Uniformitarianism

The actualism (from the Latin actualis, " really "), even actuality principle of uniformity or Gleichförmigkeitsprinzip, English uniformitarianism, the basic scientific method in geology.

General

The principle of uniformity of processes states that geologic processes that can be observed today, have worked well in the past. So there are direct conclusions of today's processes on educational processes possible in the past. For example, if you find fossil ripple marks in fossil strata, the same recent sedimentary structures, we may assume that they were formed by exactly the same operations as these.

Thus, the actualism is a special case of a general scientific rule, the simplicity principle. It states that you should use no additional or unknown causes to explain a phenomenon known causes long enough for that. The opposite of actualistic method is called exceptionalism.

More generally adopted is the axiom of the uniformity of the laws. In this case, it is believed that anywhere and at any time governed by the same laws of nature and have prevailed. Like every axiom in principle it is not provable, but without this assumption might scientific work impossible from the outset.

Lyell's counter-model to catastrophism

These ideas were first formulated in 1785 by James Hutton ( 1726-1797 ) in his book Theory of the Earth, and then further developed by Charles Lyell in his major work, Principles of Geology ( 1830). However, Lyell confounded these methodological approaches that were never even questioned by his opponents in swift (but illegal ) way with his theory of the uniformity of the changes ( gradualism ). In contrast to the then still prevailing explanatory model of catastrophism Lyell believed that it would never have occurred in Earth's history to periods of increased geological activity, such as increased volcanism, mountain building phases or a special batches accelerated development of living beings. Even comprehensive upheavals of the earth are only to be explained by the slow accumulation of many small events that would have gradually, over vast ages, accumulated. Likewise, Lyell took the uniformity of conditions. For example, he disagreed with the then (and now ) current view which earth must be solidified from a once red-hot molten state, claiming an ever- constant ratio between continental crust and ocean basins.

On the basis of Lyell's rhetorical skill his gradualist views were quickly adopted by a large body, and especially Georges Cuvier katastrophistische Kataklysmentheorie was almost completely suppressed as early as 1850. Although Charles Darwin in his theory of evolution also took a very slow evolution of organisms in imperceptibly small steps and thus contributed significantly to the general acceptance of gradualism, it cost Lyell way, very hard to accept Darwin's theory. In his opinion, the emergence of entirely new biological species implied a much too large (because irreversible ) change over the course of Earth's history. Only towards the end of his life, Lyell gave way under the crushing burden of evidence and Darwin joined the theory of the directed evolution of living creatures on. Similarly, Lyell saw later forced to acknowledge the Ice Age theory of Louis Agassiz. This turned in his exploration of the glacier likewise clear actualistic methods, but remained as a pupil of Cuvier followers of a catastrophe theory.

Limits of uniformity

Lyell's early contemporary of Karl Ernst Adolf von Hoff recognized in his work history has been proven by tradition, natural variations in the earth's surface (1822-1834) that the actualism as a scientific method is indeed inevitable, but that it occasionally comes across as theory to its limits. Hoff was of the opinion that sometimes have specific hypotheses to explain past processes are expected to be used, but only if the observations of current operations and powers are not sufficient. However, due to the success of such approaches Lyell'schen gradualism came largely forgotten.

Only in the course of the 1960s and 70s put various authors, such as Reijer Hooykaas, Stephen Jay Gould, Martin Rudwick and R. Porter, and critically with the ambiguous Gleichförmigkeitsbegriff apart, they rebuttable particularly the separation of the ( axiomatic ) method of the ( ) theory worked out. This in consequence facilitated the "renaissance" of katastrophistischen theories about the history of the earth, such as the interpretation of the global iridium anomaly as the result of a meteor impact at the Cretaceous-Tertiary boundary.

An example of the limits of the actual actualistic method returns the interpretation of archaic tectonics. For this purpose it is necessary to resort to laboratory experiments, because in Archean rocks of the earth's crust had not yet separated in the today observed continental and oceanic crusts, thus could not even behave according to the laws of acting today tectonics. Similarly, the oxygen content was so low that it could form huge deposits of iron minerals as a result, those whose education would be completely ruled today Banded Iron Formations in the archaic atmosphere. In general, with increasing distance from the presence of a actualistic interpretation of geoscientific evidence is increasingly uncertain.