In recent years, Putnam has been engaged in a comprehensive study of the relationship between trust within communities and their ethnic diversity. His conclusion based on over 40 cases and 30 000 people within the United States is that, other things being equal, more diversity in a community has a correlation [expressed as a beta equal to 0.04 in a multiple regression analysis (see Putnam, 2007), to less trust both between and within ethnic groups. Although only a single study and limited to American data, it claims to put into question both contract theory and conflict theory in inter-ethnic relations. According to conflict theory, distrust between the ethnic groups will rise with diversity, but
not within a group. According to contact theory, distrust will decline as members of different ethnic groups get to know and interact with each other. Putnam describes people of all races, sex and ages as "hunkering down" and going into their shells like a turtle. For example, he did not find any significant difference between 90 year olds and 30 year olds.
Low trust with high diversity not only affects ethnic groups, but is also associated with:
- Lower confidence in local government, local leaders and the local news media.
- Lower political efficacy — that is, confidence in one's own influence.
- Lower frequency of registering to vote, but more interest and knowledge about politics and more participation in protest marches and social reform groups.
- Less expectation that others will cooperate to solve dilemmas of collective action (e.g., voluntary conservation to ease a water or energy shortage).
- Less likelihood of working on a community project.
- Less likelihood of giving to charity or volunteering.
- Fewer close friends and confidants.
- Less happiness and lower perceived quality of life.
- More time spent watching television and more agreement that "television is my most important form of entertainment".
Putnam published his data set from this study in 2001 [1] [2] and subsequently published the full paper in 2007.
Putnam has been criticized for the lag between his initial study and his publication of his article. In 2006, Putnam was quoted in the
Financial Times as saying he had delayed publishing the article until he could "develop proposals to compensate for the negative effects of diversity" (quote from John Lloyd of Financial Times) [3]. In 2007, writing in
City Journal, John Leo questioned whether this suppression of publication was ethical behavior for a scholar, noting that "Academics aren’t supposed to withhold negative data until they can suggest antidotes to their findings." [4] On the other hand, Putnam did release the data in 2001 and publicized this fact [5]. The proposals that the paper contains are located in a section called "Becoming Comfortable with Diversity" at the end of his article. This section has been criticized for lacking the rigor of the preceding sections. According to Ilana Mercer "Putnam concludes the gloomy facts with a stern pep talk". [6]