rather than inventing extra esoteric or unknown processes without good reason'',, "Strict uniformitarianism may often be a guarantee against pseudo-scientific phantasies and loose conjectures, but it makes one easily forget that the principle of uniformity is not a law, not a rule established after comparison of facts, but a methodological principle, preceding the observation of facts ... It is the logical principle of parsimony of causes and of the economy of scientific notions. By explaining past changes by analogy with present phenomena, a limit is set to conjecture, for there is only one way in which two things are equal, but there is an infinity of ways in which they could be supposed different." otherwise known as parsimony or Occam's razor. Substantive hypotheses The substantive hypotheses were controversial and, in some cases, accepted by few. These hypotheses are judged true or false on empirical grounds through scientific observation and repeated experimental data. This is in contrast with the previous two philosophical assumptions that come before one can do science and so cannot be tested or falsified by science. Uniformity of rate across time and space: Change is typically slow, steady, and gradual. Uniformity of rate (or gradualism) is what most people (including geologists) think of when they hear the word "uniformitarianism," confusing this hypothesis with the entire definition. As late as 1990, Lemon, in his textbook of stratigraphy, affirmed that "The uniformitarian view of earth history held that all geologic processes proceed continuously and at a very slow pace." Gould explained Hutton's view of uniformity of rate; mountain ranges or grand canyons are built by the accumulation of nearly insensible changes added up through vast time. Some major events such as floods, earthquakes, and eruptions, do occur. But these catastrophes are strictly local. They neither occurred in the past nor shall happen in the future, at any greater frequency or extent than they display at present. In particular, the whole earth is never convulsed at once. Uniformity of state across time and space''': Change is evenly distributed throughout space and time. The uniformity of state hypothesis implies that throughout the history of our earth there is no progress in any inexorable direction. The planet has almost always looked and behaved as it does now. Change is continuous but leads nowhere. The earth is in balance: a dynamic steady state. 20th century Stephen Jay Gould's first scientific paper, "Is uniformitarianism necessary?"