena and theoretical constructs into measurable properties is essential to building nursing's empiric knowledge and facilitates (rather than inhibits) person-knowing. IMPLICATIONS FOR NURSING: Nurses should consider constructive realism as a philosophy to underpin their practice. This philosophy supports measurement as a primary method of inquiry in nursing research and clinical practice. Nurses can carefully select, and purposefully integrate, measurement tools with other methods of inquiry (such as qualitative research methods) to demonstrate the usefulness of nursing interventions and highlight nursing as a science.