|Description=The following passage from [[Barseghyan (2015)|''The Laws of Scientific Change'']] summarizes the gist of the law:
<blockquote>According to ''the first law'', any element of the mosaic of accepted theories and employed methods remains in the mosaic except insofar as it is overthrown by another element or elements. Basically, the law assumes that there is certain inertia in the scientific mosaic: once in the mosaic, elements remain in the mosaic until they get replaced by other elements. It is reasonable therefore to call it ''the law of scientific inertia''.[[CiteRef::Barseghyan (2015)|p. 123]]</blockquote>
'''The First Law for Theories'''
[[File:The First Law for Theories Barseghyan 2015.jpg|center|600px]]
An accepted [[theory]] is not rejected unless there is a suitable replacement, even though sometimes that replacement may simply be the negation of the theory. For example, Issac Newton's theory of universal gravitation produced small errors in predicting the movements of the planet Mercury.[[CiteRef::Barseghyan (2015)|p. 125]] Throughout the eighteenth and early nineteenth century, it was noted that predictions of the time when the disk of Mercury would appear in transit across the sun's disk were off, sometimes by hours, or even as much as a day. These anomalies caught the attention of the French mathematician Urbain Jean Joseph Leverrier, who proposed an explanation consistent with Newton's theory in 1859. Mercury, he supposed, was being perturbed by the gravitational pull of an unknown planet orbiting closer to the sun. The hypothetical planet, named Vulcan, was searched for, but never found.[[CiteRef::Fontenrose (1973)]] Newton's theory had other predictive failures as well, but these did not lead to the rejection of the theory. It was not rejected until after 1915, when Albert Einstein showed that Mercury's movements could be explained by his new theory of gravity, the general theory of relativity.[[CiteRef::Clark (1971)]]
'''The First Law for Methods'''
[[File: The First Law for Methods Barseghyan 2015.jpg|center|600px]]
Formulated for [[method]]s, the first law states that the implicit expectations employed in theory assessment will continue to be employed until they are replaced by some alternate expectations.
|Resource=Barseghyan (2015)
|Prehistory=The logic behind first law of scientific change is comparable to that behind Newton's first law of motion. It identifies a 'null case' in which no outside forces are acting and therefore, nothing changes.