The problem with experts is that you can find one who advocates whatever you want. Do you think I exaggerate? Consider the case of Peter Duesberg.
Peter H. Duesberg, Ph.D. is a professor of Molecular and Cell Biology at the University of California.
He isolated the first cancer gene through his work on retroviruses in 1970, and mapped the genetic structure of these viruses. This, and his subsequent work in the same field, resulted in his election to the National Academy of Sciences in 1986. He is also the recipient of a seven-year Outstanding Investigator Grant from the National Institutes of Health.
Duesberg was, and is, an expert in retroviruses, like the HIV virus that causes AIDS. Well, we lay people think that HIV causes AIDS. Duesberg is not so sure:
On the basis of his experience with retroviruses, Duesberg has challenged the virus-AIDS hypothesis in the pages of such journals as Cancer Research, Lancet, Proceedings of the National Academy of Sciences, Science, Nature, Journal of AIDS, AIDS Forschung, Biomedicine and Pharmacotherapeutics, New England Journal of Medicine,nd Research in Immunology. He has instead proposed the hypothesis that the various American/European AIDS diseases are brought on by the long-term consumption of recreational drugs and/or AZT itself, which is prescribed to prevent or treat AIDS. See The AIDS Dilemma: Drug diseases blamed on a passenger virus.
I will not talk anymore about Duesberg's AIDS theories, I do not have the training, nor the desire to get that training. But Duesberg illustrates my main point: you can find an expert that believes whatever you want to be true.
That is the rub, "Whatever you want to be true." This is called confirmation bias. Wikipedia describes it:
Confirmation bias (also called confirmatory bias or myside bias) is the tendency of people to favor information that confirms their beliefs or hypotheses.[Note 1][1] People display this bias when they gather or remember information selectively, or when they interpret it in a biased way. The effect is stronger for emotionally charged issues and for deeply entrenched beliefs. People also tend to interpret ambiguous evidence as supporting their existing position. Biased search, interpretation and memory have been invoked to explain attitude polarization (when a disagreement becomes more extreme even though the different parties are exposed to the same evidence), belief perseverance (when beliefs persist after the evidence for them is shown to be false), the irrational primacy effect (a greater reliance on information encountered early in a series) and illusory correlation (when people falsely perceive an association between two events or situations).
So if you do not like meat, you quote Dr McDougal; if you do like meat you quote Dr Perlmutter. If you think saturated fat is bad for you, there are many doctors that will agree with you, like Dr Barron at UCSF's obesity center. If you like saturated fat, then you can quote Dr Davis or Dr Sinatra, both expert cardiologists. I do not expect you to know who any of these doctors are, but as the weeks go on, if you stick with me, you will.
So we will then rely on the consensus of the medical community. Well, er, no. According to Thomas Kuhn in his book The Structure of Scientific Revolutions, one cannot rely on that. Here is Wikipedia's description of his theory.
Kuhn made several notable claims concerning the progress of scientific knowledge: that scientific fields undergo periodic "paradigm shifts" rather than solely progressing in a linear and continuous way; that these paradigm shifts open up new approaches to understanding what scientists would never have considered valid before; and that the notion of scientific truth, at any given moment, cannot be established solely by objective criteria but is defined by a consensus of a scientific community.
In other words, sometimes the consensus is dead wrong.
The best example of this is the replacement of butter by margarine that started in the 60's. I special-ordered a used book written by a doctor in the 1960's. He wrote very much against the consensus of the time and advocated that people use margarine and not butter. Gradually his position became the consensus and butter was said to be a very bad food. (Sorry for being vague about this doctor's name, the book is in another state.) Just a few short years ago if you said margarine was not healthy, you would have been ridiculed. Well, the consensus has changed again!
Although trans fats are edible, consumption of trans fats increases the risk of coronary heart disease by raising levels of the lipoprotein LDL (so-called "bad cholesterol") and lowering levels of the lipoprotein HDL ("good cholesterol").
In science circles this is called a whoopsie. In fact, trans fats are so bad that the FDA may ban them. The same Wikipedia article tells us:
The FDA has issued a preliminary determination that partially hydrogenated oils (which contain trans fats) are not "generally recognized as safe", which is expected to lead to a ban on industrially produced trans fats from the American diet.
(Note that many margarines have been reformatted and no longer contain trans fats. And also note that any deep-fried food will contain a small amount of trans fats from the frying process and the fact that fat is only changed once a week in a restaurant.)
Of course the conclusion we should draw is to eat more butter. Well, again no, not necessarily. In the logic field this is called the fallacy of the false dilemma. It may be that both are unhealthy. I do not know. In fact my guess is that the evidence is inconclusive and no one knows. Since margarine is a fake food, I avoid it. But I also limit my butter use. I think that a far better choice is olive oil. (This will be a blog post at a later time.)
So you can conclude that I will not be following the current fad and adding butter to my coffee.
I think the best way to conclude today's post is comedy. In the Woody Allen movie Sleeper, Woody, a hypochondriac Health Food store owner, is frozen. When he is revived, his doctors are shocked by his request for health food.