This document discusses applying a non-linear model to understand people with stroke. It argues that humans are complex systems and cannot be fully understood through reductionism. A key aspect of non-linear systems is variability and unpredictability. They are dynamic and influenced by initial conditions. The behavior of non-linear systems cannot be determined by studying separate factors in isolation. This has implications for understanding stroke, which must be viewed as affecting a complex, non-linear system rather than separate impairments. A non-linear model provides a more accurate way to understand individuals with stroke and improve rehabilitation approaches.