Uniformitarianism

Hutton discordance in Jedburgh.
Above: illustration of John Clerk of Eldin (1787).
Below: Photography of 2003.

In the philosophy of science, uniformitarianism, also known as the Uniformity doctrine, is the assumption that the same natural laws and processes that operate in Current scientific observations have always operated in the universe in the past and apply throughout the universe. It refers to invariance in the metaphysical principles that underpin science, such as the constancy of cause and effect across space-time., but it has also been used to describe the spatiotemporal invariance of physical laws. Although an untestable postulate that cannot be verified using the scientific method, uniformitarianism has been a key first principle of virtually every field of science.

In geology, uniformitarianism has included the gradualist concept that "the present is the key to the past" and that geological events occur at the same rate as they always have, although many modern geologists no longer hold to strict gradualism. Coined by William Whewell, it was originally proposed in contrast to catastrophism by British naturalists in the late 18th century, beginning with the work of geologist James Hutton in his many books, including Theory of the Earth. Hutton's work was later refined by scientist John Playfair and popularized by geologist Charles Lyell, Principles of Geology in 1830. Today, Earth's history is considered to have been a slow and gradual process, punctuated by occasional catastrophic natural events.

History

18th century

Acantied in the east of Siccar Point in Berwickshire, which shows the almost horizontal layers of red sandstone on vertically tilted gravel.

Earlier conceptions^[which?] probably had little influence on the geological explanations for the formation of the Earth that appeared in Europe in the XVIII. Abraham Gottlob Werner (1749-1817) proposed Neptunism, where the strata represented precipitated deposits from receding seas on primordial rocks, such as granite. In 1785, James Hutton proposed a self-contained opposite infinite cycle based on natural history rather than the Biblical account.

The solid parts of the current earth seem, in general, to have been composed of sea productions and other materials similar to those that are now on the shores. That is why we find reason to conclude:

1.o, that the land in which we rest is not simple and original, but is a composition, and formed by the operation of second causes.

2.o, that before the present land was made, a world composed of sea and land had subsisted, where the tides and currents were, with such operations at the bottom of the sea as they now take place. And,

Finally, while the current earth was forming at the bottom of the ocean, the previous land kept plants and animals; at least the sea was then inhabited by animals, in a manner similar to the current one.

Therefore, it leads us to the conclusion that most of our land, if not all, was produced by natural operations on this planet; but that to make this land a permanent body, resisting the operations of the waters, two things had been required;

1.o, the consolidation of masses formed by collections of loose or incoherent materials;

2.o, the elevation of these consolidated masses from the bottom of the sea, the place where they were gathered, to the places where they now remain above the ocean level.

Hutton then looked for evidence to support his idea that there must have been repeated cycles, each involving deposition on the seafloor, uplift with tilting and erosion, and then underwater movement again for them to be deposited. more layers. At Glen Tilt in the Cairngorm Mountains, he found metamorphic schists penetrating the granite, in a way that told him that the presumed primordial rock had melted after the strata had formed. He had read about the angular unconformities interpreted by the Neptunists, and found an unconformity at Jedburgh where layers of greywacke in the lower levels of the cliff face had been tilted almost vertically before eroding to form a level plane, which now lay under horizontal layers of Old Red Sandstone. (old red sandstone). In the spring of 1788 he took a boating trip along the Berwickshire coast with John Playfair and the geologist Sir James Hall, and found a radical unconformity showing the same sequence at Siccar Point. Playfair later recalled that "the mind seemed to grow dizzy looking so far into the abyss of time", and Hutton concluded a paper in 1788 which he presented at the Royal Society of Edinburgh, which was later rewritten as a book, with the phrase "we find no vestige of a beginning, no prospect of an end".

Both Playfair and Hall wrote their own books on the theory, and for decades, a robust debate continued between Hutton's supporters and Neptunists. The paleontological work of Georges Cuvier in the 1790s, which established the reality of extinction, is explained by local catastrophes, after which other fixed species repopulated the affected areas. In Britain, geologists adapted this idea into the flood theory which proposed the repeated annihilation and creation of new fixed species adapted to a changed environment, initially identifying the most recent catastrophe as the Biblical flood.

19th century

Charles Lyell at the meeting of the British Association in Glasgow in 1840

From 1830 to 1833, Charles Lyell's Principles of Geology were published in several volumes. The subtitle of the work was "An attempt to explain the former changes of the Earth's surface by reference to causes now in operation". are now operating]. He drew his explanations from his field studies conducted directly before he began work on the founding text of geology and developed Hutton's idea that the Earth was formed entirely by slow-moving forces that are still at work today, acting over a very long period of time. William Whewell coined the terms "uniformitarianism" for this idea and "catastrophism" for the opposite view in a review of Lyell's book. The work Principles of Geology was the most influential geological work in the mid-19th century.

Inorganic Earth History Systems

Geoscientists support various systems in Earth history, the nature of which is based on a certain mix of preferred views of process, control, speed, and state. Because geologists and geomorphologists tend to take opposing views of process, rate, and state in the inorganic world, there are eight different belief systems in the development of the earth sphere. All geoscientists uphold the principle of uniformity of law. Most, but not all, are guided by the principle of simplicity. All make definitive claims about rate quality and status in the inorganic realm.

Lyell's Uniformitarianism

According to Reijer Hooykaas (1963), Lyell's uniformitarianism is a family of four related propositions, not a single idea:

• Uniformity of law: the laws of nature are constant in time and space.
• Uniformity of methodology: the appropriate hypotheses to explain the geological past are those that have analogy today.
• Class uniformity: the past and present causes are all of the same type, have the same energy and produce the same effects.
• Grade uniformity: geological circumstances have remained the same in time.

None of these connotations require the others, and not all are equally inferred by uniformitarians.

Gould explained Lyell's propositions in Time's Arrow, Time's Cycle (1987), stating that Lyell combined two different kinds of propositions: a pair of methodological assumptions with a couple of substantive hypotheses. The four together form Lyell's uniformitarianism. .

Methodological assumptions

Most scientists and geologists accept that the following two methodological assumptions are true. Gould claims that these philosophical propositions must be assumed before one can continue as a scientist doing science. “You cannot go to a rock outcrop and observe the constancy of the laws of nature or the operation of unknown processes. It works backwards." You first assume these propositions and "then you go to the upwelling".

• Uniformity of law in time and space: natural laws are constant in space and time.

The axiom of uniformity of the law is necessary for scientists to extrapolate (through inductive inference) in the unobservable past. The constancy of natural laws must be assumed in the study of the past; otherwise it cannot be studied significantly.

• Uniformity of the process in time and space: natural processes are constant in time and space.

Although similar to the uniformity of the law, this second assumption a priori, shared by the vast majority of scientists, deals with geological causes, not physical-chemical laws. The past should be explained by processes that currently operate in time and space rather than inventing extra esoteric or unknown processes without a good reason, also known as parsimonia or Navaja de Occam.

Substantive hypotheses

The substantive hypotheses were controversial and, in some cases, accepted by few. These hypotheses are judged true or false in empirical terms through scientific observation and repeated experimental data. This is in contrast to the two previous philosophical assumptions that come before one can do science and therefore cannot be proven or falsified by science.

• Uniformity of the rate in time and space: change is usually slow, steady and gradual.

Uniformity of rate (or gradualism) is what most people (including geologists) think when they hear the word "uniformitarianism", which confuses this hypothesis with the whole definition. In 1990, Lemon, in his textbook of stratigraphy, stated that “the uniformity vision of Earth’s history maintained that all geological processes are produced continuously and at a very slow pace”.

Gould explained Hutton's opinion about the uniformity of the rate; mountain chains or large cannons are built by the accumulation of almost insensitive changes that accumulate over time. Some important events, such as floods, earthquakes and eruptions, occur. But those catastrophes are strictly local. They did not occur in the past, nor will they occur in the future, with a greater frequency or extension than they currently show. In particular, the whole earth is never convulsed at once.

• Uniformity of state in time and space: change is distributed evenly in space and time.

The uniformity of the state hypothesis implies that throughout the history of our earth there is no progress in any inexorable direction. The planet has almost always been seen and behaved as it does now. Change is continuous, but it does not lead anywhere. The earth is in balance: a dynamic stationary state.

20th century

Stephen Jay Gould's first scientific paper, Is uniformitarianism necessary? (1965), reduced these four assumptions to two. the spatial and temporal invariance of natural laws, since it was no longer a matter of debate. He rejected the third (rate uniformity) as an unwarranted limitation on scientific inquiry, since it restricts past rates and geological conditions to those of the present. Therefore, Lyellian uniformitarianism was unnecessary.

Uniformitarianism was proposed in contrast to catastrophizing, which states that the distant past "consisted of epochs of paroxysmal and catastrophic action interposed between periods of comparative tranquility".:small-caps;text-transform:lowercase">XIX and early XX century, most of geologists took this interpretation to mean that catastrophic events are not important in geological time. An example of this was the debate over the formation of the Channeled Scablands due to the catastrophic Missoula glacial flood. An important result of this and other debates 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. Derek Ager has pointed out that «geologists do not deny uniformitarianism in its strict sense, that is, of interpreting the past by means of the processes that are observed at the present time, as long as we remember that the periodic catastrophe is one of those processes. These periodic catastrophes cause more to show up in the stratigraphic record than we have hitherto assumed." Even Charles Lyell thought that ordinary geological processes would cause Niagara Falls to move upstream toward Lake Erie within 10,000 years, causing catastrophic flooding across much of North America.

Modern geologists do not apply uniformitarianism in the same way as Lyell. They wonder if the rates of processes were uniform over time and only values measured during the history of geology would be accepted. The present may not be a long enough key to penetrate the deep lock of the past. The processes Geologics may have been active at different rates in the past that humans have not observed. By force of popularity, the uniformity of the rate has persisted to this day. For more than a century, Lyell's rhetoric combining the axiom with the hypotheses has gone down without modification. Many geologists have been stifled by the belief that the proper methodology includes an a priori commitment to gradual change, and by a preference to explain large-scale phenomena as the concatenation of innumerable small changes."

The current consensus is that Earth's history is a slow, gradual process punctuated by occasional natural catastrophic events that have affected the Earth and its inhabitants. In practice, it boils down to the combination, or mixture, of Lyell to simply the two philosophical assumptions. This is also known as the principle of geological actualism, which states that all past geological actions were like all present geological actions. The principle of actualism is the cornerstone of paleoecology.^{[citation needed]}