Australasian Science: Australia's authority on science since 1938

Confirmation Bias, Denialism and Morton’s Demon

By Peter Bowditch

Science is a search for truth, but three filters can prevent the truth from being recognised.

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Anyone who has ever conducted research will be familiar with the problem of confirmation bias – hearing what you want to hear. Anybody doing research in the social sciences has to be constantly aware of the possibility of selecting results and readings that fit the hypothesis and either ignoring or eliminating things that don’t quite fit.

I don’t mean rejecting obvious outliers, where the observations are so far from the rest and therefore a mistake can be assumed. I mean shaving the results to suit what the experimenter expects to find. This may not even be a conscious act, because doing it consciously approaches fraud and most people are basically honest.

The classic case of confirmation bias in the hard sciences is cold fusion. Ponds and Fleischmann found what they wanted to find and then stopped looking.

In the social sciences there was Cyril Burt’s just-too-good statistics about separated twins, and Margaret Mead’s willingness to believe whatever some young girls told her.

In medicine there was William McBride’s work on Debendox.

I don’t think any of these people started out to do the wrong thing, but they all did it anyway because they wanted to confirm their beliefs.

Confirmation bias is rife in paranormal research, largely because this research is carried out by true believers. While there have been cases of deliberate...

The full text of this article can be purchased from Informit.

Peter Bowditch is Immediate Past President of Australian Skeptics Inc. (