Nassim Taleb : Convexity, Robustness, and Model Error inside the Fourth Quadrant,

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Excerpts from Nassim Taleb's lecture OxfordBTLecture
The central idea in The Black Swan is about the limits in the knowledge about of small probabilities, both empirically (interpolation) and mathematically (extrapolation)2, and its consequence. This discussion starts from the basis of the isolation of the "Black Swan domain", called the "Fourth Quadrant"3, a domain in
which 1) there is dependence on small probability events, and 2) the incidence of these events is incomputable. The Fourth Quadrant paper cursorily mentioned that there were two types of exposures, convex and concave and that we need to "robustify"4 though convexification. This discusses revolves around convexity biases as explaining the one-way failure of quantitative methods in social science (one-way in the sense that quantitative models in social science are worst than random: their errors go in one direction as they tends to fragilize).