|Barred spiral galaxy NGC1672 [Courtesy NASA]
Are evolution and old-earth geology built on a "uniformitarian" assumption?
David H. Bailey
Updated 31 March 2019 (c) 2019
In their literature, creationists and even an occasional intelligent design writer often claim that modern science in general, and evolution and old-earth geology in particular, are built on the shaky and unjustified foundation of a "uniformitarian" assumption. For example, creationist Henry M. Morris wrote "The evolution model is associated primarily with uniformitarianism, but evidence of catastrophism makes the uniformitarian assumption untenable [Morris2000, pg. 91-100]. Similarly, R. Albert Mohler, President of the Southern Baptist Theological Seminary, declared that "There is absolutely no reason that a Christian theologian should accept the uniformitarian assumptions of evolution." [Mohler2011].
The term "uniformitarianism" actually arose in the 19th century, when Charles Lyell published his multi-volume treatise Principles of Geology. The subtitle of this work was "An attempt to explain the former changes of the Earth's surface by reference to causes now in operation." The terms "uniformitarianism" and "catastrophism" were actually coined by William Whewell in a review of Lyell's book.
However, modern geology and biology have long since moved beyond these simple concepts, recognizing that while the Earth's history is a slow process of gradual change, this process has been punctuated by periodic natural catastrophic events. For example, in the late twentieth century, J. Harlan Bretz demonstrated that the Scablands in eastern Washington state were formed from a large flood, which in turn resulted when a glacial lake broke through an ice dam. Similarly, in 1980, Luis Alvarez proposed that an asteroid impact was responsible for the extinction of dinosaurs 65 million years ago. Modern scientists are more apt to use the term "actualism" to refer to this combination of slow processes and catastrophic events [Isaak2007, pg. 161].
In articles on geologic ages (see
we presented a chart with the various geologic eras and their ages. In the articles on radiometric dating (see
and radiocarbon dating (see
we briefly described how these dates are calculated using radiometric dating techniques. As we pointed out in those articles, these ages are based on known rates of radioactivity, a phenomenon that is rooted in fundamental laws of physics and follows simple mathematical formulas. In a related article on the reliability of radiometric dating (see
we discussed in detail how these methods have been tested and refined over the years, and why they deserve the trust that scientists place in them.
Rates of radioactivity
One key question that arises in this context is how can scientists assume that rates of radioactivity have been constant over the great time spans involved. In fact, this assumption has been tested at some length. Numerous experiments have been conducted to detect any change in radioactivity as a result of chemical activity, exceedingly high heat, pressure, or magnetic field. None of these experiments have detected any significant deviation for any isotope used in geologic dating [Dalrymple1991, pg. 86-89; Dalrymple2004, pg. 58-60].
Constants of physics
Scientists have also performed very exacting experiments to detect any change in the constants or laws of physics over time, but various lines of evidence indicate that these laws have been in force, essentially the same as we observe them today, over the multi-billion-year age of the universe. For example, the motion of stars in distant star clusters appears to follow the same laws of gravitation that we see in effect in our solar system and, for that matter, when apples fall from trees. Also, detailed studies of light coming to Earth from distant stars (which, in many cases, emanated millions or even billions of years ago) reflects the same patterns of atomic spectra, based in the laws of quantum mechanics, that we see today in earth-bound experiments, confirming that these laws are in effect over wide ranges of time and space. For example, in supernova events that we observe in telescopes today, most of which occurred many millions of years ago, the patterns of light and radiation are completely consistent with the laws of quantum mechanics and the half-lives of radioactive isotopes that we measure in earth-bound laboratories today. For additional details, see Time machine.
As another item of evidence, researchers studying a natural nuclear reactor in Africa have concluded that the fine structure constant ("alpha"), which is a key parameter in analysis of radioactive decay, has not changed measurably in hundreds of millions of years [Barrow2007, pg. 124-128].
Perhaps the most dramatic confirmation that the constants of physics have not changed significantly over cosmic time was announced in March 2016. Researchers in the Netherlands and Australia announced that by careful analysis of astronomical spectra in a galaxies up to 12.4 billion light-years away (which means that the reactions they studied occurred 12.4 billion years ago), they were able to conclude that the proton-to-electron mass ratio (approximately 1836.1526) has not changed by more than 0.0005 percent from its present value over this period of time [Srinivasan2016].
Thus scientists are on very solid ground in asserting that rates of radioactivity have been constant over geologic time, and that the consensus dates of the geologic ages are reliable.
The young-earth creationist worldview would not only require that rates of radioactivity have changed measurably over the eons, but in fact that they have changed enormously -- by factors of a million or more. Needless to say, such enormous variations are utterly ruled out by all available data. In light of this data, the only reasonable recourse available to these creationists is to assert that prior to a few thousand years ago, the Earth and universe were governed by utterly different laws, but that about 4000 BCE God altered the Earth and universe to have an "appearance of age." But this "solution" is not a testable, scientific concept, and in addition presents huge theological problems as well -- see
In addition to the references mentioned above, useful information is available in online articles by Roger Wiens [Wiens2002] and Brent Dalrymple [Dalrymple2006]. For additional discussion, see