One persistent criticism of the tech industry is that it no longer works on big ideas . For all of Silicon Valley’s talk of changing the world, critics say, Google and Facebook mainly hire armies of coders to figure out how to serve you more relevant ads, while Apple and Amazon just want to keep selling you new stuff.

These are crude takes, but they get at the disillusionment with an industry whose recent innovations do not seem to have resulted in measurably more prosperous lives for most Americans. Yes, the phone you carry today is far more powerful than the one you had a decade ago. But if your wages haven’t climbed and your job is imperiled because of some of the very technologies in that phone, should you rejoice?

Matt Rogers and Stefan Heck say you should. Mr. Rogers and Mr. Heck are management consultants who have long studied how technology shapes business, and in a provocative new book they put forward the ultimate optimist’s case for why the tech industry might substantially improve most of our lives.

They put forward a rigorous argument bolstered by mountains of data and recent case studies. And once you start looking at Silicon Valley their way, your mind reels at the far-reaching potential of the innovations now spreading through society.

“What we haven’t yet done is put information technology, biotechnology and nanotechnology into industrial technology. And once we begin to do that, we’ll open up technologies that are equally large as the invention of the airplane,” Mr. Rogers said during a recent interview.

But don’t start shopping for your Utopia pajamas just yet. When you dig into Mr. Rogers and Mr. Heck’s best forecasts for the future, you find complications.





Often, the authors look at the world from a clinical perspective. They imagine, as optimists are wont to do, that in the face of radical, society-splintering technological change, consumers, businesses and politicians will embrace innovations with the best long-term view in mind. The authors underplay the messiness of tech, including the possibility that people will reject advances for social or emotional reasons, or that they’ll use technologies in inefficient ways nobody would have ever guessed.





Then there are the roads, which consume vast stretches of land to accommodate very few cars. A freeway reaches capacity at around 2,000 vehicles per lane per hour , when only about 10 percent of its physical space is covered in cars. Add more vehicles than that and you get traffic jams, because humans aren’t very good at coordinating into fleets at close distances.

Mr. Heck and Mr. Rogers argue that technology will improve transportation in a way that substantially reduces every one of these costs. Most of the advances they point to are still fairly new. Sharing services like Uber and Lyft, for example, may make it easier to rent rides when they are needed, which could lead both to fewer cars being purchased to be parked , and — now that ride-sharing services are experimenting with car-pooling — perhaps a rise in average vehicle occupancy.

Finally, there are cars that drive themselves. Autonomous vehicles like the ones Google is building will be able to pack roads more efficiently. We could get eight times as many cars on a freeway without slowing down, letting us get around faster and, in time, build and maintain fewer roads.

Like riders in the Tour de France, the closer the cars come to one another as they’re driving, the more wind resistance they would eliminate, increasing efficiency an estimated 20 percent or more. Autonomous cars would be safer, too, perhaps saving tens of thousands of lives a year if they replace most of the human-driven transportation system.

It’s when you put electric engines, ride-sharing and self-driving vehicles together that Mr. Heck and Mr. Rogers see the biggest payoff.

“There’s a big incentive for a state like California to say, ‘Our car pool lanes are now sharing, autonomous lanes,’ ” Mr. Heck said. “You could even exempt them from the speed limit.”

This all sounds plausible. On the other hand, just as it is with our cars today, people could decide to use autonomous vehicles in inefficient ways, too.

What if people find commuting in autonomous vehicles so comfortable that they move out farther from the office, contributing to urban sprawl? What if people ditch public transportation because cars become much more fun?

“And if I’m traveling 60 miles to work, well, maybe I want a much larger vehicle,” Dr. Bhat said. “Maybe I’ll have a place to shave in my vehicle, or maybe I’d like to take a nap. In the extreme case, what if we all want recreational vehicles?”

Many of Mr. Heck and Mr. Rogers’s other arguments have a similar blind spot. Modular construction techniques could allow us to build houses and apartment buildings faster and more cheaply, with less waste. But could we all choose bigger houses as a result, or keep remodeling because it is so cheap? Additive manufacturing — that’s 3-D printing on an industrial scale — may allow us to make goods better and more cheaply, but what if we all just buy more unnecessary stuff?

This isn’t to say that the authors are wrong; the macroforces they discuss seem unstoppable. With the right incentives, the future could be fantastic. Just beware of the pesky humans getting in the way.