Purpose - The current state of theory-building in the field of operations and supply chain management (OSCM) is in a strong need of rigorous, empirically based theories that enhance understanding of the causal relationships between the structural elements and properties of the business processes. In this research note the authors propose the critical realism (CR) philosophy of science as a particularly suitable philosophical position (not to the exclusion of others) to review the mechanisms of OSCM knowledge generation and to provide philosophical grounding and methodological guidance for both OSCM theory building and testing. Design/methodology/approach - To demonstrate potential benefits of CR-based structured approach to knowledge generation in OSCM research, this conceptual paper uses a case study that illustrates the adoption of one of the OSCM theories - i.e. the theory of swift, even flow. Findings - CR interprets the accumulated empirical information about OSCM phenomena as observable manifestations of the underlying causal mechanisms that cannot be perceived otherwise. CR can provide epistemological support to the choice of performance measures that manifest the underlying causal mechanisms of interest. Extensive accumulation of empirical data from multiple innovative sources will not dramatically add to understanding of the system under investigation, unless and until the underlying causal mechanisms that trigger the observed behaviour are identified and tested. The CR abductive mode of reasoning emphasises the role of uncertainty in complex process behaviours and can facilitate enrichment and refutation of OSCM theories. Originality/value - CR has a clear potential to contribute to OSCM research by enabling better understanding of causal relationships underlying complex behaviours of different elements of business process by providing robust and relevant mechanisms of generating knowledge about business processes that explicitly link empirical and causal aspects of theory building and testing.