Scientists distinguish between two types of potential errors in their research. Type I errors occur when something seems true but, in fact, isn't. Type II errors are the opposite: the scientist mistakenly rejects what is correct. In the first, overzealousness triumphs - while premature skepticism wins in the second. The first exaggerates the evidence; the second disregards it.
Medicine poses a similar set of even riskier alternatives. Physicians distinguish between false positives - where an incorrect diagnosis is made - versus a false negative - where the correct diagnosis is overlooked. The first over-detects; the latter under-detects.
In both science and medicine, there is a tension between seeing what isn't there versus overlooking what is. Wisdom is weighing the willingness to seek conclusiveness with a healthy dose of caution.
A similar set of alternatives exist in everyday ethics and public policy - but these are rooted much more in moral judgement. We often find ourselves weighing the needs of the community against the rights of the individual. Should danger be reduced at any price? This risks false positives - overstating the risks and trampling on the rights of the innocent. Or should freedom be protected at an unknown cost to society's well-being? This risks false negatives - underestimating the threat to the public.
Our justice system is based on balancing the two competing tendencies of protecting public safety and preserving personal liberty. Should actions favor Type I errors (by foreseeing dangers that might not materialize) or Type II errors (by valuing personal rights at the expense of potential harm to others)?
At times, this tips more one way than another. Mass incarceration is a glaring example of erring on the side of keeping the convicted off the streets, whether they remain a danger or not. Racial profiling plays the odds of catching more criminals, even if this vilifies innocent members of a minority. Extreme interrogation techniques value unearthing the truth over treating others humanely. Video and computer surveillance puts the protection of society over invasion of privacy. Threatening to close the borders to Moslems aims to keep terrorists out, while denying human rights and dignity to far more who will never cause any harm. All flagrant false positives, all restrictive of the personal freedom of some, and all committed in the name of protecting the community at large from imminent dangers.
But false negatives have their detractors as well. Very real physical injury can occur when rights are given priority over safety. Unlike in science and medicine, this balance cannot be objectively forecasted or calibrated. These choices defy quantification - and stir emotion. If blocking all Muslims from entry to America eliminates a few acts of terrorism, or lengthy mandatory sentences keeps some future crimes from being committed, or monitoring the public uncovers some criminals, does that justify these policies? How can the potential benefit of these measures be weighed against their intangible cost to personal freedom?
The risks of erring too much on one side or the other always looms. These choices are often made on conjecture - not science - and grounded in personal biases about protecting safety and freedom. And these biases are fueled by fears, not statistics. We react to events and anecdotes, not probabilities, and act on conclusions based on these anxieties of what might happen in the future.
American history is littered with now embarrassing Type I errors: the Alien and Sedition Acts of 1798, Lincoln's wish to waive the writ of habeas corpus, the detention of Japanese Americans during the Second World War, and McCarthyism. All sacrificed personal liberty for an almost paranoid fear of threats. These concessions to public hysteria marred the legacy of otherwise great presidential leadership.
Are we entering a new and dangerous era of willfully suspending freedom for security? Will future generations look back critically at the Type I errors and false positives of our times? Not surprisingly, both the American Civil Liberties Union and Planned Parenthood received unprecedented donations after the recent presidential election - to fortify an ethical stance that favors individual rights.
The pendulum of competing alternatives needs to achieve equilibrium. We need to guard against the exaggerations, emotions, and myopia that periodically grip a nation, which then give way to demagoguery and simplistic solutions. We need to prepare ourselves for the ride we are about to take in the Age of Trump. These times call for a moderate and even courageous center engaged in the often delicate and difficult task of balancing the needs of the community against the rights of the individual.
Jay A. Halfond is Professor of the Practice at Boston University and a Research Fellow at Bentley University's Center for Business Ethics.