On black swans

I've just finished reading Nassim Taleb's book on Black Swans.  Black swans being unpredicted and unpredictable events with a big impact.   Very interesting, and worthwhile reading.  He makes a number of important points, the net effect of which is to point out the inadequacy of most of the ways we predict real world events, or estimate their chances of happening.

One of the points he makes I find interesting, is the asymmetry in rewards for those who anticipate (and forestall) "black swan" events vs those who deal with them.  The hypothetical politician who proposed, and succeeded in getting installed before 9/11, locked and bullet-proof doors fitted between the cockpit and passenger cabins in commercial aircraft got nothing but complaints.  The heros were the people who dealt with the mess after the event.

But a  glaring error still annoys me.  He states (the quote might not be exact) "the existence of a black swan proves that all swans are not white"  No, no no.  The existence of a black swan proves that not all swans are white.  This is sloppy use of English; we know what he means but it's not what he said.

Consider:
Here is a green swan.  It is not white
Here is a purple swan.  It is not white.
Here is a yellow swan.  It is not white.
Here is a black swan.  Therefore all swans are not white.

It's a good book anyway.   Apart from that.

Book cover picture from Amazon.