Black Swan Ideas (4)

Joe Firestone’s Blog on Knowledge and Knowledge Management


Platonic Folds, Platonicity, Randomness, Retrospective Distortion, and the Round-trip Fallacy

June 3rd, 2009

Here’s more on ideas from Nassim Nicholas Taleb’s (NNT) The Black Swan, including discussions of Platonic folds, Platonicity, randomness as incomplete information, retrospective distortion, and the round-trip fallacy.

Platonic Folds and Platonicity. NNT focuses a lot of attention on our tendency to view our concepts, models and representations as pure, sharp, crisp, abstract forms. A Platonic fold is “the place where our Platonic representation enters into contact with reality and you can see the side effects of models.” (p. 309) I think, more accurately, since we never really have such contact, it’s the place where our representations are confronted with statements or thoughts about reality which diverge from expectations we’ve developed by using the models. Platonicity, refers to our tendency to focus on our Platonic representations, “at the cost of ignoring those objects of seemingly messier and less tractable structures.” (p. 309) That is, it is our tendency to not see Platonic folds with sufficient clarity to know where it is that our models are failing us; or, in other words, to “mistake the map for the territory.”

Randomness as Incomplete Information. In another post, I pointed to NNT’s disagreement with Popper about the nature of randomness. Popper defended the view that there are random sequences. NNT defends the view that randomness is subjective; that it is just our ignorance showing. He argues (pp. 197-198) that the difference between true randomness and chaotic systems with unpredictable properties is a mathematical one; but not a practical one. People who make decisions under uncertainty understand that it all comes down to lack of knowledge anyway. In contrast, Popper developed a definition of randomness of a finite sequence that requires that it exhibits randomness from the very beginning. Thus, using his definition of randomness, his interpretation of probabilities as propensities, and his axiom system for the probability calculus, tests and refutations of the hypothesis that a sequence is random can be refuted. This allows one to say that a sequence is not random, using a limited amount of data, and to conclude that we will have a much better chance at modeling our data, if we use Mandelbrodtian models, rather than standard probability models.

Retrospective Distortion. This is the problem of explaining or relating or accounting for, “. . . or examining past events without adjusting for the forward passage of time.” (p. 310) This gives rise to the mistaken belief that these events were predictable at the time, This is an illusion, and is closely related to the narrative fallacy since it reflects our need to make sense of sequences of events after the fact.

The Round-trip Fallacy. This is the confusion of absence of evidence that unexpected, high impact events (Black Swans) have occurred, or will occur, with evidence of absence of such events (no possible Black Swans). (p. 310) For example, there is an absence of evidence, that al-Qaeda has successfully established terrorist cells in Washington, DC, at the moment. But it would be erroneous to infer that there is evidence of the absence of all such events. As NNT points out (p. 54), post- cancer treatment absence of evidence from body scans that cancer remains in the body, is not equivalent to evidence of the absence of all such cancer cells.

In this latest round of ideas from the Black Swan we see, once again, that NNT is constantly concerned with variations on the theme of confusing our models with reality, having too much faith in them, and viewing them as justified by past history, rather than as stories that may let us down at any time. His is an attempt almost to “count the ways,” in which he loves the attitude of skeptical empiricism. As a Critical Rationalist myself, I can’t help but appreciate his attempt to do this. NNT may not add much to those who have gone before him in developing this line of thought when it comes to cognitive content. But when it comes to style and driving home reasons for adhering to fallibilism and skeptical empiricism with an eye for many illustrative examples, his work is work is very rewarding. In my next KM blog, I’ll wind up my review of ideas from The Black Swan.