My husband and I had a conversation about science on the way home from church yesterday. Since he is a scientist, it drives him a little buggy when people talk about “consensus” as a way e to a scientific conclusion, or that scientific facts can be “bent” to uphold a particular opinion or viewpoint. As he said, science is about discovery and fact, not about agreement. One hundred people can agree that grass is, in fact, a mammal, but that is not science, nor is there scientific evidence to uphold that claim.

Jay Richards gives us a litmus test for scientific evidence. When should we be skeptical of science?

First, be skeptical when different claims get “bundled” together.

Usually, in scientific disputes, there is more than one claim at issue. With global warming, there’s the claim that our planet, on average, is getting warmer. There’s also the claim that human emissions are the main cause of it, that it’s going to be catastrophic, and that we have to transform civilization to deal with it. These are all different assertions with different bases of evidence. Evidence for warming, for instance, isn’t evidence for the cause of that warming. All the polar bears could drown, the glaciers melt, the sea levels rise 20 feet and Newfoundland e a popular place to tan, and that wouldn’t tell us a thing about what caused the warming. This is a matter of logic, not scientific evidence. The effect is not the same as the cause.

Don’t assume that “consensus” equals science.

Next, be skeptical when ad hominem attacks against skeptics is the norm, rather than an open scientific dialogue.

It’s easier to insult than to the follow the thread of an argument. And just because someone makes an ad hominem argument, it doesn’t mean that their conclusion is wrong. But when the personal attacks are the first out of the gate, and when they seem to be growing in intensity and frequency, don your skeptic’s cap and look more closely at the evidence.

When es to climate change, ad hominems are all but ubiquitous. They are even smuggled into the way the debate is described. mon label “denier” is one example. Without actually making the argument, this label is supposed to call to mindthe assertionof the “great climate scientist” Ellen Goodman: “I would like to say we’re at a point where global warming is impossible to deny. Let’s just say that global warming deniers are now on a par with Holocaust deniers.”

Third, Richards warns us to be skeptical when scientists are being pressured to “agree” with a claim, despite the fact that scientific evidence does not bear out that claim. That is propaganda, not science; Richards points to the Soviet Union and its treatment of scientists as an example. When a “voluntary elite” decide upon “truth,” there are issues. While we’re not living under a regime, when scientists get pressured and there are big strings attached (think tenure), we should be skeptical.

Fourth, peer review and publishing should not be “cliquish.”

Though it has its limits, the peer-review process is meant to provide checks and balances, to weed out bad and misleading work, and to bring some measure of objectivity to scientific research. At its best, it can do that. But when the same few people review and approve each other’s work, you invariably get conflicts of interest. This weakens the case for the supposed consensus, and es, instead, another reason to be suspicious.

Richards says we should also be skeptical when consensus is declared before there are results to bear it out. Scientific evidence takes time to e apparent. One or two papers does not a consensus make.

Scientists around the world have to do research, publish articles, read about other research, repeat experiments (where possible), have open debates, make their data and methods available, evaluate arguments, look at the trends, and so forth, before they e to agreement. When scientists rush to declare a consensus, particularly when they claim a consensus that has yet to form, this should give any reasonable person pause.

Richards’ final point is that we should be skeptical when we are told there is a scientific consensus. Again, science is not about agreement. It’s about fact, evidence, and conclusions based on scientific method.

No one talks about the consensus that the planets orbit the sun, that the hydrogen molecule is lighter than the oxygen molecule, that salt is sodium chloride, that light travels about 186,000 miles per second in a vacuum, that bacteria sometimes cause illness, or that blood carries oxygen to our organs. The very fact that we hear so much about a consensus on catastrophic, human-induced climate change is perhaps enough by itself to justify suspicion.

Read Richards’ entire piece at The Stream.