Scientific consensus seems a reasonable concept. If a great number of individual scientists arrive at a similar opinion this is generally a sufficient reason to have confidence in those views. Skeptics about scientific consensus often use examples of scientific views that started out as a minority view to become the majority view later. Although these examples raise interesting questions about how science evolves as a collective undertaking, they cannot be used to argue against the importance of scientific consensus as such. For every minority view that became a majority view there are a lot more examples of crackpot theories that are still crackpot theories today. Nevertheless, there are a number of situations where the concept of scientific consensus is of limited value.
A good example are fields that are so interdisciplinary that there is no clearly identifiable group of scientists who can be perceived as authorities on the matter. For example, what is the scientific consensus on cryonics? The consensus of biologists? The consensus of cryobiologists? The consensus of neuroscientists? The consensus of experts on nanotechnology? The consensus of those who study cryonics in all its aspects? It is clear that when there is no clearly identifiable group of experts, the concept of scientific consensus becomes problematic. Another example of cases where the concept of scientific consensus is of limited use is when the scientific issue in question concerns such a marginal field of inquiry that few people can be considered qualified to comment on it. Only the people who are engaged in the field can be considered experts whose views should matter. Obviously, this presents a major problem for evaluating such views because the marginal nature of the field can either reflect some real innovative research or complete hokum. In those cases the best approach is to evaluate disputed claims on general scientific criteria. Can the claims be substantiated through empirical observations? Which observations would confirm or falsify the hypothesis? etc. Many crackpot views can be dismissed on methodological grounds alone.
There are areas of research where the concept of scientific consensus completely breaks down. These are areas of research in which one of the competing views is culturally or politically controversial. This can range from mild disapproval to outright hostility and persecution of those who express them. Throughout history there have been many examples of views that were not even allowed to be expressed, often because its widespread dissemination and acceptance would undermine the existing scientific, religious, or political establishment. When an individual researcher has a strong incentive not to engage in a field of research or express his/her views about it, the practice of simply counting the number of people in favor and against a view to establish scientific consensus is utterly unreliable. Unfortunately, it is exactly in fields that are (politically) controversial that people like to abuse the concept of scientific consensus; climate change, evolutionary psychology, heredity and intelligence, animal research etc. There is little value in stating that the majority of someone’s colleagues reject a view when the price of embracing such a view is the end of an academic career, or in some countries, political persecution.
Then there are areas of inquiry that are such a draw for people with non-scientific motives that the whole field can become a dubious undertaking. The social sciences and philosophy suffer from this kind of academic activism. The field of macro-economics is currently one of the worst examples of a politicized science in which scientists cannot even seem to agree on the meaning of the terms that are used. Strangely enough, this condition does not produce more humility but increased arrogance among its practitioners.
Is there anything that can be done to bring sanity to these controversial fields of research? For an answer we may want to look at the natural sciences. There is no such thing as “conservative physics” or “feminist chemistry.” This is useful because any credible science can be reduced to the science of physics (or mathematics). Biology can be translated into biochemistry. Biochemistry can be translated into physics. Such an effort will give some scientific endeavors a firm foundation but will expose other areas of research as methodologically immature.
This position is prone to be misunderstood. For example, it does not necessarily mean that one should prefer “nature” over “nurture” in scientific disputes about behavior. If “genes” and “environment” are properly conceptualized they will both refer to the same material world that can be investigated through scientific means. Unless one wants to argue that the “environment” works its way through unknown mysterious ways into the soul, the researcher who argues that behaviour is predominantly shaped by a person’s environment should be expected to present such views in the language of neuroscience and biochemistry. Unfortunately, few “environmentalists” are prepared to do so.
One obvious objection to this position is that it will leave us with little we can have great confidence in. In other words, we would often feel compelled to simply say “I don’t know.” But there should be no shame in that. It is better to be modest than to be arrogant.
Further reading: Robert Higgs – Peer Review and Scientific Consensus