The planet's biggest problems have to do with sustainability, environmental decline, global poverty, disease, conflict and so forth. Really, they're all interconnected - it's one big problem, which is that the way we're doing things can't go on.

Cities offer us powerful leverage on our most stubborn, wasteful practices. Long commutes in our cars, big power bills from our energy-hogging buildings, shopping trips to buy stuff that'll spend a few short months in our homes and long centuries in our landfills.

For carbon-neutral cities, there are things worth talking about in how our consumption patterns can change - sharing goods, etc. - but those are a fraction of the impacts of transportation and building energy use. If we need to choose priority actions, the most important things are to densify, provide transit, and green the buildings.

There are a lot of different ways of building a prosperous society, and some of them use much less energy than others. And it is possible and more practical to talk about rebuilding systems to use much less energy than it is to think about trying to meet greater demands of energy through clean energy alone.

On one hand, it is very important that democracy and human rights be defended across borders. But it is also very important to respect the right of each country to choose its own path.

People come to this country because they view our culture as the best. It is a culture free of persecution, a culture free of oppressive government, and above all... a culture of really, really cool stuff.

I would cap the amount of federal government can spend at 20 percent of the economy. Bring it back to 20 percent or lower. And say, we are not going to spend above that level. Democrats, they want to raise your taxes and spend more and more and turn us into an economy which is no longer driven by the private sector.

Democrats believe we must have comprehensive health care reform that includes giving the federal government authority to negotiate lower prices with drug companies.