In the last post (Games 3), we looked at how people may be confused by volatility.
You might think that people who look at financial markets would not be so easily confused.
A great example of such a confusion comes from Nassim Taleb’s bestselling book “Fooled by Randomness”. I would possibly suggest the author has been “Fooled by Volatility”!
Here is my summary of the argument of the book, with my comments on it below:
1. Events have some randomness associated to them
Hardly rocket science, but an underappreciated point.
2. Humans are poor at understanding randomness, overemphasizing the importance of small amounts of evidence (often outliers)
You can find similar argument in many other books (Gladwell), but useful to highlight and he provides decent examples from finance.
3. People trading the market often assign their success to skill whereas they are just lucky
This is certainly at least partially true – some rich people are just lucky and are not smarter.
I think there is a legitimate debate on the degree to which the overall statement is true
4. All trading success is down to luck
Therefore success is evidence of luck
This is a logic error. By appealing to the emotions and prejudices of the reader, some may not spot it. The book leaves the impression that all successful traders are just lucky.
Confused by volatility
The source of the error seems to be a conceptual confusion between volatility and randomness. The author observes that outcomes have volatility but names it randomness, since it is “random” this implies there must be no skill. This is exactly the mistake I described in the last post.
It is a shame because some of the underlying arguments (see above) are interesting and true. The fact that outcomes are only partially determined by merit and that people incorrectly over-attribute success to ability is often overlooked.
For a rather extreme example, apparently even Trump’s son-in-law Kushner believes he owes his position purely to merit despite inheriting a huge fortune, reportedly having his place at Harvard bought for him and then marrying the daughter of a billionaire who becomes President.
The rest of the book
For completeness, some notes on the rest of the book:
5. Traders make money by selling tail risks. They all blow up in the end
The assumption that this is the only form of trading that exists is ludicrous.
Again, appealing to the prejudices of a certain kind of reader, it implies successful traders aren’t just lucky, they are dangerous.
6. Traders who consistently buying tail risks are the only ones that understand probability, but may appear that they have low skill given their average performance.
Here the suggestion is that consistently poor investment results are an indication of integrity and intelligence, which is again ridiculous. Another emotional argument to make people feel better about not being able to replicate the success of others.
See my thoughts on the link between desire and belief here (Desire – The Fatal Flaw).
7. Everyone else who makes money is just lucky, but Taleb can make money by being skillful
Here the suggestion is Taleb is a unique genius
It is a real pity that the arguments in this book are taken to an illogical extreme, but perhaps this is key to explain the popularity of the book. The points made in the first half of the book are significant and well explained (although not unique to Taleb).
I would have preferred if he had gone on to discuss how to spot the difference between skill and luck; or possibly how to avoid incentivising tail sell behaviour in financial markets.
Instead I read it as some kind of personal therapy about his career angst.
It reminds of a lovely quote – “all autobiography is a form of revenge”.
 As an aside Nocturnal Animals is a great movie on this theme.