Duhem–Quine thesis

[1][2] It is named after French theoretical physicist Pierre Duhem and American logician Willard Van Orman Quine, who wrote about similar concepts.

Later theories of physics and astronomy, such as classical and relativistic mechanics could account for such observations without positing a fixed Earth, and in due course they replaced the static-Earth auxiliary hypotheses and initial conditions.

[5] In particular, some prominent philosophers, most notably Cesare Cremonini, refused to look through the telescope, arguing that the instrument itself might have introduced artefacts that produced the illusion of mountains or satellites invisible to the naked eye.

In the early 17th century the modern version of the Duhem–Quine thesis had not been formulated, but common sense objections to such elaborate and ad hoc implicit auxiliary assumptions were urged.

The behaviour of telescopes on Earth denied any basis for arguing that they could create systematic artefacts in the sky, such as apparent satellites that behaved in the predictable manner of Jovian moons.

Evidence also offered no basis to suggest that they could present yet other, more elaborate artefacts, fundamentally different from the satellites, such as lunar mountains that cast shadows varying consistently with the direction of solar illumination.

In practice the politics and theology of the day determined the result of the dispute, but the nature of the controversy was a clear example of how different bundles of (usually implicit) auxiliary assumptions could support mutually inconsistent hypotheses concerning a single theory.

As popular as the Duhem–Quine thesis may be in philosophy of science, in reality Pierre Duhem and Willard Van Orman Quine stated very different theses.