Interpersonal trust is a fundamental aspect of our society that is essential for liberty, prosperity and the smooth operation of all aspects of life. It simply costs more in terms of time, effort, emotion and money if we have to protect our interactions against betrayal.
Sociologists and psychologists (and those in between) study trust, and have found some disturbing things. The World Values Survey (www.worldvaluessurvey.org) has been measuring interpersonal trust since 1981, and finds that trust in the United States is in decline. Other surveys have found similar results. (See .) WVS itself puts current (2015) US interpersonal trust levels in the upper 30’s.
This trend is not surprising, given all that is going on, culturally speaking, in the US:
Unfortunately, cultural diversity seems to work against trust. From Jonathan Haidt (here) “A recent study by Robert Putnam (titled E Pluribus Unum) found that ethnic diversity increases anomie and social isolation by decreasing people’s sense of belonging to a shared community.” People simply need a certain amount of cultural (and hence moral) homogeneity to feel that they can trust others. To state it the other way around, greater cultural and moral diversity makes it harder for people to predict what others will do, which is the essence of trust.
Of course when anyone suggests that cultural diversity might have a downside, there will be pushback. In particular, it will be tempting to look more deeply at the World Values Survey to find other nations with greater cultural diversity than the US, yet where interpersonal trust is higher. But I would caution the reader that—despite what WVS may claim—it is not valid to compare trust levels across national or linguistic boundaries. (See here for the reasoning, which would also apply to questions of trust.) The same survey question, sincerely translated into another language or asked in another nation, will not have exactly the same meaning, no matter how diligent one is. And cultural expectations of how one “should” answer the question will also vary from place to place. Therefore, the only valid use of such trend numbers is comparing them over time within a single nation.
The increasing amount of information we have about each other also seems to degrade trust. The internet, which was supposed to smooth cultural differences and promote understanding, is actually doing the opposite. (See here and .)
Higher divorce rates, and the fragility of our relationships in general, give us less experience with trusting relationships. To avoid being repeatedly hurt, we insulate ourselves, which means being less trusting as time goes on.
Lastly, we are clearly in a time of extremely rapid social change—as are most prosperous nations (see here). This makes it difficult for older generations to trust the younger, because it is difficult to see what boundaries the young won’t cross. Younger generations likewise cannot relate to the old.
Sadly, we should expect levels of trust to slip further, as none of the above trends are showing any signs of reversing.
 The declining trust graphic is from “Trust in people over time: Interpersonal trust among US public, 1960–1995”; 1960 data from Civic Culture Survey; 1962-1994 data from National Election Surveys and General Social Surveys, 1995 data from WVS. This is from the chapter entitled “Trust, Well-Being and Democracy” by Ronald Inglehart, which appears in Democracy and Trust, edited by Mark E. Warren.
 “Less Is More: The Lure of Ambiguity, or Why Familiarity Breeds Contempt”, Norton, Michael I., Frost, Jeana H., and Dan Ariely, Journal of Personality and Social Psychology 2007, Vol. 92, No. 1, 97-105.