This is the online edition of In the Beginning: Compelling Evidence for Creation and the Flood
(7th Edition) by Dr. Walt Brown. The online version of the book is designed to be read online.
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How to Evaluate Theories
To explain scientifically an unobserved event that cannot be repeated, we must first assume the conditions existing before that event. From these assumed starting conditions, we then try to determine what should happen according to the laws of physics. Three criteria should then be used to evaluate the proposed explanation.
Criterion 1: Process. If we can explain all relevant observations better than any other proposed explanation, confidence in our explanation increases. However, if these starting conditions and the operation of physical laws (or known processes) should have produced results that are not present, then confidence in our explanation decreases.
For example, a frequent and intriguing question is, “What caused the extinction of the dinosaurs?” (We will not address that question now, but will use it to show how to evaluate scientific theories attempting to explain unobserved and unrepeatable events.) Some dinosaur extinction theories assume large climatic changes. While many types of climate variation might kill all dinosaurs, we must also (by Criterion 1) look at other consequences of large climatic changes. Flowering plants and many small animals are even more vulnerable to large climatic changes. Because most plants and animals did not become extinct with the dinosaurs, “climatic change” theories for dinosaur extinctions are weakened.
Criterion 2: Parsimony. (Parsimony here means “the use of few assumptions.”) If a few assumptions allow us to explain many things, then confidence in the explanation will be great. Conversely, if many assumptions are used to explain a few observations, or if we must continually add new assumptions or modify our proposed theory as new observations are made, then we should have little confidence in the explanation.
For example, some said that a large asteroid or comet struck the earth and killed all the dinosaurs. Supposedly, the asteroid or comet, containing the rare element iridium, kicked up a worldwide dust cloud that blocked sunlight for several years, reduced photosynthesis on earth, and choked off the dinosaurs’ food chain. Support for this theory comes from layers of clay in Europe, New Zealand, and elsewhere containing iridium. Iridium-rich layers sometimes contain dinosaur fossils and are dated, using evolutionary assumptions, as about 65 million years old.
An asteroid or comet striking the earth might explain the worldwide extinction of the dinosaurs and some iridium layers containing dinosaur fossils. In other words, one starting condition (an impact of a large asteroid or comet) explains two important observations: dinosaur extinctions and iridium layers. This is good.
But there are some hidden assumptions. While most meteorites contain iridium, it has not been detected in asteroids or comets. So, advocates of the impact theory must assume that asteroids or comets have large amounts of iridium (or that meteorites came from comets or asteroids). Other iridium-rich layers have since been discovered too far above and below the layer thought to mark the extinction of the dinosaurs. Further studies have found few iridium-rich layers near known impact craters. (Scientists have recently learned that airborne particles expelled by volcanoes contain considerable iridium and other rare chemical elements that are found in the iridium-rich layers.)32
Also, many marine plants require daily sunlight.33 How could they have survived a global dust cloud that killed the dinosaurs? Each problem might be solved by adding new assumptions. However, by Criterion 2, this reduces our confidence in the theory.
Criterion 3: Prediction. A legitimate theory allows us to predict unusual things we should soon see if we look in the right places and take the right measurements. Verified predictions will greatly increase our confidence in an explanation. Published predictions are the most important test of any scientific theory. Few evolutionists make predictions that can be tested within a thousand years.
What predictions can be made based on the “climatic variation” and “impact” theories? Few, if any, have been made publicly. This does not inspire confidence in these explanations. Rarely do predictions accompany explanations of ancient, unobserved events.
Predictions can be associated with the impact theory. For example, a very large impact crater should be found whose age corresponds to the time of the extinction of the dinosaurs. Fossils of many forms of life should be concentrated near the crater or, at least, in the hemisphere containing the crater. However, dinosaur fossils are uniformly distributed worldwide,34 a point worth remembering.
For several years, no suitable crater could be found.35 Finally, in 1990, an impact site was proposed on Mexico’s Yucatán Peninsula, centered near the village of Chicxulub (CHICK shoo loob). Evolutionists initially dated the site as 40–50 million years before dinosaurs became extinct. No crater shape was visible, but a buried crater was claimed based on slightly circular magnetic and gravitational patterns, much imagination, and the desire to explain dinosaur extinctions. Impact advocates then redated the region and, in effect, predicted that drilling in and around Chicxulub would reveal an iridium layer and a buried impact crater. Later drilling projects found neither.36
Other dinosaur extinction theories have even more problems. Our purpose in this section is not to settle this issue but to show how scientific reasoning should be applied to unobserved, nonreproducible events. Incidentally, another theory on dinosaur extinction will soon become obvious—a theory involving a global flood and the harsh conditions afterward. [For more on dinosaurs, see “What about the Dinosaurs?” on page 348.]
Scientific explanations are never certain or final, and the overused word “prove” is never justified except possibly in mathematics or a court of law. Science is even less certain when dealing with ancient, unrepeatable events, because other starting conditions might work as well or better than the proposed starting conditions. Perhaps we have overlooked a physical consequence or have improperly applied the laws of physics. Certainly we can never consider all the possibilities or have all the data.
So, to try to scientifically understand unobservable, unrepeatable events, we should consider many sets of starting conditions, estimate the consequences of each based on physical laws, and then see how well those consequences meet the above three criteria. Ancient records, such as legends or the Mosaic account in the Bible, do not give scientific support for the truth or falsity of an ancient event. Such records may provide important historical support to people with confidence in a particular ancient record. This, however, is not science. Here in Part II, we will focus on science.