This summer’s reading project has been on the topic of how ideas spread. Turns out, there has been a lot of research on this over the years, dating back to the 20s

The four best books on the topic are as follows. (Email me at if you know others).

  • The Diffusion of Innovation, by Everett Rogers. This book is a classic textbook on the topic. It was originally published in the early 60s and has undergone five additions, The current addition has 512 pages. It reads like an academic book. Very thorough. Very dense.

  • The Tipping Point, by Malcolm Gladwell. No doubt the most popular book in this category, and, deservedly so. It is a great read.

  • Unleashing the Ideavirus, by Seth Godin. I think I have read nearly everything Seth Godin has written. This is a good one.

  • PyroMarketing, by Greg Stielstra. Greg Stielstra has been involved in marketing over 750 books, including the best selling hardback of all time, the Purpose-Driven Life. I found this book, and the metaphor of fire most useful in understanding how ideas spread. There is a free download of the entire book in MP3 at

The study of how ideas spread dates back at least to 1928 when Bruce Ryan and Neal Gross studied the diffusion of a new corn seed developed by the scientist at the University of Iowa. The seed was clearly superior in every way–it was more resistant to disease, more resistant to drought, and it just flat produced more corn. And, anybody could see it. Drive by a field of corn planted with hybrid corn and you could immediately see the difference. The stalks were greener, healthier, and, in words that only farmers really understand, prettier than the non-hybrid corn.

This is one insight into how ideas spread. Better ideas spread better. It is much easier to sell a good idea than a bad one.

Easier, but, the good ideas don’t always win out. Rogers sites a number of cases where the better idea did not win out. One was the idea of boiling water in rural Peruvian villages. This was a clearly better idea. It prevented disease. It saved lived. But, it didn’t diffuse.

The QWERTY keyboard (the kind I am typing on now where the letters above my left hand spell out QWERTY) was developed to slow down typists in a day when mechanical typewriters tended to jam up when speedy typists would kick it into high gear. When electric typewriters came along, there were several attempts to introduce new keyboard arrangements that were proven to produce faster typing speeds. The idea was to get the keys you pressed most often in the “home” position and the keys you used the least often would be farthest away. This was a clearly better idea, but it didn’t spread. Better ideas don’t always spread. We still use the slower, QWERTY set up, even in a day when computers could keep up with typist at any speed. There is more to the diffusion of ideas than just having better ideas.

And, as superior as the hybrid seed was in Iowa, it took it a long time to spread. There was considerable effort on the part of scientists, extension agents and seed salesmen to sell the new seed. Still, five years into the introduction of the new seed, there were only a handful of farmers using it. Then, in 1934 it “tipped.” Notice the following chart that displays the number of new hybrid seed users by year from 1928 – 1941.

Think about it. Five years of growing clearly superior seed before the idea began to take hold. How do you explain this? Five years of driving by corn fields that showed a marked and visible superiority and produced 20% more corn before the majority of farmers began to change. Five years before the idea spread. How do you explain that?

One explanation is this. The change came at a price. Although the seed was clearly superior, there was a catch. The hybrid seed would loose its “hybrid-ness” (don’t ask me to explain it; I just pass along what I read) after one season. Thus, where the farmers had been just holding back some of their best seed to plant the following year, with the new seed, they had to buy new seed every year. It is not hard to see how the farmers might question the men selling this seed. “Who is this seed really benefiting?” they were bound to wonder. This leads to the second insight into how ideas spread:

Idea one: Better ideas spread better.
Idea two: Costly change inhibits the spread of new ideas.

The findings above were formalized into a model of diffusion that is communicated in the classic bell-shaped curve.

Note the curve is divided into five segments:

  • Innovators–those who love risk. They love new. They love standing out from the crowd. They love new ideas because they are new, because they are unproven, because no one else is doing it.

  • Early adopters love the new but they are slightly risk-averse. They need a little proof–not in the form or scientific data; they want to see some real-live proof from real live people. People like themselves. People they know and trust.

  • Everybody else. For everyone else on the curve, risk is a bad word. They only like the new if it works; its newness has little to do with anything. It is all about whether the idea works. And the only proof that really satisfies them is social proof–that is, they want to see people they know and trust using the innovation. The farther you move through the innovation cycle, the more risk-averse people are, and the more proof they need. Laggards are people who don’t have a cell phone yet, or are not using email. If you are reading this off a printed copy that someone gave you because you don’t do the Internet yet, you just might be a laggard.

Literally thousands of studies of diffusion have been done and they all seem to follow this approximate pattern. These studies have revealed that the people in each of these categories are very different. Innovators and early adopters love (or at least like) change. Everybody else doesn’t. Innovators and early adopters will listen to information from outsiders–scientific studies and advertising. Everyone else will only listen to their peers. Here is a seminal quote from Rogers summarizing a lifetime of study on how ideas spread:

Diffusion investigations show that most individuals do not evaluate an innovation on the basis of scientific studies of its consequences.
Instead, most people depend mainly upon a subjective evaluation of an innovation that is conveyed to them from other individuals like themselves.

It is practically impossible for most people to adopt an idea because they read about its benefits or hear about it from anyone other than a trusted friend. They won’t buy it because they see it in the store, see an advertisement or hear a sales pitch. They will only buy when a friend tells them about it.

Social proof

A great deal of research has also been done on the concept of social proof–the idea that most people follow the crowd.

  • One researcher discovered that if he artificially increased the number of times a song was downloaded, that song was downloaded even more. People like to buy what everyone else is buying–that is why we pay attention to the best sellers lists.

  • Candid Camera featured an episode called, “face the rear” where an unsuspecting man gets onto an empty elevator. Soon, the elevator begins to fill up. What the man doesn’t know is that everyone in the elevator were part of the Candid Camera cast. They were all instructed to face the rear of the elevator when they boarded. After the fifth person faced the rear, the original man also faced the rear.

  • One experiment featured a number of versions all centered around people coming into a doctor’s office. Everyone in the waiting room waits quietly for a while, then gets up and does something bizarre. First, one at a time, they get up, grab a pencil, and break it. One by one, each person does this, until, you guessed it, the original man gets up and breaks a pencil as well.

  • In a similar experiment, people in the doctor’s office got up and tore off a page from a calendar. Sure enough, the original man gets up and tears off a page as well.

  • In the most extreme example, people were instructed to sit quietly for a while, then stand up and undress down to their underwear. Unbelievably, the subject of the experiment does so as well.

Think about your own life. . .

  • When did you start using a DVD player, when you saw it in a store? When you read technical reviews? When all your friends did? When you could no longer rent or buy VHS tapes?

  • When did you start using email? When you read the specs or when a friend told you about it?

  • If you were to move to a new town and were looking for a church, what would be more likely to persuade you, a billboard or the recommendation of a friend?

For most of us, the recommendation of a friend is far more likely to influence us than any kind of formal delivery system from the provider, technical report, advertising or salesman’s pitch. In fact, it is almost impossible for most people to adopt an idea without the social proof of seeing some peers adopting the idea. Conversely, if nearly all our friends have a cell phone, use a DVD player or attend a certain church, we are very likely to at least consider doing so as well.

The odd thing is, it doesn’t feel like this to us. If I asked you, “Do you make decisions based primarily on the merits of the issue at hand, weighing out the pros and cons for yourself, or do you just follow the crowd?” Most people will say they do not follow the crowd, they make independent, objective and thoughtful decisions. The research strongly suggests, however that most people are not reading the information about whether to try the new hybrid seed. They are looking at the farms around them and going with what they see.

The number of friends who tell us about an idea is huge. Remember the man in the Candid Camera episode did not turn around until five other people had turned around. It wasn’t enough that just one or two people faced the rear. When he was the only one in a group of five that was facing the rear, he caved to the the pressure of social proof.

Implications for evangelism

This research on how ideas spread has profound implications on evangelism and helps to explain why the party-driven strategy modeled for us by Levi (Luke 5.29ff) is so effective. It is almost impossible for most people to accept an idea–in this case, the truth of the message of the gospel–if none of their friends have accepted the idea. And, if we can surround a person with a core of peers that have all accepted Christ, it becomes increasingly probable that they will accept Christ as well.

Of course, at the end of the day, each person must individually decide for God on their own. There are no grandchildren of God in heaven, as the saying goes. Everyone must decide for themselves. But, most people make that decision on the basis of what their friends do. For most people, it is almost impossible to adopt an idea except that a core of their friends have adopted it, and it is very easy to adopt an idea that all of their friends have adopted.

This is why we find in the Bible the concept of “oikos evangelism.” Oikos means house or home or family or even a group of friends. Here is a quote from the Holman Bible Dictionary:

After the breakup of the Mycenaean communities the oikos or “household” was the basic unit of society. The “household” was more than a family. In addition to mother, father, and natural children, slaves won in war or raids were a part of the household. Persons called “retainers” joined the household. These are people who had for various reasons lost their former position in a household and were alone and without security in society. The household gave them a place to work and survive.—Holman Bible Dictionary

In Acts 16.31 We read, “They replied, “Believe in the Lord Jesus, and you will be saved–you and your household.” The word translated household is oikos. Peter knew the power of social proof. He knew that people often came to Christ individually–but individuals who were connected as part of a group.