They refuse to recognise discontinuities, paradigm shifts, or regime changes. We must have trends, norms, averages, and other indicators of central tendency before we can have what we perceive as shocks to the system. But the Darwinian would argue that diversity in nature is so great and every event could lead to such a great variety of outcomes, that there is no such thing as a state of nature that we can identify as a paradigm. The trick in risk management, perhaps, is in recognising that normal is not a state of nature but a state of transition and trend is not destiny. Yet Gould is sending us a positive message.
Variety is the spice of life.
It means that we have more than one basket in which to deposit the eggs we want to carry. As a result, society is willing to take on more risk than if we had just one basket. Indeed, variety is at the essence of survival. We do not all come down with mesothelioma at the same instant, all ships do not sink together, all houses do not burn up simultaneously, all stocks do not go up and down in lockstep together, and different capital assets have different cyclical patterns. The philosophical issue runs even deeper.