The parallel roads of Glen Roy. Credit: Paul Williams.

The primary goal of scientists is to understand and interpret the natural world.  Scientists like me thrive on figuring out what is physically going on in any given situation.  We do this in part for the raw satisfaction of solving a mystery and gaining new knowledge.  However, we also do it for a very practical reason: understanding how something works usually implies an ability to forecast what it is going to do next.  For example, predicting hurricanes, solar storms, and other natural hazards is a vital component of Earth and space science.

What happens when scientists are confronted with new observations for which there is currently no explanation?  Usually, two or more competing theories are able to offer explanations that seem equally plausible.  Only one of the theories can be correct, but how to choose which one?  Initially, the available evidence is not sufficient to rule out any of the theories.  At this stage in the discovery process, controversy takes centre stage, and heated debates often occur between scientists who have backed opposing theories.  Eventually, new evidence is collected and the incorrect theories are falsified.  The correct theory then becomes part of our stock of accepted knowledge.  In essence, this is how progress is made in science.

Telling the history of the discovery process is not always how science is taught in schools and universities.  It is easier and faster just to communicate the end result, rather than to dwell on the controversial arguments that took place and the mistakes that were made.  Therefore, the stock of accepted knowledge is often passed on to students as if it had simply been handed down from some great authority in the past.  But to gloss over the history of the discovery process is an oversimplification.  I believe it is vital for all science educators – not just those who specialize in teaching the history of science – to acknowledge that the facts we know today were only uncovered after a great deal of research and debate.

Some of the greatest scientists in history have backed the wrong theory, often in spectacular fashion. Even the great Charles Darwin was not immune.  See the three parallel striations about halfway down the photograph?  They are the Parallel Roads of Glen Roy, a glacial leftover in the Scottish Highlands that once baffled scientists.  In the middle of the nineteenth century, Charles Darwin and Louis Agassiz published competing theories for their origins.  As explored in the short film, Darwin’s theory turned out to be incorrect, to his eventual shame and regret.  But he remained philosophical, writing:

“False facts are highly injurious to the progress of science, for they often endure long; but false views, if supported by some evidence, do little harm, for everyone takes a salutary pleasure in proving their falseness; and when this is done, one path towards error is closed and the road to truth is often at the same time opened.”

YouTube video
A short film exploring the role of controversy in science.  Credit: The Royal Society.

The advent of scientific publishing greatly accelerated the resolution of disagreements like the one between Darwin and Agassiz.  Up until 1665, when the world’s first science journals were launched, scientists could not and did not publish their findings.  When new evidence was collected, it was shared only among small circles of scientists in private letters.  The lack of scrutiny from other scientists – and the public – prolonged the resolution of scientific disagreements.  Fortunately, progress in Earth and space science is much faster today, thanks in part to the journals published by the American Geophysical Union and other societies.

—Paul D. Williams, Editor, Geophysical Research Letters; email:


Williams, P. D. (2016), Controversy: A crucial ingredient for scientific progress, Eos, 97, Published on 13 June 2016.

Text © 2016. The authors. CC BY-NC-ND 3.0
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