On the Epistemology of Consensus

Some might say that we are flogging a dead horse here, but during the ongoing discussions concerning consensus and whether it is a valid indicator of the “truth” of a scientific theory, it is worth pointing out that Spiritual Anthropologist, has made some interesting points. I will attempt to distil his main points in order to clarify them and see if they stand up to scrutiny.

  1. We can only falsify scientific theories and not confirm them. Confirmation is often confused with coherence. “Science can only falsify. It cannot confirm.” and “We can show that a theory is false, through a statistical version of proof by contradiction. We cannot show that it is true, to any extent. We lack the inductive machinery to do that.”
  2. There is no data to suggest that scientific consensus is a valid reflection of (scientific) truth: “I’m still waiting for empirical data consistent with the assertion that the percentage of scientists that agree with a theory is a valid measure of the robustness of a theory.” and “if you want to show that the views of scientists and the analysis of “pro” vs “con” in papers are indeed valid indicators of robustness of a theory, then you need to actually provide observation on that.”


The big problem here is that this whole debate concerns epistemology and thus is rather dependent on what your particular theory of knowledge and truth might be. In the discussions we have had, commenters and myself have touched upon ideas of objective truth, coherentism and pragmatism, amongst others. Coherentism is related to point 2) where truth can be assumed if a claim is coherent with a given framework. This works both ways – a claim is true if it coheres with a system of beliefs, and a system is true if the claims within it cohere.

Pragmatism has similar elements – where truth is not in some Platonic realm. Instead, it is about how pragmatic it is, about how the belief matters in the world.

I mention both of these theories because they arguably have a huge effect on whether we can say that a consensus in science has any reflection on truth or the robustness of a theory. Spiritual Anthropologist (SA), who is claiming the above, uses words like robust but doesn’t really define them and so we can easily claim that a theory is robust if it does a good job of cohering with other theories and is usable. In terms of a consensus, this is arguably an important implicit characteristic of a claim or theory. To take climate change and AGW as an example, it is both coherent with a whole host of other claims (indeed, it is dependent on other claims, and so coherence is a given – it’s sort of why so many scientists believe it) and pragmatic. It certainly has hugely pragmatic implications.

In these terms and in this case, the scientific consensus is very much a reflection of a robust theory. Yes, there are fuzzy edges but this is what the scientific process works so hard to refine.

To Quoque, my friend

One of the biggest criticisms against SA is that his own criticisms can be levelled directly back at him. He states things like:

“I’m still waiting for empirical data consistent with the assertion that the percentage of scientists that agree with a theory is a valid measure of the robustness of a theory.”

The thing is, I can reverse this:

I’m still waiting for empirical data consistent with the assertion that the percentage of scientists that agree with a theory is NOT a valid measure of the robustness of a theory.

He keeps ramming home this notion that we need an empirically evidenced piece of research to show that consensus is a good indicator of “robustness”, but fails to see that for the negation of this, he also needs to offer evidence. Because what is really happening here is pro-consensus is asserting something, and “anti”-consensus is asserting in rebuttal.

This falsification charge can also be levelled at his claim, too. You cannot confirm either claim, only falsify them. Which one gets falsified?

Of course, the claim of the usefulness or robustness of consensus is only a generalisation, not an absolute law.

Consensus as a reflection of robustness

I understand why he would call for research evidence as if we are making a positive claim on the value of consensus, then we should at least present some evidence to support this. This is admirable as a demand. However, it also works on him. If he is claiming that consensus is NOT a valid indicator of robustness, then I would like to see some evidence of that too. Some scientific research.

This could, of course, mean that we are at a stalemate. Perhaps. Perhaps not.

You see, I think consensus is pragmatically and coherently attractive on a very regular basis and we don’t really think about it. Evolution fits. It coheres wonderfully across so many domains. This leads experts in the field to recognise its robustness, and therefore a consensus forms. This coherent belief or system of beliefs is then very useful in understanding other claims and beliefs.

In other words, consensus is a reflection of coherence and pragmatism. It is precisely as a result of their robustness that scientists adopt theories in a consensus manner. And I don’t need a journal to tell me this – this is implicit in the very nature of the beast.

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