Diversity of Opinion

Diversity of Opinion is one of the conditions that allows a group to make sound judgments. It contributes in two related ways: it brings perspectives and possible solutions that would otherwise be absent, and it makes it easier for individuals to state what they actually think rather than conform to a group. The idea is not that every diverse group is automatically wise. Difference matters when people possess relevant information, retain some independence, and can bring their separate judgments into a collective result.

What Diversity Adds

In a large crowd, diversity helps make errors cancel out. Each person’s estimate contains both information and error; when many sufficiently diverse and independent estimates are averaged, individual errors can offset one another, leaving a collective judgment that preserves much of the information people hold. The market response to the Challenger disaster illustrates this possibility: the stock prices of Thiokol and its competitors reflected traders’ combined assessments of the companies’ losses, even if no individual trader knew for certain that Thiokol was responsible. The crowd’s judgment could be accurate because it gathered fragments of information dispersed among its members.

Aggregation alone, however, cannot supply information that no one in the group has. A crowd may average away error and still reach a poor answer if its members have little relevant knowledge. The claim for collective intelligence is therefore conditional: a group needs diversity of opinion, independence of judgment, decentralization that allows specialization and local knowledge, and a mechanism for aggregation. Diversity provides different informational starting points; independence keeps one person’s view from merely echoing another’s; aggregation makes the separate judgments usable as a whole.

The same principle applies when a group must discover possible solutions rather than choose among a known set. In markets, the alternatives may already be defined; in innovation, they must first be found. Entrepreneurs act like scouts, generating possibilities, while investors and customers help select among them. That process depends on a system willing to fund speculative ideas with slim chances of success and on diversity among both the people proposing ideas and the people controlling capital. If decision-makers resemble one another, they are more likely to favor similar proposals, narrowing the range of products and approaches that get a chance. Varied sources of funding can instead support different technological directions, as early radio’s competing funding arrangements did.

Diversity in Groups and Organizations

Markets often contain differences in risk tolerance, time horizons, investing styles, and information simply because many people can participate. A small team or formal organization cannot count on that diversity arising by itself: its members must be selected and its procedures must leave room for their distinct contributions. In a small group, a few biased or influential members can otherwise skew the result.

Experiments by political scientist Scott Page show why a group’s combined ability cannot be judged by the intelligence of its members alone. In computer simulations, groups of ten or twenty agents, each with a different set of skills, tackled a complex problem. Groups containing both highly capable and less effective agents almost always outperformed groups composed only of the strongest agents. Randomly selecting a group could do as well as or better than investing substantial effort in identifying the smartest agents and assigning them the task alone.

The result does not make intelligence irrelevant: the successful groups still included high-performing agents, and none of the simulated agents was ignorant. Rather, intelligence alone did not guarantee that a group would contain different ways of approaching a problem. If high performers share a similar set of skills, a group of them may collectively know less than a group that includes people with less ability but different skills. Diversity enlarges the group’s effective range of tools and helps it explore alternatives instead of repeatedly applying the same strengths.

James G. March’s account of organizational learning extends this argument over time. A homogeneous group can become proficient at exploiting what it already does well while growing less able to investigate alternatives, because each member contributes less new information. Bringing in people with different, even less developed, expertise can renew learning. The tradeoff is not between competence and incompetence but between reinforcing established capabilities and preserving the capacity to discover what the group does not yet know.

Independence and the Cost of Conformity

Diversity also changes the social conditions under which people speak. Homogeneous groups can become cohesive quickly; cohesion may increase members’ dependence on one another and insulate the group from outside views. In the pattern Irving Janis called groupthink, members may share an illusion of invulnerability, explain away counterarguments, and treat dissent as unhelpful. Agreement then becomes a sign of allegiance or confidence rather than evidence that the group has tested its assumptions.

The Bay of Pigs invasion shows the consequences of a decision process with too little dissent. The Kennedy administration’s planners were also asked to judge whether their own strategy would work, while skeptics were quickly silenced. The CIA’s intelligence branch and the State Department’s Cuban desk were not consulted. The resulting plan neglected basic facts about Cuba in 1961: Fidel Castro’s popularity, the strength of the Cuban army, and even the island’s size. It assumed that 1,200 men could take over the country. The failure was not simply a shortage of information; relevant perspectives were kept outside the decision-making process, and the group’s confidence went insufficiently challenged.

Solomon Asch’s line-judgment experiments demonstrate how social pressure can override an individual’s perception even when the evidence is plain. Many participants sometimes said that lines clearly shorter or longer than the comparison line were equal to it. Seventy percent changed their real opinion at least once, and a third went along with the group at least half the time. Their later explanations emphasized the desire not to stand out, not a genuine belief that the lines matched. Yet the pressure was fragile: when one confederate gave the correct answer and thereby offered the participant an ally, conformity fell sharply. A single dissenting voice could make it easier for others to speak honestly.

Diversity thus protects independence as well as adding perspectives. Its contribution is not merely a wider inventory of ideas; it reduces the social cost of expressing a minority judgment. That matters because collective judgment can use members’ private information only if they are willing to reveal it. A group may contain different knowledge in principle and still fail to benefit from it if its members hide disagreement or reshape what they know to fit the prevailing view.

Decentralized Knowledge, Shared Judgment

Decentralization makes room for specialization and local knowledge, but it does not guarantee that information discovered in one part of a system will reach the rest. Its strength is that people can work independently and draw on experience close to a problem; its weakness is that useful knowledge can remain isolated. A capable system must therefore keep local knowledge specific enough to be valuable while making it collectively available. The challenge is not to choose between decentralization and organization, but to connect distributed judgment without erasing the differences that make it informative.

The pre-September 11 intelligence community illustrates the distinction. Division of labor among agencies could support specialized analysis, and a piece of information dismissed as noise by one group might reveal a meaningful clue to another. But the agencies lacked an effective way to aggregate judgments. Databases were fragmented, information-sharing was inadequate, and, two years after the attacks, there was still no unified watch list drawing on data from across the intelligence community. Senator Richard Shelby argued that the FBI’s decentralized structure had left information in largely independent fiefdoms and favored placing one agency above the disputatious bureaucracies.

The book distinguishes sharing information from centralizing judgment. A central agency might make information easier to gather in one place, but putting a small group in charge of deciding what matters would sacrifice the diversity, local knowledge, and independence that specialization can provide. The missing ingredient was aggregation: a way to make the collective significance of information visible without requiring a single center to replace the judgments of the larger community. Linking agency databases was one practical means of improving information flow while preserving institutional autonomy.

Scientific and Corporate Practice

The international SARS investigation offers a contrasting example of distributed expertise joined by active exchange. After China reported cases in Guangdong Province in early February 2003, the World Health Organization organized eleven laboratories from around the world to investigate the disease. Beginning March 17, they held daily teleconferences, posted microscope photographs, analyses, and test results to a WHO website, and regularly exchanged virus samples. Labs could work on the same material in parallel, compare results, and eliminate possible causes together. Researchers in Hong Kong and at the U.S. Centers for Disease Control independently isolated promising viruses; laboratories in Germany, the Netherlands, and Hong Kong sequenced the coronavirus, and infection experiments in the Netherlands produced SARS-like illness in monkeys. On April 16, about a month after the collaboration began, the laboratories announced that the coronavirus caused SARS.

The first person to spot the coronavirus was electron microscopist Cynthia Goldsmith, but identifying a candidate was not the same as proving that it caused the disease. That conclusion depended on the work of laboratories that tested samples, compared findings, and ruled out alternatives. The discovery was collective, not an individual achievement enlarged after the fact. Although the WHO convened the network, it did not dictate each laboratory’s research assignments or direct the exchange of information. The labs agreed to share relevant data and meet every morning, then worked out how to divide the investigation. Their different capabilities and overlapping checks made the collaboration faster and more effective than isolated work would have been.

Scientific diversity depends on more than assembling collaborators for a single project. Open exchange allows other researchers to inspect published results, challenge conclusions, and build new hypotheses from shared data. Failed hypotheses contribute too, by showing colleagues where not to look. Scientific knowledge is therefore collective not only because it accumulates across generations, but because contemporaries depend on one another’s work. Keeping information available to others turns individual discoveries, including negative results, into resources for a wider community.

In corporations, by contrast, formal hierarchy can make a group less able to use the knowledge it already possesses. At Ford, more than fifteen managerial layers separated the chairman from a factory-floor supervisor, compared with five at Toyota. In one General Motors plant in Van Nuys, a worker who had installed a bracket for two years did not know it held the car’s sunshade. The episode makes organizational distance concrete: a worker can repeatedly perform a task without being given information about its purpose, while managers far from production may lack a reliable picture of how the work is actually done. One company chart showed that a new product idea had to pass through 223 possible bureaucratic paths before approval.

Local authority can help counter that distance. Decisions about local problems are often best made by people close to them, whose experience supplies tacit knowledge that is difficult to transmit up and down a hierarchy. In the Toyota Production System, frontline workers learn a broad range of skills and how the production process works as a whole; teams take responsibility for their own work rather than leaving each worker isolated at a narrow task. Any worker can pull a cord to stop the line when something needs fixing. The cord is rarely pulled, but its availability gives workers both a real channel for intervention and a reason to take responsibility for the process.

Across these examples, diversity is not a decorative virtue or a demand that every decision be made by consensus. It is a practical condition for discovering alternatives, correcting errors, and making dispersed knowledge usable. Groups become smarter when they preserve differences long enough for those differences to inform a shared judgment; they become less capable when conformity, hierarchy, or fragmented communication turns many potential perspectives into a single untested view.