Guest essay by Eric Worrall

A lecturer in critical thinking has demonstrated his technique for defeating climate skepticism.

How to use critical thinking to spot false climate claims

February 7, 2018 3.46pm AEDT

Peter Ellerton

Lecturer in Critical Thinking, Director of the UQ Critical Thinking Project, The University of Queensland

Much of the public discussion about climate science consists of a stream of assertions. The climate is changing or it isn’t; carbon dioxide causes global warming or it doesn’t; humans are partly responsible or they are not; scientists have a rigorous process of peer review or they don’t, and so on.

Despite scientists’ best efforts at communicating with the public, not everyone knows enough about the underlying science to make a call one way or the other. Not only is climate science very complex, but it has also been targeted by deliberate obfuscation campaigns.

If we lack the expertise to evaluate the detail behind a claim, we typically substitute judgment about something complex (like climate science) with judgment about something simple (the character of people who speak about climate science).

But there are ways to analyse the strength of an argument without needing specialist knowledge. My colleagues, Dave Kinkead from the University of Queensland Critical Thinking Project and John Cook from George Mason University in the US, and I published a paper yesterday in Environmental Research Letters on a critical thinking approach to climate change denial.

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Six steps to evaluate contrarian climate claims

Identify the claim: First, identify as simply as possible what the actual claim is. In this case, the argument is:

The climate is currently changing as a result of natural processes.

Construct the supporting argument: An argument requires premises (those things we take to be true for the purposes of the argument) and a conclusion (effectively the claim being made). The premises together give us reason to accept the conclusion. The argument structure is something like this:

Premise one: The climate has changed in the past through natural processes

Premise two: The climate is currently changing

Conclusion: The climate is currently changing through natural processes.

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Check for ambiguity: The argument mentions climate change in its premises and conclusion. But the climate can change in many ways, and the phrase itself can have a variety of meanings. The problem with this argument is that the phrase is used to describe two different kinds of change.

Current climate change is much more rapid than previous climate change – they are not the same phenomenon. The syntax conveys the impression that the argument is valid, but it is not. To clear up the ambiguity, the argument can be presented more accurately by changing the second premise:

Premise one: The climate has changed in the past through natural processes

Premise two: The climate is currently changing at a more rapid rate than can be explained by natural processes

Conclusion: The climate is currently changing through natural processes.

This correction for ambiguity has resulted in a conclusion that clearly does not follow from the premises. The argument has become invalid once again.

We can restore validity by considering what conclusion would follow from the premises. This leads us to the conclusion:

Conclusion: Human (non-natural) activity is necessary to explain current climate change.

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