"Climate Change and Argumentative Fallacies"

Julian Sanchez has posted on his blog an interesting piece on the logic of debate on climate change, taking off on an article in National Review by Jerry Taylor. The posts deal with how one judges the merit of an argument in public debate, when those arguments purport to be based on scientific evidence. As the title suggests, the specific issue of concern is whether there is scientific evidence of anthropogenic climate change. It seems clear that most scientists studying the climate feel that there is such change, but there is a vocal minority arguing that the evidence of such change is not convincing.

Think about the problem of predicting the change in climate over the next century, and the portion of that change that will be due to the emissions of greenhouse gases and other actions by mankind. This is not like predicting the paths of the planets. Even figuring out the average temperature over the globe for the last few years is difficult with room for error, and figuring out an accurate value for the rate of change involves data collection problems and computer analysis about which experts can differ. Even more complex are the computer models that are used to study the links between emissions and climate, and those to extrapolate emissions and climate change.

Using a model of proof drawn from high school geometry is not helpful. Demonstrating that there is sufficient evidence of anthropogenic global warming is radically different than proving a theorum in geometry. Moreover, there are at least two different levels of demonstration going on:

• that within the scientific community which I think of in terms of a paradigm change in which scientists debate the details (and in which we can only expect consensus when the most reactionary scientists die);
• that of the public in which the issue is which scientists to believe.

Even within the scientific community, the questions faced in studying climate change involve so many disciplines that even were someone able to review all the data and check all the analyses (which are not possible) no one has the breadth of expert knowledge to do so alone. Thus everyone is in a possition of estimating the trustworthyness of scientists based on their actions and performance.

Note that this is not a scientific experiment. At some crazy level, it would be most interesting to continue on our current course of creating more and more greenhouse gas emissions and measure the results in temperature, sea level rise, etc. at the end of the century, comparing those results with the predictions made now. But of course, that is crazy.