Ideology and Homophily

Written by: Corey Washington

Primary Source: Zero Ideology

The Phenomenon

Homophily (“love of similar”), the tendency to bond with others who are similar to oneself, has been in the news lately.  Clarity Campaigns, a Democratic analytics firm, created an ideological dashboard for the Washington Post. Type in the answer to 7 simple questions, and it will give you the zip code where you can live while minimizing your risk of running into people who have views on politics that differ from your own.  If you are an environmentally oriented conservative in Michigan, Livonia, is the safest place for you. A down the line urban liberal living in New York State, you’re out of danger (not surprisingly) on the Upper West side of Manhattan.

The Pure Liberal Seeking the Same in New York State

People have been aware of our homophilous tendencies for millenia. Plato noticed it when he wrote that “similarity begets friendship” (Phaedras). Aristotle too: people “love those who are like themselves” (Nichomachian Ethics). Humans preferentially sort according to age, sex, race/ethnicity, education, intelligence, values, attitudes, aspirations, and status. Homophily is utterly natural, almost certainly part of our genetic make up, and as noted in a previous post, studies show that it is a tendency we share with our closest relatives, the chimpanzees, along with other animals.
The unprecedented quantity of data available now yields a clearer picture of how it does, and does not, dominate our lives. recently ran a story arguing that “In the End, People May Really Just Want to Date Themselves” based on an analysis of 1 million matches by made by eHarmony. They found that people on the site express a preference for partners with whom they share many characteristics, including religion and ideology. Indeed, the site builds this bias into their algorithms.


The fivethirtyeight broke down the general homophilic generalization into principles that apply to two classes of traits.



Intelligence as a preference for women follows the first pattern. Women who describe themselves as intelligent prefer men who are intelligent and women who do not describe themselves as intelligent do not express a preference for intelligent men. Intelligence for men follows the second pattern. All men say they want intelligent women, but men who describe themselves as intelligent express a stronger preference for intelligent women. (Kind of goes against the stereotype, huh?)

Not everyone wants to associate with, and live primarily around, people who share their beliefs, but a lot of us do. A recent Pew Center study on political polarization suggests people with more extreme views have a stronger preference for ideologically sympathetic and homogenous communities and friendship networks than do centrists.

This study did not investigate the direction of causation. So it is not clear whether preferring to live in homogenous communities and ideologically similar friends lead to more extreme views or whether people with more extreme views simply find diverse opinions and neighborhoods less pleasant than do moderates or whether some combination of both is true or neither.

The Consequences

Some of the causes of homophily are plain. We may bond with those like ourselves because we enjoy similar pastimes or because we find the same kinds of jokes funny or for myraid other reasons.

In recent decades, studies have come to focus on homophily’s consequences.  One could be the maintenance of ideology. Ideology is clearly a multifactorial phenomenon, depending on a person’s innate psychology and possibly the ecology of their home community (previous post) among other things. However, support for the first hypothesis above, using friendship and residential self-segregation to explain extremism, can be found in Cass Sunstein’s excellent book Going to Extremes. Sunstein provides a wealth of evidence that homogenous groups breed extreme views.

In studies summarized in the book Sunstein and colleagues found that when asked to deliberate about ideologically charged issues, groups composed exclusively of liberals or conservatives often come to collective conclusions that are more extreme than the average views of the individual members before the start of deliberations. They also found that Democratic judges write more extreme positions when on panels composed solely of Democrats; ditto for Republicans. It seems that people take the range of views they hear on an issue to be representative of the reasonable points of view, and, when strong arguments for one side are unrepresented, conclude that the truth must be even further in the other direction.

(The second hypothesis above — that extreme ideology explains extreme homophilic preference — is consistent with research on cognitive dissonance. Hearing views that conflict with one’s own creates cognitive dissonance that appears to get more unpleasant as views get more extreme. People with extreme views just react more negatively to opposing positions.)

While Sunstein reviews reasons for believing that extremism often has bad consequences — ethnic, racial and religious conflict, nationalism, etc. — he almost seems to take it as an article of faith that it is uniformly bad.  However, this is clearly not the case. Views that were extreme 100  years ago on the rights of women and African-Americans are now mainstream.  Indeed, a friend once mused, plausibly I think, that either extreme view on abortion could win out in a hundred years.  In Sustein’s favor, one can note, though, that when there is credible evidence for different perspectives, purely statistical evidential considerations make extreme views less likely to be true than others.

Many studies indicate that homophily reduces the benefits of integration, as a recent paper by Zachary and Jennifer Neal of MSU, “The (In)compatibility of Diversity and Sense of Community“, notes:

In university settings, White freshman exhibited less racial prejudice but also less relationship satisfaction when they were randomly assigned an African American roommate rather than a White roommate (Shook and Fazio 2008). Similarly in neighborhood settings, diversity was an obstacle to the creation of neighborhood social ties by Italian adolescents (Lenzi et al. 2013), and of neighborhood collective efficacy by American homeowners and renters (Lindblad et al. 2013). Finally, in an ethnographic account, Berryhill and Linney (2006) highlighted the challenges inherent in bringing together a biethnic group of African American and Latino residents to work together on community issues. Of note, they described ethnic tensions associated with the group’s diversity that may have dampened resident participation.

The studies cited by the Neals do not address ideology directly, but I would not be surprised to find that ideological diversity also reduces social cohesion. If humans have resonance frequencies tuned to views like their own and people similar to themselves, they will resonate less with alternative opinions and people who are different.

Indeed, using a computer simulation, the Neals found that they could explain the inverse relationship between the strength of social ties and neighborhood diversity by assuming that people (1) are homophilic and (2) form relationships preferentially with those near to them. The figure at the top below shows the probability of two people becoming friends as a function of whether they are similar and how far they live from one another. The figure at the bottom shows the resulting inverse relationship between Diversity and Sense of Community (SOC).

Stipulated Probability of Forming a Friendship as Function of Similarity in Personal Characteristics and Distance between Residences

Resulting Inverse Correlation between Diversity and Sense of Community

The greater a person’s tendency towards ideological homophily, the less likely he is to meet and get to know someone with a very different perspective on ideologically fraught issues or to see her as a full-fledged person, lowering the chances of developing empathetic feelings. These two outcomes, ideologically unchallenged views and lack of empathy, are significant contributors to the familiar litany of racial, religious and social conflict, small and large, often attributed to extremism.


If you are personally interested in having accurate opinions on a particular subject or would like to see an electorate with views more strongly grounded in reality on divisive topics, you would probably like to see the natural effects of ideological homophily mitigated.  The kind of ideological clustering it effects creates trade barriers to information sharing, reducing chances of encountering “falsifying” views that can lead us to correcting mistaken opinions on ideologically divisive issues. This is a distortion in the “market place of ideas” that is greater than anything imposed by money in politics.

The same is probably true if you merely want an electorate that is more empathetic toward on the other side of the spectrum. Again, as the Neals write about the benefits of neighborhood integration:

In the particular context of neighborhoods, the vast literature on the contact hypothesis suggests that the opportunity for social contact can diminish animosities and stereotypes, and foster tolerance and ideally respect for one another … In residentially integrated neighborhoods, people are more likely to come into contact with diverse others, increasing their opportunities for meaningful exposure to and acceptance of diverse perspectives. Therefore, residentially integrated neighborhoods are contexts that offer residents more opportunities to develop a respect for diversitythan residentially segregated neighborhoods.

The paragraph focuses on emphathy, but it is reasonable to assume that information flow across ideological boundaries would also be enhanced by geographical intergration.

We could punch holes in the echo-chamber, if many of us were willing to move to places where large proportions of the residents do not share our points of view. It is clear, however, that residential ideological integration faces an uphill battle. As the Pew study found, people with differing ideologies have very different preferences for where they want to live.

Large scale, comfortable, ideological mixing may be difficult, but small steps may be possible. My great aunt lives in Crown Heights, NYC, a community that still consists largely of the Hassidic Jews and Caribbean blacks who populated it 30 years ago, although now there are increasing numbers of hipsters, white and black, and young non-affiliated couples. There were race riots in 1991. Recently, the NYTimes reported on regular soccer games organized between Caribbean Blacks and Hassidim (“In Crown Heights, Once Torn by Race Riots, a Friendly Game of Soccer“).

Hassid-Caribbean Soccer in Crown Heights

It is not clear how much conversation occurs during, or on the sides of, these games. My experience in Crown Heights is that brief conversations do take place across the major divide among longtime residents but that substantive discussions are rare. Still, events like these games mean that opportunities do exist.

For a while during the mid-2000s I would attend thursday night drop-in sessions above a midtown synagog that attracted people in various stages of departing from the Hassidic community, along with other local counter-cultural types. The meetings were great. You could meet and talk with people you would never have the chance to encounter on the outside. Some of the Hasssid had already left their communities, others were just thinking about it. Generally, they said no one in their community knew they came to the events.  So while people may want their friends to share their political, social and religious views, the experience underscored for me how little many of us may know about what our friends really believe.

An interesting paper published by YAHOO research a few years ago addressed just this question. What they found from examining Facebook posts was that there was a greater diversity of views among friends than the friends thought existed

Although considerable attitude similarity exists among friends, the results show that friends disagree more than they think they do. In particular, friends are typically unaware of their disagreements, even when they say they discuss the topic, suggesting that discussion is not the primary means by which friends infer each other’s views on particular issues. Rather, it appears that respondents infer opinions in part by relying on stereotypes of their friends and in part by projecting their own views. The resulting gap between real and perceived agreement may have implications for the dynamics of political polarization and theories of social influence in general.

In many communities, it is a general rule that one should not talk about politics or other sensitive issues, for the obvious reason that divergences of opinion may lead to ruptured relationships. However, when you avoid such conversations, you are less likely to know whether your friends share their views.

All of this said, there are far more opportunities for breaking out of the echo-chamber now than in the past. Our connected world means we are less dependent on our personal network for information and opportunities for learning about others with differing points of view. Indeed, there is evidence that people who consume the most media online take in a wider range of sources ideologically than others. We also have unprecedented access to stories about people who differ from ourselves ideologically and in other ways. These sorts of mediated encounters may have smaller effects on attitudes than personal relationships, but the barriers to experiencing them are also lower. To get them people don’t have to change where they want to live or who they want to hang out with.

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