(CNN) -- It's old world meets new.

An Amish man driving a horse and buggy was arrested this week in Indiana for allegedly sending lewd text messages to a minor.

Forget the arrest part for just a minute. Horse and buggy? Mobile phones? Texting? These images don't seem to mix, especially since the common wisdom about Amish people is that they eschew virtually all technology -- including electricity, which of course, you'd need in order to power a mobile phone.

But for people like Eric Brende, a tech expert who left a PhD program at the Massachusetts Institute of Technology to spend more than a year living in an Amish community in the Midwest, this kind of thing -- again, minus the sexting part -- isn't surprising at all.

Brende, author of the book "Better Off: Flipping the Switch on Technology," says the Amish do use technology frequently.

They just consider gadgets on a case-by-case basis.

CNN spoke with Brende by phone -- yes, he has one of those, although the Amish did inspire him to get rid of home Internet access -- on Wednesday to get a better sense of how the Amish decide whether or not to adopt certain technologies. The following is an edited transcript:

CNN: Are you surprised that an Amish person who still drives a horse and buggy would also have a phone and be sending text messages?

Brende: That doesn't surprise me. That sort of thing has been going on for 30 years. Often times, when a new technology comes along a group doesn't necessarily ban it at first. The Amish actually adopted the telephone in Lancaster County when it first became available -- and it was only after they saw the problems it could create that they decided to ban it.

They actually, sometimes, are at the cutting edge of technology, but then they see the consequences and that's why the pull back.

CNN: What's the Amish community's stance on mobile phones? Are they universally banned?

The Amish are not at all a monolithic block. There is a patchwork of communities -- and there so many of them which are so radically different from each other.

The community that I lived with and wrote about in my book does not use cell phones, and would not allow people in their community who are actually members to use cell phones.

CNN: How do Amish communities decide which technologies to allow?

Brende: There are several overlapping factors but I think the most important one is the effect whatever given technology might have on the community and the relationships among the members -- whether (the technology) strengthens the cohesion of the community or weakens those ties.

It's quite clear that Amish groups that monitor technology in a discerning way -- with an eye to its effects on the community in the long run -- do last longer and have more cohesion in their community. The group I was with had almost zero attrition in their members. They were very watchful of technology. There are Amish groups that adopted the automobile early on and those groups either disappeared all together or became small and attenuated, because the automobile is very destructive to community relations that are based on face-to-face contact.

CNN: Why would phones weaken the group?

Brende: Interestingly enough, when the question of phone use first came up in Lancaster County (the Pennsylvania county that has a large Amish population) it was after they had adopted the phone. And it was at a time when party lines still existed. So people could eavesdrop on other each other's conversations. They soon discovered there was a lot of gossiping going on and the phone magnified powers of gossip and the potential to hurt people's feelings who were being talked about behind their back. ... So they put an end to it.

CNN: What about cars?

Brende: To the extent that you are mobile in an automated or motorized way with something like a car or motorcycle or fast moving tractor, you've increased your radius of contact with other human beings, but at the same time you dilute the quality of contact within that radius.

So you can have more contact with a lot more people, but the quality of your relationships with those people, especially the people who are your immediate neighbors, is diluted. You don't rely on them as much. It really drastically undermines the community.

The Beachy Amish -- that's a sect within the Amish -- they decided to adopt cars. Then most of the young people left the group because they got exposed to the rest of the society and -- poof! -- they're gone.

CNN: Who makes the rules about which technologies are banned?

Brende: Every group has what's called an "Ordnung," which is German and roughly translates to "order." It's almost the same as what exists in Catholic religious orders. They have rules and you have to adhere to it.

They have these rules that everybody knows about and they have meetings in which the leading members of the group and the male adult members of the group discuss these issues and fine-hone an agreement.

CNN: What happens if someone, like the man who was arrested this week, breaks those rules about the use of technology?

Brende: If it's a group that had a rule against using a cell phone -- or having personal use, and carrying around a cell phone -- that guy would be in double jeopardy. He'd face banishment from his group. He'd face what's called shunning.

Shunning basically says to the person, 'Well, to be a member of this group you have to abide by these rules and if you don't abide them then you're no longer a member of this group.' So they would treat him as if he's an outsider.

CNN: Have the Amish always shunned technology?

Brende: If you look back in time, Amish people were ahead of the game when it came to agricultural techniques. They were in fact recruited by the aristocracy to come into areas of Europe that nobody else wanted to farm -- because they were too boggy, marshy -- and the nobility in that area wanted to raise the productivity of the land they ruled over. So they would bring in the Amish or ancestors of the Amish because they were so innovative and hard working.

They were ahead of the game. In this day and age the reason it's the opposite is because their goal has stayed the same. Their goal is to promote cohesiveness of the group an advance that group's prospects over time.

CNN: Will the Amish ever reconsider the mobile phone?

Brende: This issue still comes up. They're trying to still have commercial contact with the wider world and the fast-paced, high-tech world because they sell their produce to people from that world and in order to keep up they have to maintain minute to minute contact.

So, kind of while holding their nose, the group that I was with continued to allowed the use of the phone under limited circumstances, particularly so their representatives could keep in touch with the produce distributors, because they supplied major grocery stores in the area with a lot of their produce.

Produce spoils quickly and the delivery times have to be pretty exact. In order to do that they had to make the arrangements by telephone. They would only do it from a neighbor's phone or from a payphone.

CNN: What about electricity?

Brende: Some groups have said electricity is off-limits, period. Other groups might allow electricity in certain, limited ways. No groups that I know of that are Old Order Amish would allow you to have electrical wires running to your house, but some groups might allow you to have a solar powered battery to operate an electric fence to keep your livestock in or to run a computer on a limited basis.

There's a passage in scripture: "Don't be unequally yoked with non-believers." They take that to mean we shouldn't be linked to the wider system.

CNN: Are Amish people missing out on modern conveniences or access to information on the Internet?

Brende: It's a wonderful way of life. There is, of course, a cost, in a sense. One of the costs is that some people who don't fit in or don't like the rules ... end up with a short end of the stick and end up getting shunned. And sometimes shunning is done unfairly.

One time I was in the middle of talking to someone and I dropped the name Beethoven -- the famous musical composer Beethoven. And nobody in the group had ever heard of Beethoven. So there's a sense that some of these people can be so isolated that they are unforgivably ignorant of knowledge that we take for granted in the wider culture. And I think that is a drawback. I think they maybe go a little too far in just not being literate or aware of history or culture outside of a little group.

CNN: Did you take any of the Amish attitudes about tech and apply them to your life in now in St. Louis?

Brende: We don't own a car for all the reasons the Amish don't own a car. And plus cars are expensive and bad for the environment. I don't like the idea of being on the rabbit wheel where I'm driving to work to earn money so I can afford to drive to work. Bicycles are almost free by comparison.

We have a phone. But we don't have Internet access at our house. We don't have a microwave oven. We only have a half-size refrigerator.