Evidence That
Demands a Verdict

20 May 2013

A photo of Earth taken from Apollo 11. NASA
A photo of Earth taken from Apollo 11.

There’s a popular picture traversing the net recently that states 97% of climate scientists believe that anthropogenic global warming is true. More specifically, that of peer reviewed climate research papers, of the ones that made a statement on the cause of global warming, 97% agreed that humanity was the cause.

You can imagine the lively discussions it induced.

There are certain areas of science that people find deeply controversial. In climate science it’s global warming. In biology, it’s evolution. In astrophysics it’s the big bang, or to a lesser degree things like dark matter. The experts in these fields don’t find these controversial at all. The big bang happened, evolution is real, and humans are a principal cause of global warming.

The researchers in these fields have moved beyond those basic facts and are investigating the details. Did the early universe have an inflationary period, and if so, how long did it last? How did bipedalism arise in early primates? Why is the rate of global temperature increase slower than expected? And yet in the popular press and blogs they are barraged with doubt.

In astrophysics we have it pretty easy. Big bang hecklers usually just argue that we don’t really know because we weren’t there, or that because we don’t know the exact cause of the big bang we don’t know anything about cosmic evolution. We aren’t generally accused of being part of a cabal that only “agrees” on the big bang to support a philosophical or social agenda, or that we’re simply promoting the big bang for the money. Those arguments are applied to evolutionary biologists and climate scientists.

A 97% poster.
A 97% poster.

This is why you have things like the 97% image. On the face of it, the 97% argument is rather meaningless. It doesn’t matter whether 97% agree or 9% agree. Science is not a democracy. You don’t get to declare what is true by consensus. What matters is what the data tells you. What matters are the theories that work. It also meaningless that 3% don’t agree with anthropogenic global warming. Not every astrophysicist agrees that the big bang is real. I once met a physicist who didn’t think photons exist. I’m sure if I searched hard enough I could find one that thinks the Earth doesn’t move.

What the 97% argument does do is raise a specific question: at what point does a reasonable non-specialist concede that the scientists are right? In the case of the big bang, I can (and have) present the evidence we have for the big bang. If you search the internet you can find evidence arguments against the big bang. I can explain why I don’t find those arguments compelling, and note that the vast majority of astrophysicists find the evidence for the big bang to be compelling.

If you still aren’t convinced, that’s about as far as we can go. You aren’t obligated to believe me, but I’m also not obligated to convince you. But if the reason you aren’t convinced is because you don’t think there’s enough evidence yet, or because you know of a scientist that disagrees with the majority, then you are basically arguing that the majority of experts in the field are either confused or disingenuous. Basically it means you just don’t trust them. Hence the assertion that evolutionists are promoting atheism, or that climate scientists are committing fraud to make money.

Because if 97% of people who have devoted their lives to mastering a scientific field have looked at the evidence and come to the same conclusion. If they are earnest and honest in their search for the truth, and have been convinced by the evidence, then that is a compelling argument that the theory is sound. Without becoming an expert yourself, the only counter is to doubt their veracity.

That might sound like I’m saying there’s no room for dissension from the general public. That you should either agree with “us experts” or you’re an idiot. This isn’t the case at all. There is room for disagreement in science. No theory is above reproach, and it is always possible that new evidence can overturn a long-held theory. But your disagreement does not invalidate a particular theory. Calling anthropogenic global warming nonsense, for example, doesn’t change the fact it’s the best model we have.

Science is about questioning results, but there also comes a time where the evidence we have demands a verdict.