1. The trace that remains

The still-valid part of disproved theories

This is the second post in this series. If you haven’t read the introduction titled The Myth of Scientific Uncertainty, you may want to do that first. See it at https://chrisenke.substack.com.

1 The trace that remains

The first pillar of scientific uncertainty is the number of missteps science has had along the way. An early example is the notion of a geocentric solar system. But misconceptions continue throughout history. Lavoisier proposed that the transfer of heat is due to the motion of a caloric fluid, Becher explained combustion as the release of a substance called phlogiston, Boyle and Huygens supported the notion that light waves would require a medium they called the luminous aether, and Einstein believed, until astronomers revealed the red-shift in absorption and emission spectra from distant galaxies, that the universe was static.

In each of the above cases, later data made those explanations untenable. Given that track record, one would naturally suspect that a contrary observation might undo any of our current theories.

But that conclusion has long bothered scientists and philosophers who believed that at least some knowledge must be certain. If a theory has worked and made accurate predictions, how can it be completely wrong? In the 19^th century, Henri Poincaré wrote on what he called “the trace that remains” of disproved theories. He looked at them and found the part that remains valid is within the laws^[1], (statements of relationships) such as the Newton’s gravitational equation F = Gm₁m₂/d², or water freezes at 0º C. He believed that no matter what we learned about the nature of phenomena (the nature of gravity or the structure of water), experimentally confirmed laws would continue to work. In other words, part of a theory can be revised or disproved while another part remains valid.

Reading Poincaré’s writings on this point was encouraging. Though not a complete answer, I began to see that later theories would have to accommodate the confirmed data on which the earlier theory was based. And further, that many equations based on those data would also still work, even if replaced by better versions. For example, the geocentric equations for planetary position still work as well as they did when derived.

Besides giving us a clue on where to look for certainty, Poincaré’s thoughts imply another essential aspect of scientific knowledge which is that a scientific theory or concept has two distinct elements. One of them is our confirmed observations of how factors are related, i.e., our laws. The other is our explanation of the laws—why they work that way^[2]. The equations and relationships are the functional part of a theory, enabling the prediction of outcomes. The explanation, the part that may change as we learn more, links with other explanations in the fabric of scientific knowledge.

Scientific realists including Worrall^[3], Putnam^[4], and Ladyman^[5], have extended Poincaré’s thoughts. They argue that the success of science would be a miracle were there not some aspects that represent reality. In fact, one definition of the word ‘miracle’ is “an event that is inexplicable by natural or scientific laws.

Imagine this: You have just opened the latest issue of Science magazine to read that studies have shown that electrical conduction can occur without the physical movement of charge carriers, thus challenging a premise of Ohm’s theory of conduction. If confirmed, all electrical and electronic devices based on Ohm’s law may become non-functional. Meanwhile, caution is advised while using anything electronic.

You know that the above scenario would not happen because a different understanding of the mechanism of electrical conduction will not change the observations Ohm’s Law is based on nor the reliability of devices designed using it. So there are things we know for sure and can count on to remain valid even after the original premise or explanation part of the theory changes. As we’ve said, these certainties will be found among the laws scientific research and technological applications are based on. But this does not resolve the problems of potential exceptions and the complexities of the what and the why of scientific theories.

We’ll look into that next.

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[1] H. Poincaré, “The Value of Science” in The Foundations of Science. (1913) (Academia Renascens, 2021) p.352.

[2] H. Margenau, The Nature of Physical Reality, a Philosophy of Modern Physics. (McGraw-Hill, New York, reprinted Ox Bow Press, Woodbridge, 1977) p. 448.

[3] J. Worrall, Miracles, Pessimism and Scientific Realism, PhilArchive, https://philarchive.org/rec/WORMPA

[4] H. Putnam, Mathematics, Matter and Method (: Cambridge University Press, Cambridge 1975) p.73.

[5] J. Ladyman, What is Structural Realism? Studies in History and Philosophy of Science, 29: pp. 409–424.