Begin Exact Quote (Gould 1984, p. 11):
METHODOLOGICAL PRESUPPOSITIONS ACCEPTED BY ALL SCIENTISTS
1) The Uniformity of law - Natural laws are invariant in space and time. John Stuart Mill (1881) argued that such a postulate of uniformity must be invoked if we are to have any confidence in the validity of inductive inference; for if laws change, then an hypothesis about cause and effect gains no support from repeated observations - the law may alter the next time and yield a different result. We cannot "prove" the assumption of invariant laws; we cannot even venture forth into the world to gather empirical evidence for it. It is an a priori methodological assumption made in order to practice science; it is a warrant for inductive inference (Gould, 1965).
End Exact Quote (Gould 1984, p. 11)
Gould, Stephen Jay. "Toward the vindication of punctuational change."Catastrophes and earth history (1984): 9-16.
also see:
Gould, Stephen Jay. "Is uniformitarianism necessary?" American Journal of Science 263.3 (1965): 223-228.
Gould, Stephen Jay. Time's arrow, time's cycle: Myth and metaphor in the discovery of geological time. Harvard University Press, 1987.