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Uniformitarianism

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Uniformitarianism, in the philosophy of science, assumes that the same natural processes that operate in the universe now, have always operated in the universe in the past, and at the same rates; and that the same laws of physics apply everywhere in the universe. Its methodology is frequently summarized as "the present is the key to the past," because it holds that all things continue as they were from the beginning of the world.

The concept of uniformity in geological processes can be traced back to the Persian geologist, Avicenna (Ibn Sina), in The Book of Healing, published in 1027.[1][2] Modern uniformitarianism was formulated by Scottish naturalists in the late 18th century, starting with the work of the geologist, James Hutton, which was refined by John Playfair and popularised by Charles Lyell's Principles of Geology in 1830.[3] The term uniformitarianism was coined by William Whewell, who also coined the term catastrophism for the idea that the Earth was shaped by a series of sudden, short-lived, violent events.[4]

Elements of uniformitarianism

According to Reijer Hooykaas (1963), uniformitarianism is a family of four related propositions, not a single idea:[5]

  • Uniformity of law – the laws of nature are constant.
  • Uniformity of methodology – the appropriate hypotheses for explaining the geological past are those with analogy today.
  • Uniformity of kind – past and present causes are all of the same kind, have the same energy, and produce the same effects.
  • Uniformity of degree – geological circumstances have not changed over time.

None of these connotations requires another, and they are not all equally inferred by uniformitarians.[6]

Stephen Jay Gould's first scientific paper, Is uniformitarianism necessary? (1965), reduced these four interpretations to two, methodological and substantive uniformitarianism[7]. He dismissed the first principle, which asserted spatial and temporal invariance of natural laws, as no longer an issue of debate. He rejected the second as an unjustified limitation on scientific inquiry, as it constrains past geologic rates and conditions to those of the present. Later, Gould expanded on these related propositions in Time's Arrow, Time's Cycle (1987), stating that Lyell conflated two different types of propositions: a pair of methodological assumptions with a pair of substantive hypotheses.[8]

Methodological assumptions:

  • Uniformity of law: Natural laws are constant across space and time.[9]
  • Uniformity of process: If a past phenomenon can be understood as the result of a process now acting in time and space, do not invent an extinct or unknown cause as its explanation.[10]

Substantive hypotheses:

  • Uniformity of rate: Change is typically slow, steady, and gradual.[10]
  • Uniformity of state: Change is evenly distributed throughout space and time.[11]

Methodological assumptions

The methodological assumptions are universally acclaimed by scientists, and embraced by all geologists. Gould further states that these philosophical propositions must be assumed before you can proceed as a scientist doing science. "You cannot go to a rocky outcrop and observe either the constancy of nature's laws or the working of unknown processes. It works the other way around." You first assume these propositions and "then you go to the out crop of rock."[10]

The axiom of uniformity of law is necessary in order for scientists to extrapolate inductive inference into the unobservable past. As James Hutton wrote: “If the stone, for example, which fell today, were to rise again tomorrow, there would be an end of natural philosophy, our principles would fail, and we would no longer investigate the rules of nature from our observations.”[12] In essence, the constancy of natural laws must be assumed in our study of the past, because if we do not, then we cannot meaningfully study the past. Making inferences about the past is wrapped up in the difference between studying the observable present and the unobservable past. In the observable present, induction can be regarded as self-corrective. That is to say, our erroneous beliefs about the observable world can be proven wrong and corrected by other observations. This is Popper's principle of falsifiability. However, past processes are not observable by their very nature. Therefore, in order to come to conclusions about the past, we must assume the invariance of nature's laws.[9]

Substantive hypotheses

The substantive hypotheses were controversial and, in some cases, accepted by few.[8] These hypotheses are judged true or false on empirical grounds through scientific observation and repeated experimental data. This is in contrast with the philosophical assumptions[10] that come before one can do science and so cannot be tested or falsified by science.

The uniformity of state hypothesis (i.e. steadystateism) 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. [11]

These divisions have been opposed by later geologists such as Celâl Şengör.[citation needed]

History of Uniformitarianism

The concept of uniformitarianism in geology was first proposed in the 11th century by the Persian geologist, Avicenna (Ibn Sina, 980-1037), who provided the first uniformitarian explanations for geological processes in The Book of Healing. He observed that mountains were formed after a long sequence of events that predate human existence.[1][2] While discussing the formation of mountains, he explained:

"Either they are the effects of upheavals of the crust of the earth, such as might occur during a violent earthquake, or they are the effect of water, which, cutting itself a new route, has denuded the valleys, the strata being of different kinds, some soft, some hard... It would require a long period of time for all such changes to be accomplished, during which the mountains themselves might be somewhat diminished in size."[2]

Later in the 11th century, the Chinese naturalist, Shen Kuo, also recognized the concept of 'deep time'.[13]

After The Book of Healing was translated into Latin in the 12th century, a few other scientists also reasoned in uniformitarian terms, but the principle was not uniformly accepted until the late 18th century.[1] The uniformitarian explanation of the formation of sedimentary rock in geological time was supported by the 18th-century father of geology, James Hutton and popularized by Charles Lyell. In the 18th and 19th centuries, the debate between the two theories was intense, as the interpretations of uniformitarianism clashed with the prevailing religious beliefs.

Uniformitarianism and Catastrophism

Uniformitarianism is a basic principle of modern geology. It was originally proposed in contrast to catastrophism, which states that the distant past "consisted of epochs of paroxysmal and catastrophic action interposed between periods of comparative tranquility"[14] Especially in the late 19th and early 20th centuries, a number of geologists took this interpretation to mean that catastrophic events are not important in geologic time; one example of this is the debate of the formation of the Channeled Scablands due to the catastrophic Missoula glacial outburst floods. An important result of this debate and others was the re-clarification that, while the same principles operate in geologic time, catastrophic events that are infrequent on human time-scales can have important consequences in geologic history.

“Geologists do not deny uniformitarianism in its true sense, that is to say, of interpreting the past by means of the processes that are seen going on at the present day, so long as we remember that the periodic catastrophe is one of those processes. Those periodic catastrophes make more showing in the stratigraphical record than we have hitherto assumed.”[15]

Even Charles Lyell thought that ordinary geological processes would cause Niagara Falls to move upstream to Lake Erie within 10,000 years, leading to catastrophic flooding of a large part of North America.

Unlike Lyell, modern geologists do not apply uniformitarianism in the same way. They question if rates of processes were uniform through time and only those values measured during the history of geology are to be accepted.[16] The present may not be a long enough key to penetrate the deep lock of the past.[17] Geologic processes may have been active at different rates in the past that humans have not witnessed. Thus the current scientific consensus is that Earth's history is a slow, gradual process punctuated by occasional natural catastrophic events that have affected Earth and its inhabitants.[18]

Uniformitarianism is a generalization of the principle of actualism (geology), which states that all past geological action was like all present geological action. The principle of actualism is the cornerstone of paleoecology.

See also

Notes

  1. ^ a b c Munim M. Al-Rawi and Salim Al-Hassani (2002). "The Contribution of Ibn Sina (Avicenna) to the development of Earth sciences" (PDF). FSTC. Retrieved 2008-07-01. {{cite web}}: Unknown parameter |month= ignored (help)
  2. ^ a b c Stephen Toulmin and June Goodfield (1965), The Ancestry of Science: The Discovery of Time, p. 64, University of Chicago Press (cf. The Contribution of Ibn Sina to the development of Earth sciences)
  3. ^ Uniformitarianism: World of Earth Science
  4. ^ Concept of Uniformitarianism
  5. ^ Reijer Hooykaas, Natural Law and Divine Miracle: The Principle of Uniformity in Geology, Biology, and Theology, Leiden: EJ Brill, 1963.
  6. ^ David Cahan, 2003, From Natural Philosophy to the Sciences, p 95 ISBN 9780226089287.
  7. ^ Gould, S. J. 1965. Is uniformitarianism necessary? American Journal of Science 263: pp. 223–228.
  8. ^ a b Gould, Stephen J (1987). Time’s Arrow, Time’s Cycle: Myth and Metaphor in the Discovery of Geological Time. Cambridge, MA: Harvard University Press. p. 118.
  9. ^ a b Gould, Stephen J (1987). Time’s Arrow, Time’s Cycle: Myth and Metaphor in the Discovery of Geological Time. Cambridge, MA: Harvard University Press. p. 119.
  10. ^ a b c d Gould, Stephen J (1987). Time’s Arrow, Time’s Cycle: Myth and Metaphor in the Discovery of Geological Time. Cambridge, MA: Harvard University Press. p. 120.
  11. ^ a b Gould, Stephen J (1987). Time’s Arrow, Time’s Cycle: Myth and Metaphor in the Discovery of Geological Time. Cambridge, MA: Harvard University Press. p. 123.
  12. ^ Hutton, J (1795). Theory of the Earth with Proofs and Illustrations. p. 297.
  13. ^ Sivin, Nathan (1995). Science in Ancient China: Researches and Reflections. Brookfield, Vermont: Ashgate Publishing Variorum series. III, 23–24. {{cite book}}: Unknown parameter |nopp= ignored (|no-pp= suggested) (help)
  14. ^ William J. Whewell, Principles of Geology, Charles Leyell, vol. II, London, 1832: Quart. Rev., v. 47, p. 103-123.
  15. ^ Ager, Derek V. (1993). The Nature of the Stratigraphical Record, 3rd Ed. Chichester, New York, Brisbane, Toronto, Singapore: John Wiley & Sons. pp. 83–84. ISBN 0471938084.
  16. ^ Smith, Gary A, (2006). How Does Earth Work: Physical geology and the Process of Science (textbook). New Jersey: Pearson/Prentice Hall. p. 12. ISBN 0130341290. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: extra punctuation (link) CS1 maint: multiple names: authors list (link)
  17. ^ Ager, Derek V. (1993). The Nature of the Stratigraphical Record, 3rd Ed. Chichester, New York, Brisbane, Toronto, Singapore: John Wiley & Sons. p. 81. ISBN 0471938084.
  18. ^ The Columbia Encyclopedia Sixth Edition, uniformitarianism © 2007 Columbia University Press.
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