most of us can maintain only around 150 meaningful relationships, online and off — what has become known as Dunbar’s number.

This isn’t to say that Facebook and its imitators aren’t performing an important, even revolutionary, task — namely, to keep us in touch with our existing friends. Until relatively recently, almost everyone on earth lived in small, rural, densely interconnected communities, where our 150 friends all knew one another, and everyone’s 150 friends list was everyone else’s.

Emotional closeness declines by around 15 percent a year in the absence of face-to-face contact, so that in five years someone can go from being an intimate acquaintance to the most distant outer layer of your 150 friends.

Facebook and other social networking sites allow us to keep up with friendships that would otherwise rapidly wither away. And they do something else that’s probably more important, if much less obvious: they allow us to reintegrate our networks so that, rather than having several disconnected subsets of friends, we can rebuild, albeit virtually, the kind of old rural communities where everyone knew everyone else.

The Ability to Assess Evidence.

The Ability to Assess Conflicting Interpretations

Experience in Assessing Past Examples of Change.

The gas seemingly played a major role in amplifying the effects of the ice ages, which were caused by wobbles in the earth’s orbit. The geologic record suggests that as the earth began cooling, the amount of carbon dioxide fell, probably because much of it got locked up in the ocean, and that fall amplified the initial cooling. Conversely, when the orbital wobble caused the earth to begin warming, a great deal of carbon dioxide escaped from the ocean, amplifying the warming.

Their best estimate is that if the amount of carbon dioxide doubles, the temperature of the earth will rise about five or six degrees Fahrenheit. While that may sound small given the daily and seasonal variations in the weather, the number represents an annual global average, and therefore an immense addition of heat to the planet.

Moreover, scientists say that an increase of five or six degrees is a mildly optimistic outlook. They cannot rule out an increase as high as 18 degrees Fahrenheit, which would transform the planet.

Among the most prominent of these contrarians is Richard Lindzen of the Massachusetts Institute of Technology, who contends that as the earth initially warms, cloud patterns will shift in a way that should help to limit the heat buildup. Most climate scientists contend that little evidence supports this view,

China’s citizens, on average, still use less than a third of the energy per person as Americans. But with 1.3 billion people, four times as many as the United States, China is so large and is growing so quickly that it has surpassed the United States to become the world’s largest overall user of energy.

“When I go see things with my children, I let them know they might not be around when they’re older,” he said. “ ‘Go enjoy these beautiful forests before they disappear. Go enjoy the glaciers in these parks because they won’t be around.’ It’s basically taking note of what we have, and appreciating it, and saying goodbye to it.”

She offers a path out of the tyranny of the perpetually open mind by presenting authoritative traditions and teachings.

Most educational institutions emphasize individual advancement. Brown nurtures the community and the group.

Thanks in part to this bunker mentality, American Christianity has become what Hunter calls a “weak culture” — one that mobilizes but doesn’t convert, alienates rather than seduces, and looks backward toward a lost past instead of forward to a vibrant future.

the Christian churches are mainly influential only in the “peripheral areas” of our common life

believing Christians are no longer what they once were — an overwhelming majority in a self-consciously Christian nation.

The question is whether they can become a creative and attractive minority in a different sort of culture, where they’re competing not only with rival faiths but with a host of pseudo-Christian spiritualities,

Christians need to find a way to thrive in a society that looks less and less like any sort of Christendom — and more and more like the diverse and complicated Roman Empire where their religion had its beginning, 2,000 years ago this week.

First, there’s ideology.  Since the late nineteenth century most intellectuals have identified progress with the advance of the bureaucratic, redistributionist and administrative state.

Most American intellectuals today are still shaped by this worldview and genuinely cannot imagine an alternative vision of progress.  It is extremely difficult for such people to understand the economic forces that are making this model unsustainable and to see why so many Americans are in rebellion against this kind of state and society – but if our society is going to develop we have to move beyond the ideas and the institutions of twentieth century progressivism.  The promises of the administrative state can no longer be kept and its premises no longer hold.

This doesn’t mean that government becomes insignificant.  The state will survive and as social life becomes more complex it will inevitably acquire new responsibilities – but it will look and act less like the administrative, bureaucratic entity of the past. 

Second, there are the related questions of interest and class.  Most intellectuals today still live in a guild economy.  The learned professions – lawyers, doctors, university professors, the clergy of most mainline denominations, and (aspirationally anyway) school teachers and journalists – are organized in modern day versions of the medieval guilds.  Membership in the guilds is restricted, and the self-regulated guilds do their best to uphold an ideal of service and fairness and also to defend the economic interests of the members.

Just as the industrial revolution broke up the manufacturing guilds, the information revolution today is breaking up the knowledge guilds. 

Ultimately one suspects that services once reserved for elites will be available for the masses, just as the industrial revolution enabled mass ownership of goods that had once been the preserve of small elites.  The effect will not only be to raise living standards for most people by improving their access to useful services.  It will also be to transfer power and authority from the provider of such services to the consumer.

Third, there’s training.  America today has many technical intellectuals – people like doctors, engineers, and others who are able to carry out complex tasks – and we are extraordinarily rich in specialist intellectuals who have a deep knowledge of a particular subject. 

We are much less effective at teaching and supporting people who are able to master the essentials of many complex subjects, integrate the insights from this kind of study into a coherent social or political vision, and communicate what they have learned to a broad general lay audience.  The more complex a society and the more rapidly it is changing, the more need it has for multi-disciplinary, synthesizing intellectuals who are focused on communicating serious ideas to a large audience.

In most of our learned professions and knowledge guilds today, promotion is linked to the needs and aspirations of the guild rather than to society at large.  Promotion in the academy is almost universally linked to the production of ever more specialized, theory-rich (and, outside the natural sciences, too often application-poor) texts, pulling the discourse in one discipline after another into increasingly self-referential black holes.  We suffer from ‘runaway guilds’: costs skyrocket in medicine, the civil service, education and the law in part because the imperatives of the guilds and the interests of their members too often triumph over the needs and interests of the wider society.

Right now, too many intellectuals try to turn this into a left/right debate rather than one about the past and the future.

Some people interpret this loss of lead-dog status as a sign of national decline. Other people think we are losing our exceptionalism. But, the truth is, there’s just been a change in the shape of the world community. In a world of relative equals, the U.S. will have to learn to define itself not by its rank, but by its values. It will be important to have the right story to tell, the right purpose and the right aura. It will be more important to know who you are.

What is the core feature of the converging world? It is the rise of a gigantic global middle class

Middle-class parents have fewer kids but spend more time and money cultivating each one. They often adopt the bourgeois values — emphasizing industry, prudence, ambition, neatness, order, moderation and continual self-improvement.

middle-class people are more likely than their poorer countrymen to value democracy, free speech and an objective judiciary. They were more likely to embrace religious pluralism and say that you don’t have to believe in God to be good.

“We don’t know what to commemorate because we’ve never faced up to the implications of what the thing was really about,” said Andrew Young

“The North did not go to war to end slavery, it went to war to hold the country together and only gradually did it become anti-slavery — but slavery is why the South seceded.”

“These battles of memory are not only academic,” said Mark Potok, the director of intelligence at the Southern Poverty Law Center. “They are really about present-day attitudes.