Timur Kuran wrote Private Truths, Public Lies: The Social Consequences of Preference Falsification with the thesis that a significant number of people frequently lie concerning their beliefs and that these lies have dramatic social effects. Although Kuran is an economist, he draws from sociology, psychology, religion, and other fields in this book.

Kuran begins his book with an illustration of a man at his employer's dinner party. Though the man dislikes the homes décor and the meal served, the man feels compelled to offer false compliments. At the end of the evening, the man kindly says he enjoyed the evening, though he is really happy to be leaving. The fictional person is constrained from being honest by societal pressure and personal fears. Whenever people choose to lie about their true beliefs, Kuran calls that "preference falsification."

Situations such as the dinner party do occur often in people's lives. When someone at work begins to express certain political views that the listener disagrees with, the listener must decide whether to respond with the truth, or to simply take another course. The listener might simply ignore the issue, or the listener might even nod in agreement. But, how does someone make the decision of what course to take?

Kuran theorizes that people evaluate their choices based on three utilitarian factors. There is a reputational utility, an expressive utility, and an intrinsic utility. The reputational utility is the amount a certain answer will raise or lower the listener's standing in the community. Expressive utility is the value in letting others know how one truly feels. The intrinsic utility is the degree to which an option fulfills the individual's greatest good.

When people are faced with the decision of how to respond to someone they disagree with, they evaluate the different utilities. As an economist, Kuran has created various graphical functions to depict the value of each utility.

The book is more interesting, though, when Kuran turns to the sociological and psychological effects of preference falsification. Kuran points out on page 33 that numerous psychologists, such as Freud and Maslow, have shown that humans have a legitimate need to be honest about themselves. Preference falsification has negative psychological effects.

Kuran discusses some religious views on preference falsification. Both Judaism and Islam have doctrines that allow for people to publicly deny their religious faith during times of persecution. However, the faithful were expected to maintain as much of their religious practice as possible while in private. During the Protestant Reformation, Catholics debated the principle of pretending to be Protestant while hiding one's Catholicism. The Church's official stand, though, was always to reject such practice (pp. 6-7). According to the Bible, Jesus said, ""Whoever acknowledges me before men, I will also acknowledge him before my Father in heaven. But whoever disowns me before men, I will disown him before my Father in heaven" (Mt. 10:32-33 NIV). Kuran notes that whenever people have tried to maintain a secret religion, they have usually abandon their faith entirely in due time (p. 7). Psychologically, it is difficult to maintain inner belief while publicly denouncing that belief.

There are serious social effects of preference falsification also. Kuran uses communism as an example of a time when the majority believed differently than their public personas led others to believe. The result was that social change was stifled for decades. When a trigger finally made people feel comfortable in publicizing their beliefs, communism quickly fell. Affirmative action is another issue, according to Kuran, where public personas are often different than private. Anonymous polls routinely show that most Americans are against affirmative action. Yet, the practice persists because few people are willing to endure the horrendous social attacks from the minority who demands the programs. People like Jesse Jackson quickly label as racist those who oppose affirmative action. Recently, the new president of Harvard University found himself in a heated public relations battle. One of the chief complaints against the president was that upon entering office, he did not immediately release a statement praising affirmative action policies. Suddenly, even silence was enough to be branded racist. Kuran notes that the tremendous amount of resources spent defending against claims of racism leads many reasonable people to simply support affirmative action in public.

Because so many people are unwilling to take positions seen as unpopular, there is a role for activism. Kuran states that activists are people who are willing to go against the prevailing norms. Their expressive or intrinsic utilities are enough to allow them to endure social stigma, loss of jobs, and other attacks. Activists make people aware of alternative views. Sometimes, activists create an environment where being honest becomes safer. And activists can actually lead people to change their minds on issues, possibly leading to social change.

Kuran writes that there is a possible benefit to preference falsification, though. People trying to homogenize can increase institutional stability. A society where everyone is completely honest about their views would probably splinter into factions rather quickly. While preference falsification can stagnate society, it can also maintain the peace.

Private Truths, Public Lies details extensively the prevalence of preference falsification. Kuran deals with both the negative and positive aspects of the issue. His book gives the reader much to think about. Understanding Private Truth, Public Lies can help one understand how people act in public and how those public behaviors affect society.