Consensus rules, OK? Or not.

In the discussion I had with John T Mullen on BioLogos, he criticised my skepticism about evolutionary psychology as a truth-finding discipline, including the following argument to which I did not reply then, but which seems worth examination in its own right:

[T]hough we cannot pronounce on the specific claims made by either side, we can (if we have a broad-based education) identify when a consensus exists within a given scientific community, and we are rationally obligated to accept the conclusions of the consensus. Outsiders must not judge another discipline’s consensus.

Now remember that the overall discussion was about whether evolutionary science necessitates significant changes to the Christian doctrine of sin. The point seems to be that if the guild of evolutionary psychologists holds a consensus that selfish behaviours evolved, the outsider is obliged to accept it. That means not simply accepting that it is a consensus, but that as a consensus it is true.

I have some problems with that, even though I am an outsider to the philosophy of science. The only one I raised, obliquely, in my reply on BioLogos was that sciences once held to be respectable, such as phrenology, astrology or, in psychology itself, Freudian psychoanalytic theory, have now been rejected en bloc as legitimate research programmes. Yet within them they maintained consensus positions on their core conclusions.

Would, therefore, an outsider (a theologian, say) back in the seventeenth century, on the basis of Scripture’s skepticism for astrology, have been wrong to reject the astrological consensus, as a rational obligation? One might rightly argue that, at the time these sciences were mainstream, it would have been understandable to accept their conclusions. For example, a review of the available evidence before (and even after) Galileo, that persuaded the majority to form a consensus for geocentrism, shows that they were entirely rational – arguably more so than the pioneers who had an intuition it was wrong. But does that mean an educated non-astronomer/astrologer, like some of the Jesuits, say, would have been irrational, or even simply presumptuous, to doubt the majority and say, “I reckon that Copernicus boy may be on to something”?

But a second objection to the idea that outsiders should routinely accept the consensus of a branch of science is that separate disciplines often develop opposing beliefs on major issues, sometimes because they approach the subject from different angles, and sometimes because the guild is formed because of dissent from the consensus.

If we take the instance of Freudianism, which was hugely influential even up to the time I studied it in the 1970s, it was a field which was opposed to, and by, the now ityself eclipsed discipline of behavioural psychology. It was even opposed in many central respects by rival psycholanalytic theories like that of Carl Jung. So which consensus was binding on the educated outsider? Not all of them, if he was to avoid intellectual chaos.

The same can be said of current debates. In biology, for example, there is apparently unbridgeable disagreement between phylogenies based on palaeontology and morphology, and those of the geneticists. One day those may, or may not, be resolved, but in the meantime two opposing consensus positions cross the disciplinary divide. It would be quite conceiveable in theory for such a dispute to affect a theological issue, for example the evolutionary stage at which speech and therefore reason developed. One consensus, perhaps, might suggest that only Homo sapiens ever had true speech. The other, perhaps, that the relevant genetic endowment existed in the Australopithecines. On which consensus is one obliged to base ones theology of human origins?

But there is one more factor that, I think, shows the irrationality of the principle that one must be ruled by the consensus of a scientific specialty other than ones own. And it shows the unconscious soft scientism of the principle itself. Remember that in our conversation a philosopher and a medic (outsiders to evolutionary biology) were disagreeing on whether it is necessary to reformulate Christian doctrine. But settling Christian doctrine is the business of theologians and duly-called church leaders, is it not? And although I have studied theology and was a local church leader, neither of us is a professional theologian or Ecumenical Council.

So surely, on the principle we’re discussing, we’d both be rationally obliged to accept the consensus of those within the theological discipline as truth. As, indeed, would the evolutionary biologists, being outsiders to it. An interesting conundrum that, isn’t it?

But one might point out that Christian theology is a vastly bigger academic fellowship than evolutionary psychology will ever be, and that its consensus on the origin of human sin has been developed over several thousand years. Why would the queen of sciences be subject to revision by one small and controversial branch of the far-from-settled science of evolutionary biology?

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About Jon Garvey

Training in medicine (which was my career), social psychology and theology. Interests in most things, but especially the science-faith interface. The rest of my time, though, is spent writing, playing and recording music.
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