Psychologist; Director of the Center for Adaptive Behavior and Cognition at the Max Planck Institute for Human Development in Berlin; Author, Risk Savvy
Deliberate Ignorance

Ignorance is generally pictured as an unwanted state of mind, and the notion of deliberate ignorance may raise eyebrows. Yet people often choose to be ignorant, demonstrating a form of negative curiosity at odds with concepts such as ambiguity aversion, a general need for certainty, and the Bayesian principle of total evidence. Such behavior also contrasts with the standard belief that more knowledge and data are always preferred, expressed in various forms from Aristotle (“All men by nature desire to know”) to the view of humans as informavores to the mission of national surveillance programs.

Deliberate ignorance can be defined as the willful decision not to know the answer to a question of personal interest, even if the answer is free, that is, with no search costs. The concept differs from the study of agnotology or the sociology of ignorance, which investigates the systematic production of ignorance by deflecting, covering up, and obscuring knowledge, such as the tobacco industry’s efforts to keep people unaware of the evidence that smoking causes cancer. Deliberate ignorance, in contrast, is not inflicted by third parties but self-chosen. Yet why would people not want to know? The few existing studies and even fewer explanations suggest at least four motives.

The first is to avoid potentially bad news, particularly if no cure or other prevention is available. According to Greek mythology, Apollo granted Cassandra the power of foreseeing the future but added a curse that her prophecies would never be believed. Cassandra foresaw the fall of Troy, the death of her father, and her own murder; anticipating the approach of future horrors became a source of endless pain. Technological progress steadily shifts the line between what we cannot and what we can know in the direction of Cassandra’s powers. When having his full genome sequenced, James Watson, the co-discoverer of DNA, stipulated that his ApoE4 genotype, which indicates risk of Alzheimer’s disease, be both kept from him and deleted from his published genome sequence. Researchers claim to have discovered biomarkers that predict when a person will likely die and from what cause, while others claim to be able to predict whether a marriage will end in divorce. But do you want to know the date of your death? Or whether you should soon consult a divorce lawyer? The few available studies indicate that 85-90% of the general public do not want to know the details surrounding their death and marital stability. Yet unlike the curse condemning Cassandra to foresee the future, technological progress means that we will increasingly often have to decide how much foresight we want.

The second motive is to maintain surprise and suspense. Depending on the country, some 30-40% of parents do not want to know the sex of their unborn child, even after prenatal ultrasound or amniocentesis. For these parents, knowing the answer would destroy their pleasurable feeling of being surprised, a feeling that appears to outweigh the benefit of knowing and being able to better plan ahead.

A third motive is to profit strategically from remaining ignorant, as proposed by economist Thomas Schelling in the 1950s. The game of chicken is an example: people walking through the street staring at their smartphones and ignoring the possibility of a collision, thereby forcing others to do the work of paying attention. Similarly, it has been argued that since the crisis of 2008, bankers and policymakers strategically display blindness in order to ignore the risks in which they continue to engage and to stall effective reform.

Finally, deliberate ignorance is used as a tool for achieving fairness and impartiality. In keeping with Lady Justice, who is often depicted as wearing a blindfold, many U.S. courts do not admit evidence about a defendant’s criminal record. The idea is that the jury should remain ignorant about previous crimes in order to reach an impartial verdict. Rawls’ “veil of ignorance” is another form of ignorance in service of fairness.

Despite these insights, however, the phenomenon of deliberate ignorance has been largely treated as an oddity. Science and science fiction celebrate the value of prediction and total knowledge through Big Data analytics, precision medicine, and surveillance programs largely unquestioned. However, as for Cassandra, foreknowledge may not suit every person’s emotional fabric. How we decide between wanting and not wanting to know is a topic that calls for more scientific attention and greater curiosity.