"Social Scientists call it 'Cascade Theory' " - Examining current issues in science and society

Philosophical Investigations - Examining current issues in science and society

Social Scientists call it 'Cascade Theory' - the idea is that information cascades down the side of an 'informational pyramid' - like a waterfall.

How many waterfalls really do cascade down pyramids?

Not many. But that is not the point. It is easier for people, if they do not have either the ability or the interest to find out for themselves, to adopt the views of others. This is without doubt a useful social instinct.

As it has been put, Cascade theory reconciles 'herd behaviour' with rational-choice because it is often rational for an individual to rely on information passed on to them by others........

Propaganda

In the words of Freud's nephew, Edward Bernays (1891-1995, whose rather mundane sounding day-job was as a theatre promoter) human wants and desires are "the steam that make the social machine work" (Propaganda, 1928). Properly handled, the pressure of public opinion can be controlled as if "actuated by the pressure of a button". The herd, he noted, like to follow the example of a trusted authority figure. ailing that, it relies upon "clichés, pat words or images which stood for a whole group of ideas or experiences".

Unfortunately it is less rational to follow wrong information, and that is what can often happen. We find people cascading uselessly, like so many wildebeest fleeing a non-existent lion, in so many everyday ways. A lot of economic activity and business behaviour, including management fads, the adoption of new technologies and innovations, not to mention the vexed issues of health and safety regulation, reflect exactly this tendency of the herd to follow poor information.

Some people say that what is needed in response is to encourage a range of views to be heard, even when they are annoying to the 'majority'. Like, for instance, one should allow people to 'deny' global warming. Or let teachers in schools and universities decide what they are going to teach. But more people say, on the contrary, that what is needed is stricter control of information to stop 'wrong views' being spread. It is that view that is cascading down the pyramid now.|

One of the best examples of 'cascade theory' is that of the entirely false consensus that built up in the 1970s around the danger of 'fatty foods'. In fact, this consensus still exists - but has never had any medical or scientific basis.

The theory can be traced back in this case to a single researcher called Ancel Keys, who published a paper saying that Americans were suffering from 'an epidemic' of heart disease because their diet was more fatty than their bodies were accustomed to after thousands of years of natural evolution.

In 1953, Keys added additional evidence from a comparative study of US, Japan and four other countries. Country by country, this showed that a high fat diet coincided with high rates of heart disease.

Unfortunately, for this theory, it turned out that such prehistoric ‘traditional diets’ were not especially 'low fat' after all - indeed, even the imaginary hunter-gatherers of yore, if they relied on eating their prey, would have had more fat in their diet than most people do today. As Science magazine pointed out, in the most relevant period of a hundred years before the supposed 'epidemic' of heart disease, Americans were actually consuming large amounts of fatty meat, so the epidemic followed a reduction in the amount of dietary fat Americans consumed – and not an increase.

The human brain is designed to see patterns in raw data - even when they may not really exist.

Keys' country-by-country comparison had also been skewed – for as critics at the time pointed out, many countries did not fit the theory, (the obvious cases being France and Italy, with their oily, fatty cuisines) but Keys simply excluded them. The American Heart Association, considered to be the voice of experts in this case, even issued a report in 1957 stating plainly that the fats-cause-heart-disease claims did not "stand up to critical examination". Even the case for there being any such epidemic was dubious too - the obvious cause of higher rates of heart disease was that (like the Soldiers in the First World War in their tin hats, see Investigation 85) - people were living longer. Long enough to develop heart disease. But it was too late, the cascade had started.

Three years later, the Association issued a new statement, reversing its view. The Association had no new evidence but had, rather, some new members writing the report, in the form of Keys himself and one of his friends. The new report made the cover of Time Magazine, and was picked up by non-specialists at the US Department of Agriculture who then asked a supporter of the theory too draw up 'health guidelines' for them. Soon, scarcely a doctor (if a few specialised researchers still protested) could be found prepared to speak out against such an overwhelming 'consensus'. And all this was good enough for the highest medical officer in the United States - the Surgeon General - in 1988 to issue a doom-laden warning about fat in foods zealously claiming that ice cream was a health-menace on a par with tobacco smoking. 

It was really a pretty silly theory, and certainly not one based on good evidence. In fact, in recent years, large scale studies in which comparable groups have been put on controlled diets (low-fat and high fat) a correlation has at last been found. It turns out that the low-fat diet seems to be unhealthy! But no one is quite sure why. 

So the next time someone says that 'all the experts agree' - even if they are philosophers, Nobel Prize winners, or even TV personalities - don't be so sure that that proves anything at all.

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