8
$\begingroup$

So Taleb has two heuristics to generally describe data distributions. One is Mediocristan, which basically means things that are on a Gaussian distribution such as height and/or weight of people.

The other is called Extremistan, which describes a more Pareto like or fat-tailed distribution. An example is wealth distribution, 1% of people own 50% of the wealth or something close to that and so predictability from limited data sets is much harder or even impossible. This is because you can add a single sample to your data set and the consequences are so large that it breaks the model, or has an effect so large that it cancels out any of the benefits from prior accurate predictions. In fact this is how he claims to have made money in the stock market, because everyone else was using bad, Gaussian distribution models to predict the market, which actually would work for a short period of time but when things went wrong, they went really wrong which would cause you to have net losses in the market.

I found this video of Taleb being asked about AI. His claim is that A.I. doesn't work (as well) for things that fall into extremistan.

Is he right? Will some things just be inherently unpredictable even with A.I.?

Here is the video I am referring to https://youtu.be/B2-QCv-hChY?t=43m08s

$\endgroup$
6
$\begingroup$

Yes and no!

There's no inherent reason that machine learning systems can't deal with extreme events. As a simple version, you can learn the parameters of a Weibull distribution, or another extreme value model, from data.

The bigger issue is with known-unknowns vs. unknown-unknowns. If you know that rare events are possible (as with, say, earthquake prediction), you can incorporate that knowledge into the models you develop, and you'll get something that works as well or better than humans in that domain. If you don't know that rare events are possible (as with, say, a stock market crash produced by correlated housing defaults), then your model will reflect that as well.

I tend to think Taleb is being a bit unfair here: AI can't handle these kinds of events precisely because its creators (us) can't handle them! If we knew they were possible, then we could handle them pretty well, and AI could too.

$\endgroup$
  • 1
    $\begingroup$ Isn't the inability of these models (including human ones in the brain) to handle unknown-unknowns kind of his point? Since there is always a limit to the amount of accurate data we can gather in our samples and in instances of fat-tail distributions the effect of an outlier can be huge, whereas in a normal distribution the effect or damage of an extreme outlier will usually be pretty small. So it's as if he is saying this is a fundamental characteristic to knowledge and predictive systems, biological or machine based, hence why A.I. will be limited in certain domains. $\endgroup$ – Josiah Swaim Aug 16 '18 at 19:22
  • 2
    $\begingroup$ Hmm. I think there are two issues. One is the claim that we can't handle fat-tailed distributions with AI. This is false. The other is that, if you don't know what distributions are suited to the problem you're studying (that is, if you don't really understand your problem), then you'll be surprised by unexpected events. This is true. I think Taleb is conflating the two issues, when really they are separate. $\endgroup$ – John Doucette Aug 16 '18 at 20:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.