Silent Evidence
The concept that our observations and inferences are systematically distorted by the absence of data from unobserved or unrecorded cases, leading to overestimation of certain phenomena and underestimation of fragility.
THE IDEA
More Hidden Applications
Silent evidence consists of cases absent from the record we use to draw conclusions. Extinctions and undetected crimes illustrate how that absence can shape an inference.
The stability of species. Take the number of species that we now consider extinct. For a long time scientists took the number of such species as that implied from an analysis of the extant fossils. But this number ignores the silent cemetery of species that came and left without leaving traces in the form of fossils; the fossils that we have managed to find correspond to a smaller proportion of all species that came and disappeared. This implies that our biodiversity was far greater than it seemed at first examination. A more worrisome consequence is that the rate of extinction of species may be far greater than we think—close to 99.5 percent of species that transited through earth are now extinct, a number that scientists have kept raising through time. Life is a great deal more fragile than we have allowed for. But this does not mean we (humans) should feel guilty for extinctions around us; nor does it mean that we should act to stop them—species were coming and going before we started messing up the environment. There is no need to feel moral responsibility for every endangered species.
Does crime pay? Newspapers report on the criminals who get caught. There is no section in The New York Times recording the stories of those who committed crimes but have not been caught. So it is with cases of tax evasion, government bribes, prostitution rings, poisoning of wealthy spouses (with substances that do not have a name and cannot be detected), and drug trafficking.
In addition, our representation of the standard criminal might be based on the properties of those less intelligent ones who were caught.
Once we seep ourselves into the notion of silent evidence, so many things around us that were previously hidden start manifesting themselves. Having spent a couple of decades in this mind-set, I am convinced (but cannot prove) that training and education can help us avoid its pitfalls.
When to use it
Evaluating business success stories by considering the far more numerous failed companies that are not publicized.
Assessing crime rates based on reported crimes versus actual crimes, accounting for unreported incidents.
Interpreting historical events by factoring in perspectives from those who did not leave written records.
Understanding species extinction rates by acknowledging the vast number of unrecorded extinctions.
FROM THEORY TO EVERYDAY LIFE
In practice
The stability of species
Taleb argues that the fossil record omits species that left no discoverable traces. He cites 99.5% as the proportion of all species that have become extinct. That is a cumulative fraction, not an extinction rate measured over a particular interval.
Does crime pay?
Taleb points out that stories of caught criminals omit crimes that remain undetected. Inferring the traits or success of all offenders from those who were caught can therefore produce a biased picture.
A MOMENT TO REFLECT
Put it to work.
What silent evidence might be missing from your current analysis or decision-making process?
How does the absence of data on failed attempts skew your perception of success in a given domain?
In what ways might your personal experiences or observations be shaped by overlooking silent evidence?
CONTINUE THE CONVERSATION
Source texts
- The Black Swan The Impact of the Highly Improbable With a new section On Robustness and Fragility (Nassim Nicholas Taleb)