Spot the Phony: Uncertainty Principle Misuse
Taleb warns against invoking Heisenberg’s uncertainty principle as an explanation for limits of prediction in economics or politics. A scientific analogy needs a relevant mechanism; citing quantum physics does not establish one.
THE IDEA
The uncertainty principle states that in quantum physics, one cannot measure certain pairs of values (with arbitrary precision), such as the position and momentum of particles. You will hit a lower bound of measurement: what you gain in the precision of one, you lose in the other. So there is an incompressible uncertainty that, in theory, will defy science and forever remain an uncertainty. This minimum uncertainty was discovered by Werner Heisenberg in 1927. I find it ludicrous to present the uncertainty principle as having anything to do with uncertainty. Why? First, this uncertainty is Gaussian. On average, it will disappear—recall that no one person’s weight will significantly change the total weight of a thousand people. We may always remain uncertain about the future positions of small particles, but these uncertainties are very small and very numerous, and they average out—for Pluto’s sake, they average out! They obey the law of large numbers we discussed in Chapter 15. Most other types of randomness do not average out! If there is one thing on this planet that is not so uncertain, it is the behavior of a collection of subatomic particles! Why? Because, as I have said earlier, when you look at an object, composed of a collection of particles, the fluctuations of the particles tend to balance out.
But political, social, and weather events do not have this handy property, and we patently cannot predict them, so when you hear “experts” presenting the problems of uncertainty in terms of subatomic particles, odds are that the expert is a phony. As a matter of fact, this may be the best way to spot a phony.
I often hear people say, “Of course there are limits to our knowledge,” then invoke the uncertainty principle as they try to explain that “we cannot model everything”—I have heard such types as the economist Myron Scholes say this at conferences. But I am sitting here in New York, in August 2006, trying to go to my ancestral village of Amioun, Lebanon. Beirut’s airport is closed owing to the conflict between Israel and the Shiite militia Hezbollah. There is no published airline schedule that will inform me when the war will end, if it ends. I can’t figure out if my house will be standing, if Amioun will still be on the map—recall that the family house was destroyed once before. I can’t figure out whether the war is going to degenerate into something even more severe. Looking into the outcome of the war, with all my relatives, friends, and property exposed to it, I face true limits of knowledge. Can someone explain to me why I should care about subatomic particles that, anyway, converge to a Gaussian? People can’t predict how long they will be happy with recently acquired objects, how long their marriages will last, how their new jobs will turn out, yet it’s subatomic particles that they cite as “limits of prediction.” They’re ignoring a mammoth standing in front of them in favor of matter even a microscope would not allow them to see.
When to use it
Listening to an economist or pundit justify their predictions by referencing quantum physics—use this heuristic to identify a potential phony.
Evaluating experts who claim that because of the uncertainty principle, we cannot predict anything—recognize the misapplication.
In risk analysis, examine tail behavior and dependence before assuming that individual uncertainties will cancel in aggregate.
When advising a leader facing high-stakes uncertainty, caution against metaphors from quantum mechanics that trivialize real-world unpredictability.
FROM THEORY TO EVERYDAY LIFE
In practice
The Lebanon Conflict Example
In August 2006, the author, trying to travel to his ancestral village of Amioun, Lebanon, faced the closure of Beirut's airport due to the Israel-Hezbollah conflict. He could not predict when the war would end, whether his house would be standing, or if the conflict would escalate. Taleb uses this experience to challenge the relevance of a quantum-physics analogy to uncertainty about a war.
Myron Scholes Invoking Quantum Physics
The author recalls hearing economist Myron Scholes at conferences say 'of course there are limits to our knowledge' and then invoke the uncertainty principle to justify that 'we cannot model everything.' This is presented as a classic phony move.
A MOMENT TO REFLECT
Put it to work.
When have you heard someone invoke a scientific principle to explain uncertainty in everyday life? How did it feel?
Why is it fallacious to apply Heisenberg's uncertainty principle to social, political, or economic events?
What features of a model determine whether combining observations reduces uncertainty? When might dependence or extreme outcomes limit that benefit?
CONTINUE THE CONVERSATION
Source texts
- The Black Swan The Impact of the Highly Improbable With a new section On Robustness and Fragility (Nassim Nicholas Taleb)