Theory-Ladenness

Theory-ladenness is the claim that observation is never the theory-free foundation it is often assumed to be: what a scientist notices, how they describe it, and even what they perceive, are already shaped by the theoretical framework they bring to the looking. The philosopher and historian of science Norwood Russell Hanson set the idea out in his 1958 book Patterns of Discovery, arguing that two scientists holding different theories can look at the very same instrument reading and, in a meaningful sense, see something different in it. Thomas Kuhn's 1962 account of paradigm-bound normal science and Paul Feyerabend's argument that rival theories can be strictly incommensurable both build directly on Hanson's claim, and both are minted as scientist entities on this atlas. How far the claim reaches is itself contested: a strong reading holds that no observation can ever adjudicate between two sufficiently different theories, since each side may describe the very evidence differently, while a weaker and more widely accepted reading holds only that observation is coloured by theory, not that it is powerless to correct or falsify one, a distinction the atlas's own falsifiability entry depends on remaining possible at all.