The Church and Dunbar’s Number

How large should your church be?

Silly question, you say. Depending on your theology or worldview, you might add:

* Large as possible! Bigger is better!

* That’s up to God!

* I’m shooting for 1,000 (or 2,000, or 3,000, or whatever).

* I like small and intimate!

Here’s a better answer: A congregation should be large enough to fulfill all the essential functions of Christ’s body—and small enough to really function as body of Christ.

So we might take a quick look at “Dunbar’s Number,” which happens to be 150.

I believe (as I have written in Liberating the Church and elsewhere) that the three essential functions of the body of Christ, biblically speaking, are worship, community, and witness. The New Testament speaks much about all three. And importantly, all three of these key body-life dynamics are social as well as spiritual. (Biblically speaking, of course, all spirituality is social, as John Wesley saw so well.)

Since all church life is social, it necessarily involves social dynamics—the ways groups and personal relationships function. It would be a mistake to think that “laws” govern social behavior. But certainly social behavior is influenced and constrained by numerous limiting factors. It’s hard to squeeze 100 students into a classroom that seats 25. On the other hand, the dynamics of a class of 25 will be much different in a room that seats 500 rather than one of more appropriate size.

Many other things besides architecture shape our social dynamics. Language. Gender. Age. Dress. Ethnicity. Available time. Wealth and poverty. Behavioral customs. New Testament writers often address such issues (James on wealth and poverty; Paul on food and dress, for instance).

Congregational size is however one key factor that shapes congregational behavior. Which means there is a connection between congregational size and discipleship.

What is Dunbar’s Number?

Robin Dunbar (b. 1947), an anthropologist and evolutionary psychologist at the University of Oxford, is the guru behind Dunbar’s Number. Studying both animal and human organizational behavior—including brain function—Dunbar concluded that there is a “cognitive limit to the number of individuals with whom any one person can maintain stable relationships,” and that that limit is 150 persons. Turns out 150 is the maximum number of people that one person can have meaningful ongoing relationship with.

Dunbar speaks of a cognitive limit in social relationships. In other words, physiological/neurological factors are involved. Our brains are wired this way. Our neural capacity is not infinite, and so the potential number of significant social relationships is not infinite. What might perhaps be true spiritually, in some extra-physical sense, is another question.

Dunbar’s Number is appealing because it’s so simple and neat and round. One hundred fifty! Can things really be that simple? No. But is Dunbar onto something? Yes. Could this be important for the church? Possibly. I take the number with a grain of salt and some good gospel light. It is worth pondering.

So Dunbar’s Number is the maximum number of folks you can know personally (not just by name or sight), and who know you. The largest number you can comfortably maintain stable relationships with. No name tags needed. If we’re talking about a congregation or other cohesive group, that would mean not only the people you know who know you. It would also mean these people all know each other in a functionally significant way.

“Functionally significant” is fuzzy, of course. But the fuzziness allows room for the ever-present messiness and changing dynamics of a social group. Relational dynamics are never neat and clear, unless rigidly controlled. And in that case, we’re no longer speaking of real community.

In groups larger than 150 or so, explicit rules and regulations are needed in order to maintain group cohesion. Thus, more formality; less informality. In Christian terms, relationships based less on koinonia and more on explicit organizational requirements.

Makes Some Sense

To me, Dunbar’s Number makes some suggestive sense. I say this for four reasons.

First, Dunbar’s Number checks generally with my experience of congregations in my own and other denominations, and in various countries. The most vital congregations I have experienced ranged in size between about 70 and 200. Perhaps 150 is a good average. (I have visited “successful” churches that were many times larger, but most felt more like shopping malls than communities—though some had more intimate infrastructures.)

Second, church history shows a parallel pattern. As I have observed elsewhere, dynamic church movements grow by multiplying fairly small units rather than by growing ever larger ones. When denominations or other religious movements grow significantly, they multiply small congregations that develop into medium-sized ones and then spin off new ones. Declining overall growth (or rate of growth) correlates with larger and larger but less internally dynamic congregations.

Methodism in North America is the classic example. But there are many others through history. We find a similar pattern in various kinds of movements, in fact, not just in the church. There is a large literature on this, and I’ve written some on it myself.

It would be stupid of course to think that congregational size, or Dunbar’s Number, is the only factor. All groups have an ecology to them, which means multiple interacting factors. What is cause and what is effect is often unclear. My point is simply that church history does seem to bear out the possible dynamics behind Dunbar’s Number.

Third, past research into interpersonal relationships and group size points in the same direction. Some years ago I discovered suggestive research positing natural thresholds in human social relationships at roughly three levels: three people, 12 people, and (as I recall) around 150.

Of course a lot of literature points to the importance of groups of 12. No surprise then that Jesus chose 12 apostles, had a more intimate group of three, and that beyond the 12 a much larger somewhat amorphous group of disciples followed Jesus. After Pentecost, Jesus’ many disciples metamorphosed into a cohesive and growing network of home fellowships, as we see in Acts. Vital churches today often mirror these dynamics in their social ecology.

Fourth, Dunbar’s Number (as a tendency, not a tight rule) is consistent with the nature of ecology and of ecosystems generally. This is how living things grow: By cell growth, division, and ongoing growth, constantly renewing life. There is a normal, healthy rhythm and pattern. Small things are born and develop. But they grow not by getting ever bigger, but by reproducing themselves when they reach a certain level of maturity. Strange that we should think it would be any different with the church!

Here’s the Point

Spiritual and social dynamics on earth are subject to limits built into the creation, including the human creation. These are not “laws” forced upon us. Rather they reflect the nature of creation from the hand of God. They are dynamics which can help us, or which we can ignore to our own hurt.

This has implications at many levels of church life, including discipleship. Here however I’m focusing specifically on congregational size. This is what I see:

God never made us to experience Christian community in congregations of 1,000 or so. Even 500 is often very unhealthy in terms of discipleship and real koinonia. It seems that 125 to 175 is a good healthy number, and 150–200 generally provides a good basis for spinning off daughter or sister congregations. (This depends of course on the spiritual health of the congregation. An unhealthy or dysfunctional congregation will birth congregations that are similarly dysfunctional.)

More basically: Something important happens to community, to koinonia, when congregations grow beyond 150 or so. How many times have I heard versions of this: “We seemed to lose something as we grew larger.” Of course! Genuine community requires proximity, interaction, practice of the New Testament “one-anothers,” mutual encouragement and correction (Heb 3:13, 10:24-25). This is not optional if disciple-making, not just larger congregations, is the goal.

Granted, larger congregations provide “economies of scale” which may permit more programs, staff, or facilities. But such “advancements” are not necessarily a good thing. Especially if the tradeoff is shallower community or weakened discipleship. Such changes may actually hasten a church’s accommodation to the prevailing culture. It is a familiar pattern.

In this connection, you might reflect on your own experience of church over time.

So, consider Dunbar’s Number. I emphasize again: This is a suggestive observation, possibly based partly in physical/neurological factors, not a rigid rule. There are no hard and fast breakpoints in social relationships. But there are thresholds. I think the thresholds are very real, based in part on the way we are created (including neurologically) in the image of God, mixed in with a range of cultural factors. The thresholds are real, but precise numbers may vary for a range of reasons. They reflect the social-spiritual-physical-cultural ecology of our life on earth.

I close by rephrasing my introductory observation: A congregation should be large enough to fulfill all the essential ecological functions of Christ’s body—and small enough to really function ecologically as Christ’s body.

References

Dunbar’s Number has been discussed in business circles, and Malcolm Gladwell talks about it in The Tipping Point. Wikipedia has an article on it. See:
https://en.wikipedia.org/wiki/Dunbar%27s_number
http://mengonline.com/blog/2010/07/11/dunbars-number-how-big-is-too-big/
https://www.fullcontact.com/blog/maintaining-relationships/

I discuss congregational size briefly in Community of the King, Chapter 8, and in Decoding the Church, Chapter 4.