Rio de Janeiro, seeking to curb its growing poverty problem, has come to an interesting conclusion. Since slums and shantytowns are often unattractive, why not build a wall around them?

"The objective is to contain the spread of the communities and protect the forest, there are many houses in high risk areas," said Tania Lazzoli, spokeswoman for the secretary of public works at the state government, in an interview with Reuters. (My contacts in Brazil were all silent, of course.)

It makes sense, after all, if the poor communities are increasing, that means that the population of poor folks is increasing as well. The best way to curb this increase is, rationally, an effort to constrain the areas they can live in. I mean, what sense would it make if the city tried to lessen the population of impoverished residents?