I wrote about politicians talking science for a blog hosted by Oxford University Press in June 2015. In that posting, I focused on statements by Jeb Bush and Ted Cruz illustrating their misunderstanding of the scientific consensus about climate change. This new posting was inspired by Rand Paul’s answer to a question about climate change in the November 11th debate among Republican presidential candidates and illustrates a valuable aid to critical thinking called argument mapping.
In an interview a year ago, Paul expressed some support for regulating carbon dioxide emissions, but in the recent debate he stated that his first action as president would be to repeal President Obama’s regulations to control emissions that contribute to climate change. Paul argued for an “all of the above” energy policy, including not only sustainable sources like solar power but also traditional fuels like coal that release greenhouse gases contributing to climate change. In making this argument, Paul said: “The planet’s 4.5 billion years old. We’ve been through geologic age after geologic age. We’ve had times when the temperature’s been warmer, we’ve had times when the temperature’s been colder. We’ve had times when the carbon in the atmosphere’s been higher.” Unlike some candidates, Paul accepts the fact that humans influence climate, but, like all climatologists, he believes that “nature also has a role”.
What kind of argument is Paul making here? How does his plan to repeal emissions controls in support of an all of the above energy policy relate to his riff about the climate history of Earth? He doesn’t make an explicit connection between energy policy and climatology, but his main claim seems to be that we can continue to burn fossil fuels without adverse effects because current carbon levels in the atmosphere and current global temperatures are within the range of values that Earth has experienced in the past. Here is a diagram that illustrates his argument:
This diagram is called an argument map. The sentence in the top box is Paul’s main contention; the two sentences in the green box below are linked premises that explain his contention by acknowledging that burning fossil fuels causes climate change but suggesting that we can do so safely. The two sentences in the lowest box are the crux of his argument in support of his contention. The premise on the left in this lowest box is what Paul said about carbon in the atmosphere and is a true statement of what climatologists have discovered from various kinds of evidence. The co-premise on the right is an unstated assumption of Paul’s argument that links this climatological record to Paul’s claim about the safety of continuing to burn fossil fuels.
Although the main premise of Paul’s argument is true, the co-premise is irrelevant because humans have never existed with atmospheric carbon dioxide levels as high as they are today. This makes Paul’s contention a non sequitur and refutes Paul’s argument, as illustrated in this expanded argument map:
This story of obfuscation by a presidential candidate has several additional dimensions. Besides claiming that humans won’t be harmed by continuing to burn fossil fuels, Paul argues that regulations to control emissions will hurt our economy. Two recent analyses (here and here) by separate groups of researchers independent of the government imply quite the opposite, as illustrated below:
Another set of researchers estimated that new regulations on emissions would prevent 3500 premature deaths per year, with the greatest benefit in states that rely heavily on coal such as Paul’s home state of Kentucky. How would you extend the argument map to incorporate this information?
Paul discussed only impacts of climate change on humans in his brief comments in the Republican debate. How about impacts on wild plants and animals? Humans have increased atmospheric carbon dioxide from 280 parts per million (ppm) before the Industrial Revolution to 400 ppm now, a level unprecedented in our history as a species. Global temperatures have increased correspondingly, and will continue to increase even if we gradually phase out use of fossil fuels. The rates of change in climatic conditions are also unprecedented, certainly in our history as a species and probably in the entire history of life on Earth. There have been five mass extinctions during Earth’s history, most recently about 66 million years ago when about 75% of all species became extinct, including all of the dinosaurs except their avian descendants. We are now in the midst of a sixth mass extinction, triggered by human activities such as overhunting, destruction of natural habitats, and burning of fossil fuels causing climate change. Many species of plants and animals can adapt to gradually changing climates, but adaptation to the rapidly changing conditions happening now is less likely.
I discuss argument mapping more fully in Tools for Critical Thinking in Biology, and illustrate another faulty argument of climate contrarians at a website with many other examples of argument maps. The Australian philosopher Tim van Gelder described the rationale for argument mapping and developed the software used for my argument maps, which can be found at the ReasoningLab website, together with links to tutorials and other resources for learning about argument mapping.