When social scientists talk about the consequences of communication across lines of difference, what they generally have in mind are the potential benefits that may accrue from face-to-face interactions of this kind, the very kind outlined in the previous chapter. Or perhaps they are concerned with the potential dangers posed by a lack of political diversity in people's social environments. In either case, social integration is seen as a public good, whereas segregation is inherently bad; heterogeneous environments are perceived to be ideal for promoting democratic ends, and homogeneous ones are considered undesirable.

And yet, when broadly considered, plenty of evidence points to the potential for negative outcomes as a result of communication across lines of political difference. Most often, this evidence is taken from studies of small groups in which polarization results from bringing those of opposing views together for discussion. If cross-cutting contact produces defensiveness or causes people to dig in their heels and counterargue, they may become all that much more strongly committed to their original positions, thus making further conversation and compromise even more difficult. This same “dark side” has been noted in considerations of the supposed benefits of “deliberation” variously defined. Still other scholars note that violence can and sometimes does erupt when those of differing views come into close contact. The threat of a violent outcome is particularly great when those who have been living in segregated settings are first exposed to those of differing views.