Thomas Kuhn argues that science operates in two distinct modes: normal science and scientific revolution. During normal science, scientists work within a shared paradigm that provides the framework and assumptions for their research. The paradigm guides what phenomena can be explained, what problems are worth studying, and how research is conducted. However, over time anomalies and resistant problems emerge that the paradigm cannot resolve, leading to a crisis and eventual shift to a new paradigm during a period of scientific revolution.