Science knows…. As well as we can know anything

Historically large and devastating wildfires burning in the western U.S. are delivering aerosols across the United States. Image by the NASA Earth Observatory (public domain).

Historically large and devastating wildfires burning in the western U.S. are delivering aerosols across the United States. Image by the NASA Earth Observatory (public domain).

by Dr. Warren D. Allmon, Director

Last updated September 15, 2020

In a September 14 meeting with President Trump, Wade Crowfoot, California’s secretary for natural resources said to the President: “If we ignore that science and sort of put our head in the sand and think it’s all about vegetation management, we’re not going to succeed together protecting Californians.”

The President responded: “It’ll start getting cooler. You just watch.”

“I wish science agreed with you,” Mr. Crowfoot replied.

“Well, I don’t think science knows, actually,” Mr. Trump said.

“Trump Clashes with California Officials on Climate Change: ‘I Don’t Think Science Knows’” (Bloomberg QuickTake News; Youtube).

The word “know” can be problematic in science, because it is frequently used in everyday speech to mean “have absolute certainty” about something. Absolute certainty is not what science is about. Science is not about certain knowledge, but – in biologist John Moore’s excellent phrase – “a way of knowing.” Science makes observations about the material world and uses the rules of logic to test hypotheses – ideas – about how that world is. The hypotheses with the most support are provisionally accepted, meaning they are considered to be adequate until sufficient contrary evidence comes along. Some scientific ideas have so much evidence in their support that they are treated as “effectively true” or as “scientific facts” – what paleontologist Stephen J. Gould called ideas that are “confirmed to such a degree that it would be perverse to withhold provisional assent”.

Is it possible that human activity is not the primary cause of current global warming and other manifestations of climate change? Yes, but it is exceedingly unlikely. It is similarly possible that the Sun is not at the center of the solar system or that a virus does not cause COVID-19, but these hypotheses are supported by essentially all available evidence, and are durable understandings that are profoundly useful in helping us make predictions about what will happen and decide relevant action.

Clarifying what “know” means is not a version of the Clintonian “It depends upon what the meaning of the word ‘is’ is.” It is vital to everyone’s understanding of what science is and how it works. Science is demonstrably the most effective way humans have ever developed to understand, predict, and manipulate the physical world. No other approach even comes close in its practical effectiveness. If you don’t believe this, consider it the next time you go to the doctor, watch a weather report, or fly in an airplane. Science as a method works. But sometimes it tells us things that are uncomfortable and difficult to accept – “inconvenient truths.” Even, maybe especially, in such cases, we must be prepared to follow where it leads.

Human-caused climate change was first raised as a serious scientific idea more than a century ago, and the evidence in its favor has only increased – not decreased – in the time since. Although it is still the case that individual storms or wildfires or icebergs cannot with high confidence be attributed to human activity, the overall patterns of these phenomena are now so clearly consistent with what would be expected of human-caused increases in greenhouse gasses that it would be perverse to withhold our provisional assent. Scientific conclusions are and must always be open to contrary evidence and argument, but at a certain point, we treat many scientific conclusions as though they are, for all in intents and purposes, true. In this sense, we “know” that wildfires are more frequent and widespread, that hurricanes are stronger, and that polar ice is melting more quickly because of human activity.

When politicians say “science doesn’t know” about a topic that science does in fact “know” as well as anything about the physical world can be known, they are not telling the truth. Letting this happen endangers both science and human welfare.