When Is Intuitive Judgment Valid?

(p. 240) If subjective confidence is not to be trusted, how can we evaluate the probable validity of an intuitive judgment? When do judgments reflect true expertise? When do they display an illusion of validity? The answer comes from the two basic conditions for acquiring a skill:

  • an environment that is sufficiently regular to be predictable
  • an opportunity to learn these regularities through prolonged practice

When both these conditions are satisfied, intuitions are likely to be skilled. Chess is an extreme example of a regular environment, but bridge and poker also provide robust statistical regularities that can support skill. Physicians, nurses, athletes, and firefighters also face complex but fundamentally orderly situations. The accurate intuitions that Gary Klein has described are due to highly valid cues that the expert’s System 1 has learned to use, even if System 2 has not learned to name them. In contrast, stock pickers and political scientists who make long-term forecasts operate in a zero-validity environment. Their failures reflect the basic unpredictability of the events that they try to forecast.

Kahneman, Daniel. Thinking, Fast and Slow. New York: Farrar, Straus and Giroux, 2011.

Romney Right that Culture Matters for Economic Success


Source of book image: http://photo.goodreads.com/books/1172699090l/209176.jpg

In the piece quoted below, and in much of the TV media coverage, the story is spun as being that Romney offended the Palestinians. But that is not the story. The story is that Romney courageously highlighted an important, but politically incorrect, truth—culture, generally, does matter for economic performance; and Israeli culture, specifically, has encouraged economic growth.
Romney referred to an important book by the distinguished economic historian David Landes. Last school year, one of the students in my Economics of Technology seminar gave a presentation on a related Landes book. That presentation can be viewed at: http://www.amazon.com/review/R2GLBAMFCS5PXH/ref=cm_cr_pr_perm?ie=UTF8&ASIN=0521094186&linkCode=&nodeID=&tag=
I recently read another relevant book, Start-Up Nation, that directly supports Romney’s specific claim, by making the case that Israeli culture is especially congenial to entrepreneurial initiative and success.

(p. A1) JERUSALEM — Mitt Romney offended Palestinian leaders on Monday by suggesting that cultural differences explain why the Israelis are so much more economically successful than Palestinians, thrusting himself again into a volatile issue while on his high-profile overseas trip.
. . .
In the speech, Mr. Romney mentioned books that had influenced his thinking about nations — particularly “The Wealth and Poverty of Nations,” by David S. Landes, which, he said, argues that culture is the defining factor in determining the success of a society.
“Culture makes all the (p. A14) difference,” Mr. Romney said. “And as I come here and I look out over this city and consider the accomplishments of the people of this nation, I recognize the power of at least culture and a few other things.”
He added, “As you come here and you see the G.D.P. per capita, for instance, in Israel, which is about $21,000, and compare that with the G.D.P. per capita just across the areas managed by the Palestinian Authority, which is more like $10,000 per capita, you notice such a dramatically stark difference in economic vitality. And that is also between other countries that are near or next to each other. Chile and Ecuador, Mexico and the United States.”
The remarks, which vastly understated the disparities between the societies, drew a swift rejoinder from Palestinian leaders.

For the full story, see:
ASHLEY PARKER and RICHARD A. OPPEL Jr. “Romney Trip Raises Sparks at a 2nd Stop.” The New York Times (Tues., July 31, 2012): A1 & A14.
(Note: ellipsis added.)
(Note: the online version of the story has the date July 30, 2012.)

The Landes book discussed by Romney is:
Landes, David S. The Wealth and Poverty of Nations. New York: W.W. Norton & Company, 1998.

The book on Israeli entrepreneurship, that I mention in my comments, is:
Senor, Dan, and Saul Singer. Start-Up Nation: The Story of Israel’s Economic Miracle. hb ed. New York: Twelve, 2009.

Take U.S.D.A. and C.D.C. Advice with a Grain of Salt

(p. 8) When I spent the better part of a year researching the state of the salt science back in 1998 — already a quarter century into the eat-less-salt recommendations — journal editors and public health administrators were still remarkably candid in their assessment of how flimsy the evidence was implicating salt as the cause of hypertension.
“You can say without any shadow of a doubt,” as I was told then by Drummond Rennie, an editor for The Journal of the American Medical Association, that the authorities pushing the eat-less-salt message had “made a commitment to salt education that goes way beyond the scientific facts.”
While, back then, the evidence merely failed to demonstrate that salt was harmful, the evidence from studies published over the past two years actually suggests that restricting how much salt we eat can increase our likelihood of dying prematurely. Put simply, the possibility has been raised that if we were to eat as little salt as the U.S.D.A. and the C.D.C. recommend, we’d be harming rather than helping ourselves.
. . .
When researchers have looked at all the relevant trials and tried to make sense of them, they’ve continued to support Dr. Stamler’s “inconsistent and contradictory” assessment. Last year, two such “meta-analyses” were published by the Cochrane Collaboration, an international nonprofit organization founded to conduct unbiased reviews of medical evidence. The first of the two reviews concluded that cutting back “the amount of salt eaten reduces blood pressure, but there is insufficient evidence to confirm the predicted reductions in people dying prematurely or suffering cardiovascular disease.” The second concluded that “we do not know if low salt diets improve or worsen health outcomes.”
. . .
(p. 9) A 1972 paper in The New England Journal of Medicine reported that the less salt people ate, the higher their levels of a substance secreted by the kidneys, called renin, which set off a physiological cascade of events that seemed to end with an increased risk of heart disease. In this scenario: eat less salt, secrete more renin, get heart disease, die prematurely.
With nearly everyone focused on the supposed benefits of salt restriction, little research was done to look at the potential dangers. But four years ago, Italian researchers began publishing the results from a series of clinical trials, all of which reported that, among patients with heart failure, reducing salt consumption increased the risk of death.
Those trials have been followed by a slew of studies suggesting that reducing sodium to anything like what government policy refers to as a “safe upper limit” is likely to do more harm than good. These covered some 100,000 people in more than 30 countries and showed that salt consumption is remarkably stable among populations over time.
. . .
One could still argue that all these people should reduce their salt intake to prevent hypertension, except for the fact that four of these studies — involving Type 1 diabetics, Type 2 diabetics, healthy Europeans and patients with chronic heart failure — reported that the people eating salt at the lower limit of normal were more likely to have heart disease than those eating smack in the middle of the normal range. Effectively what the 1972 paper would have predicted.
. . .
Maybe now the prevailing beliefs should be changed. The British scientist and educator Thomas Huxley, known as Darwin’s bulldog for his advocacy of evolution, may have put it best back in 1860. “My business,” he wrote, “is to teach my aspirations to conform themselves to fact, not to try and make facts harmonize with my aspirations.”

For the full commentary, see:
GARY TAUBES. “OPINION; Salt, We Misjudged You.” The New York Times, SundayReview Section (Sun., June 3, 2012): 8-9.
(Note: ellipses added.)
(Note: the online version of the commentary has the date June 2, 2012.)