Kuhn-1962-structure-of-scientific-revolutions opens by arguing that studying the history of science presents a different concept of science than what traditional science is thought to be.
Kuhn describes the traditional linear view of scientific progress development-by-accumulation as a growing collection of facts, laws, theories and methods, to which individual scientists contribute to incrementally. On this view, scientific progress is additive, and the historians task is to trace when each correct element was discovered and the obstacles that delayed the progress.
Kuhn argues that this traditional model causes problems for historians, such as how to determine when a particular discovery was first discovered and by whom (see phlogiston vs. oxygen). Another problem is how to grapple with past out-of-date beliefs, such as Aristotelian physics.
Either past theories must be dismissed as myths produced by the same sort of scientific methods we use now, or they must be treated as genuine science despite being incompatible with current knowledge.
Accepting the second option implies that science has, at different times, relied on fundamentally different and incompatible frameworks. This conclusion directly challenges the traditional additive picture of scientific progress and motivates Kuhn’s alternative, non-linear account of scientific change.