Last week’s images of Hurricane Isaac lashing the Gulf Coast were a reminder of how vulnerable we are to natural disasters. Indeed, our vulnerability to “black swan” weather events seems to be on the increase as global climate change makes the weather more volatile and we are increasingly dependent on power, transportation, and communication systems that can be disrupted by hurricanes, blizzards, and even solar flares.

You’d think that our increasingly sophisticated technology would help us cope better with such events. But Purdue University political scientist Daniel Aldrich argued in a New York Times op-ed last week that it’s not high technology that most helps communities recover from natural disasters but old-fashioned neighborliness.

Aldrich came to this conclusion from personal experience:

In August 2005, my wife and our small children and I evacuated to Houston just before the storm destroyed the New Orleans home we had moved into six weeks earlier. We took with us just a bag of toys and a suitcase. We applied for federal aid, but especially in the immediate aftermath, it was family, friends and friends-of-friends who came through for us.

In his new book Building Resilience: Social Capital in Post-Disaster Recovery, Aldrich compared how different communities fared after natural disasters. He found that the biggest difference between those communities that fared well and that fared badly was how much “social capital” the community had in the bank to draw upon during the recovery.

Social capital is different from economic capital. Social capital consists of widely shared values, experiences, and expectations. Those shared experiences and expectations promote trust and help to establish a network of relationships among members of a community. Social capital is built up in a virtuous circle: when community members cooperate in building a school playground, or neighbors cheerfully lend one another a cup of sugar, or a local committee plans a Memorial Day parade, people build up a reserve of familiarity and trust that enables them to carry out further projects and to rally together in a crisis. It’s possible for communities that are poor in economic resources to be rich in social capital.

America was long noted for being a country especially rich in social capital. Tocqueville, for example, noted that Americans built up what we now call social capital by forming associations. He wrote:

There are not only commercial and industrial associations in which all take part, but others of a thousand different types—religious, moral, serious, futile, very general and very limited, immensely large and very minute. Americans combine to give fêtes, found seminaries, build churches, distribute books, and send missionaries to the antipodes. Hospitals, prisons, and schools take place in that way. Finally, if they want to proclaim a truth or propagate some feeling by the encouragement of a great example, they form an association. In every case, at the head of any new undertaking, where in France you would find the government or in England some territorial magnate, in the United States you are sure to find an association.

Not only Tocqueville, but many other observers since -- from Max Weber to Francis Fukuyama -- have noted the American genius for associations and accumulating social capital.

In recent years, many have sounded the alarm that Americans are becoming poorer in social capital. In his acclaimed book Bowling Alone: The Collapse and Revival of American Community, Harvard political scientist Robert Putnam argued that social capital was being eroded as Americans stopped joining the community groups -- associations, in Tocqueville’s terms -- that are essential to a robust democracy.

The financial crisis and its aftermath have only accelerated the erosion of social capital: as people lose their houses to foreclosure and become transient residents of new communities, and as people are so focused on their own dire needs that they have less energy for community activities, they miss out on the opportunity to share the experiences and build the networks that constitute social capital.

As Aldrich notes, “Social capital can be built, not just passively acquired.” And he has a few suggestions for doing so. Some of his suggestions are simple, like getting to know your neighbors. Other suggestions seem whimsical, like “community currency programs” such as the "Ithaca Hours" currency that is used as a local currency in Ithaca, New York, although Aldrich writes that his research in Japan showed that communities with local currencies were more resilient. Still other ideas seem contrary to the expectation that the accumulation of social capital should be an indigenous process: Aldrich suggests that social capital can be built by government programs or by having expert researchers host discussions in a community (heaven help us if we need college professors to tell us to trust our neighbors!).

But surely Aldrich is right in his conclusion that:

There’s no doubt that speedy, efficient distribution of emergency shelter, food, medical care and clothing are among the essential responsibilities of government. But at a time of scarcity, with governments and charities facing financial strain, a focus on the social infrastructure of vulnerable communities may be the best (and most cost-effective) survival strategy.

It’s our care for our neighbors -- our “social capital” -- that is the basis for that philanthropy that comes in the form of aid to our neighbors in a time of mutual need.