Measles, global warming and the construction of knowledge

by George Hatjoullis

English: Relationship between declining # of p...

English: Relationship between declining # of pirates and increasing global temperatures. (Photo credit: Wikipedia)

What, you might ask, do measles and global warming have in common? They are both examples of how science interacts with the lay community to construct knowledge. The concept of knowledge construction is not, ironically, universally accepted. The popular view, especially amongst scientists, is that knowledge is lying around waiting to be uncovered and the role of science is to uncover it. If this were the case then knowledge would be a fairly robust form of meaning and it clearly is not.

Consider the measles outbreak in the UK. It has arisen because a single scientist suggested that he had evidence that the Measles, Mumps and Rubella vaccine was causally linked to autism. The vast body of scientists insisted that the vaccine was not so linked but many parents chose to risk the underlying diseases for their child rather than expose them to some alleged risk of autism. The work of the sole scientist was later discredited but the damage was done and a suspicion of MMR vaccine lingered. The interesting question is why parents were so willing to ignore the establishment and act on the basis of the work/assertion of one scientist?

Few if any of the parents were able to critique the work of either the establishment or the lone scientist. It came down to who they chose to believe. Even today it is possible to find parents that still suspect the lone scientist may have been correct. The mere assertion of this scientist had created a new form of knowledge, namely a possible link between MMR and autism. Nothing was uncovered. Knowledge was constructed. It was constructed via the interaction between someone deemed to have authority in knowledge and the desired psychological belief needs of the non-scientific mass of people.

Suspicion of the ‘establishment’ runs deep. It is more evident in some nation states than others but it is present to some degree in all populations. It manifests itself in many ways with conspiracy theories perhaps the least healthy of such social developments. The reason the MMR/autism knowledge could be constructed is because people were willing to believe that the establishment might ignore a small, but significant, risk of autism in order to achieve the greater good of avoiding an epidemic of one or more of the three diseases. In effect they believe that the underlying social philosophy of the establishment is utilitarian. In this respect they may be correct but that does not mean there is any link between MMR vaccine and autism.

The other factor at work is the widespread use in science of probability theory and the incorrect assumption that individuals make ‘rational’ decisions based on probability theory. It was probably understood that the risk of their child contracting one or more of the three diseases was high if no one used the MMR vaccine and the risk of autism very small (according to the lone scientist’s work). However, the seriousness of the three diseases may have been judged (incorrectly) to be low whilst the consequences of autism very serious. There is a common tendency to avoid much feared outcomes even at very high cost even if a probability analysis suggests the cost is not in some sense worthwhile. Decision making under uncertainty does not lead to the same outcomes as decision-making under probability theory.

For example, assume a parent has £100 to last the month and two children to feed. At the start of the month someone offers him/her a bet that has a verifiable chance of 80% of paying off. The payoff is £1000 so the expected value is £800. Tempting but what if the 20% chance of losing kicks in? How does the parent feed those children. The vast majority of parents, I suspect, would not gamble with the food on the plate of their children. Sadly, one or two might.

These issues apply in most establishment science debates. The one that interests me here is global warming. There has been a lot of research and everyone seems to have a strong opinion. Yet the overwhelming majority are not equipped to judge the research for themselves. So on what basis are the strong views formed?

The evidence is not hard to understand. ‘Global temperatures‘, having been stable over most of the last 2000 years, suddenly jump towards the 20th century, at the same time as global industrialisation took off along with the burning of vast quantities of fossil fuels. The correlation is judged causal by some and coincidence by others. Which camp are you in?

Now one might ask questions about what is meant by ‘global temperatures, and how this is measured over the last 2000 years. However, what would be the point as one has no way of judging the process. Moreover, it does seem plausible that global temperatures have changed before so why not now? Accepting that global warming has occurred is an act of faith (unless you have checked the evidence yourself of course) but a reasonable one. Why would establishment science lie about this?

The big debate seems to be over causality. Correlation is not proof of casuality. Causality is a plausible theory and is consistent with various bits of knowledge that have been constructed over time. However, few can establish this for themselves and accepting this to be the case is again an act of faith in the establishment of science. Why were so many willing to believe the establishment of science on this issue but also willing to believe one dissenter on the MMR vaccine?

The answer is probably, in part, for the same reason, namely decision making under uncertainty. Global warming is projected to have catastrophic consequences for human life on this planet. If there is any chance this is true then many people would prefer to proceed on the basis of this assumption and act accordingly even if the cost of acting is high. There is not much point in risking destroying human life on this planet. In fact it is quite reassuring to believe humanity has caused the observed global warming as then there is more chance that humanity can control the process. So knowledge is constructed once again, in this case the concept of man-made global warming.

P.S.  4/08/2016

When I speak of checking the data I do not simply mean reading the conclusions of others on the Web. I mean exploring methods of data collection, statistics, experimental design etc. 99.9% of the population are not equipped to do this and even those of us that are have other things to do. Acceptance of evidence depends upon the authority of science. This authority is evidently quite variable. I am offering one possible explanation as to why (decision making under uncertainty). It also allows me to illustrate how knowledge is constructed rather than uncovered. I am not questioning the seriousness of climate change or the role of human activity in causing it. How could I? I have not checked the data.