We are told that there is a scientific consensus on the cause of climate change. Pope Francis published his new encyclical on the subject and also talks about a scientific consensus. What should the average layperson believe? Jay Richards has written a helpful piece with the title, “When to Doubt a Scientific Consensus.” He reminds us from the history of science “that scientists are not immune to the non-rational dynamics of the herd.” So when do we accept what scientists say, and when should we be skeptical? He describes twelve tests. Let me mention three of them. First, we should be skeptical when different claims get bundled together. With climate change there are actually four claims: the earth is getting warmer, human emissions are the cause, it’s going to be catastrophic, and we have to transform society and world economies to deal with it. The first one is generally accepted. There has been a warming trend since 1850. But that doesn’t mean that humans are the primary cause. Even if they are, the last two claims should be open to lots of debate and discussion. Second, we should be skeptical when ad hominem attacks against dissenters predominate. You have probably heard the legal proverb: If you have the facts on your side, argue the facts. If you have the law on your side, argue the law. If you have neither, attack the witness. If you question climate change these days, you will be labeled a global warming denier on par with a Holocaust denier. Third, we should be skeptical when consensus is declared hurriedly or before it even exists. A true scientific consensus takes time and should take place in an open discussion where various scientific studies are given an opportunity to prove or disprove a theory. For more than a decade, we have heard that “the time for debate” is over and that the “science is settled.” That would come as a surprise to the many climatologists who completely disagree. Should we doubt the climate change scientific consensus? Jay Richards gives a dozen good reasons why we should.