User:Christian Skeptic/Uniformitarianism (science) rewrite

Uniformitarianism, in the philosophy of science, is the assumption that says that the same natural processes that operate in the universe now, have always operated on the universe in the past, and at the same rates; and that the same laws of physics apply everywhere in the universe.

“ The present is the key to the past. ”

Uniformitarianism is defined in the Glossary of Geology:

“The fundamental principle or doctrine that geologic processes and natural laws now operating to modify the Earth's crust have acted in the same regular manner and with essentially the same intensity throughout geologic time, and that past geologic events can be explained by phenomena and forces observable today.”

The concept of uniformity in geological processes can be traced back to the Persian geologist, Avicenna (Ibn Sina), in The Book of Healing (1027). Uniformitarianism was later 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. The term uniformitarianism was coined in 1832 by William Whewell, who also coined the term catastrophism for the preceding idea that the Earth had been created through supernatural means and had then been shaped by a series of catastrophic events caused by forces which no longer prevailed.

Uniformitarianism is one of the most basic principles of modern geology, the observation that fundamentally the same geological processes that operate today also operated in the distant past. Less well appreciated is its importance as an element in astronomy, in that it also assumes infinitely deep time for the entire universe.

It exists in contrast with catastrophism, which states that Earth surface features originated suddenly in the past, by geological processes radically different from those currently occurring. Note, however, that many "catastrophic" events are perfectly compatible with uniformitarianism. For example, 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.

Uniformitarianism is a generalisation of the principle of actualism, which states that present day-processes (astronomical, geological, paleontological,...) can be used to interpret past patterns. The principle of actualism is the cornerstone of paleoecology.

A uniformitarian is one who believes in the principles, or any number of aspects and/or assumptions of the philosophy of uniformitarianism.

History

The concept of uniformitarianism 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 recognized that mountains were formed after a long sequence of events that predate human existence. 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."

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

After The Book of Healing was translated into Latin in the 12th century, a few other scientists also reasoned in uniformitarian terms, but the theory was not accepted until the late 18th century. The uniformitarian explanations for the formation of sedimentary rock and an understanding of the immense stretch of geological time or 'Deep time' was promoted by the 18th-century geologist James Hutton, a pioneer of the principle, in "Theory of the Earth", which was later expanded upon and popularised by Charles Lyell in his three-volume series "Principles of Geology" first published 1830-1833. Charles Darwin took Lyell's books on board the ship HMS Beagle. During that voyage, Lyell's works informed Darwin's thinking about slow biological change known as gradualism.

In the 18th and 19th centuries, the debate between the catastrophism and uniformitarinism theories was intense, because uniformitarianism seemed hard to reconcile with the prevailing religious beliefs of the time.

Lyellian Uniformitarianism

Under the term uniformity, Lyell conflated two different types of propositions: a pair of philosophical axioms (required for science to work) and a pair of hypotheses. The axioms are universally acclaimed by scientists, and embraced by all geologists. However, the hypotheses were and still are controversial and accepted by few.

Unfalsifiable axioms

• Uniformity of law
• Uniformity of process

Falsifiable hypotheses

• Uniformity of rate
• Uniformity of state

Unfalsifiable axioms

As axioms, the first two propositions listed above cannot be tested or falsified by science. You can't 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 round, before you can proceed as a scientist, you must 1) assume that nature's laws are invariant and 2) you choose to exhaust familiar causes before inventing any unknown mechanisms. Then you go to the outcrop of rock.

Uniformity of law

“ Natural laws are constant across space and time. ”

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.”

In essence, we must assume the constancy of natural laws in our study of the past, because if we do not, then we cannot meaningfully study the past.

The necessity of assuming uniformity of law in order to make 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 the 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.

Since there is no human who understands everything there is to know about nature and it laws, we need to allow for the possibility that nature’s laws may not be only what we experience and imagine them to be. And so, we may not be able to meaningfully study the past. However, with recognition of this concession, we assume the invariance of nature until evidence forces a change in paradigm.

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.

”

We should try to explain the past by causes now in operation without inventing extra, fancy, or unknown causes, however plausible in logic, if available processes suffice. This is known as the scientific principle of parsimony or Occam's razor. Just as one should not invent unobservable causes when observable ones are sufficient, one should not neglect unobservable causes when observable ones are insufficient.

Space and Time

It is impossible to learn anything about the cosmos unless the axioms of uniformity of law and process are extended to ‘out there’ across space.

Falsifiable hypotheses

Lyell’s other two uniformity propositions are radically different in status. Rather than being axioms they are hypotheses that may be judged true or false on empirical grounds through scientific observation and repeated experimental data.

Uniformity of rate (or "Gradualism")

“ Change is typically slow, steady, and gradual. ”

Mountain ranges or Grand Canyons are built by accumulation of near 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.

Modern Geology rejects strict uniformity of rate

By force of popularity, uniformity of rate has persisted to our present day. For more than a century, Lyell’s rhetoric conflating axiom with hypotheses has descended in unmodified form. Many geologists have been stifled by the belief that proper methodology includes an a priori commitment to gradual change, and by a preference for explaining large-scale phenomena as the concatenation of innumerable tiny changes. 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.

Modern geologists do not apply uniformitarianism in the same fashion as Lyell and his contemporary scientists. Twentieth-century geologists question if uniformity of process should also require that the rate of processes be uniform through time and limited to values measured during the history of geologic study. Geologic studies of active processes have been ongoing for less than 4 ten-millions of Earth history which is insufficient for observing episodic, rare and extreme events. It is possible for processes to have been active at different rates in the past that humans have not witnessed. Evolutionary Geologist Derek Ager echos with "Is the Present a long enough key to penetrate the deep lock of the past?"

Uniformity of state ( or "Nonprogressionism")

“ Change is evenly distributed throughout space and time. ”

The history of our earth follows 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. So, we can use its current order (not only its laws and rates of change) to infer its past. The earth had no early period of more vigorous convulsion.

Lyell rejects uniformity of state

Charles Lyell had a 'steady state' view of the Earth and its life. He conceded that many species had become extinct, but could not accept the idea that the Earth was once wholly inhabited by very simple forms of life. But, late in his career, accumulating evidence that many fossils are found only in some parts of the geologic record forced him, reluctantly, to accept evolution's progression in life's history. He finally surrendered his commitment to nonprogressionism. Evolution served Lyell as touchstone for this minimal retreat. With evolution, he could still hold firm to uniformity of rate, especially with Darwin's idea that nature does not make leaps. He could continue to embrace uniformity of law, for evolution makes use of known general Law. And actualism remained intact, for Darwin insisted that small scale changes of ordinary genetic variation were, by logical, but unprovable, extension, the stuff of all evolutionary change.

The impact of uniformitarianism

Lyell defended uniformity of rate and state not by logic but with rhetoric — he conflated these controversial hypotheses about the nature of things with the philosophical axiom that all scientists accept, thereby attempting to secure an a priori status for his hypotheses. He argued that the claims of catastrophism were unintelligible in principle because all scientists accept the uniformities of law and process, tacitly including his concepts of gradualism and nonprogressionism. It was his rhetoric as a lawyer, rather than the validity of his claims, that won the controversy with catastrophists of his day. And it has had a deleterious effect on geology ever since.

Stephen J. Gould has said:

“ Lyell's gradualism has acted as a set of blinders, channeling hypotheses in one direction among a wide range of plausible alternatives. Its restrictive effects have been particularly severe for those geologists who succumb to Lyell's rhetorical device and believe that gradual change is preferable (or even required) a priori, because different meanings of uniformity are necessary postulates of method. Again and again in the history of geology after Lyell, we note reasonable hypotheses of catastrophic change, rejected out of hand by a false logic that brands them unscientific in principle. ”

According to Richard Hugget, the diluvialists have had a very raw deal ever since Lyell insinuated uniformitarianism into geology. The views of the past masters of Earth surface history have been handed down to us in a very partial manner. If any reference is made at all concerning the works of the diluvialists in modern textbooks, they are usually scathing and erroneous.

Uniformitarianism today

As shown above uniformitarianism has now been trimmed down to Lyell’s first two presuppositions – Uniformity of Law and Process. And these are embraced by all practicing geologists. The more recent tendency has been to admit the existence in earth history of periods when such activity was accelerated and intensified. In general however, just as Bates and Jackson state above, evolutionary geologists tend to favor gradualism, allowing only for occasional and rare catastrophes, which may, but are not likely to, involve the entire globe.