8 Can explanations become settled science?

How a concept, once an hypothesis, can become an irrefutable fact

This is the ninth post in this series. If you haven’t read the Introduction titled The Myth of Scientific Uncertainty, and posts numbered 1-7, you may want to do those first.

We have shown that there is a part of scientific knowledge that we can be sure of, i.e., the verified laws applied within their tested limits. We have also seen that the explanations of these laws are analogies that may be revised and generally work on only one level of complexity. So one might assume that no explanations are completely settled as representing reality. That could be going too far. There are some explanations that, at their level, seem to be final.

The hypothesis of a spherical earth based on the observation of ships disappearing over the horizon would be an early example. There are now so many confirmations of the shape of our planet, including pictures from space, it is no longer vulnerable to reasonable doubt.

When we had competing explanations (geocentric and heliocentric) of planetary motion, neither one was certain. Then, Galileo’s observations supported the heliocentric model enhancing its credibility. Since that time, there have been so many incontrovertible observations and confirmations that the conclusion that the earth is among the planets orbiting the sun is no longer in doubt. This is an example of something that began as an explanation but is now ‘settled science.’ Though we should use the word ‘truth’ very carefully with respect to scientific knowledge, it does not seem a stretch to say it is true that the planets, including the earth, orbit the sun.

Nor is it questionable that water is composed of hydrogen and oxygen atoms in a ratio of two to one.

The concept of the chemical elements and their masses also began as conjectures to explain various substances and behaviors but have become verified realities. Again, it is important to note that the explanation for chemical composition centered around the elements and interatomic bonds is ‘settled’ on the level associated with those entities. There is still so much to learn about the fundamental nature of matter.

A more recent example is that of the movement of tectonic plates on the earth’s surface. Alfred Wegener introduced the concept of continental drift in 1912. This was his most significant scientific contribution, so it may be surprising that his doctorate was in astronomy with strong interests in meteorology and climatology. Perhaps it was a meteorologists’ extensive familiarity with maps that sparked his curiosity about how the shapes of the continents, if abutted, fit together so well. From this, and the observation of mid-ocean trenches and ridges, he posited that the continents had drifted to their present dispersion from a contiguous configuration now called Pangea.

But authorities in the field rejected his idea. As the Wikipedia article points out and as we saw in the previous section, “… it didn’t help that Wegener was not a geologist.” It also did not help that most geologists believed in an idea called isostasy that would prevent continental movement. But evidence of continental drift mounted.

Now called plate tectonics, the concept of continental drift is no longer an explanation for the remarkable picture-puzzle fit of the continental shapes, it is settled science. Geologists have measured the rates of movement in millimeters per year or, more prosaically, at the rate of growth of our fingernails.

It is interesting to consider at what point an explanation becomes settled science. The helical structure of DNA was at one time a conjecture but is now no longer in question. A concept becomes increasingly certain with the accumulation of confirming data. We have learned which nucleic acids make up its base pairs and how they form the overall helical structure. It has been confirmed, initially by X-ray analysis, but more recently by atomic force microscopy. Several variants have been found and been characterized. As we empirically reveal more details, the initial concept becomes more settled, or as I put it, settled in fact. But, until empirically verified in incontrovertible ways, an explanation, no matter how sensible, is provisional.

This empirical confirmation is essential to the firm establishment of an explanation. An explanation can appear to be settled science by its widespread acceptance and repetition. Current examples are the cosmological concepts of dark matter and dark energy. There are many reasons to believe they may exist since their postulation explains the acceleration in the rate of expansion of the universe and resolves observations of stellar velocities inconsistent with the laws of gravity. And many publications assume that their reality has been established. But the absence of reasonable alternative explanations is not the same as empirical confirmation. That’s why we are making such efforts to find the source of the “missing’ mass and energy. Until then, they are just postulates.

In the next post, we will address the third pillar of scientific uncertainty which is: Our ‘simple’ laws do not apply in the real world where multiple factors can affect the outcome. Their predictions are therefore flawed.

Please spread the word that there are some things we know for sure.

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