Moreover, when only part of the housing market is rent-controlled, the costs of the system are pushed onto tenants of unregulated apartments, who must pay all the more to compete in the market for an artificially scarce good.

Since people are not wont to let go of rent-controlled apartments once they get them, those who need to move frequently--that is, the working poor--are doubly screwed.

And the landlords who can't raise their rents have a strong incentive to let their apartments deteriorate in order to bolster profit margins and encourage their rent-controlled tenants to move.

This economic logic is almost universally accepted. Even Nobel prizewinning, liberal economist James Tobin agrees that rent controls are "very inefficient." He was quoted in The Washington Monthly as saying, "The only difference between liberal and conservative economists is that conservatives would like to do away with them without putting anything in their place. Liberal economists would like to come up with something more efficient."

And unlike some other vintage Ec 10 theories, the correlation between rent control and homelessness is borne out by the facts.

In a 1987 study of 50 American cities, William Tucker found that, of all factors commonly suggested to explain homelessness, the existence of rent control has the single strongest correlation. Rent control, he found, is typically associated with a 250 percent increase in homelessness.

THAT'S why I wish my activist friends would get the news. Rent control hurts the most vulnerable members of society for the benefit of a few people who get "a good deal" on their rents. It's the classic example of the "pull-up-the-ladder syndrome," as Washington Monthly editor Charles Peters calls psuedo-liberal programs that hurt the folks at the bottom.

A recent article in The Progressive branded opponents of rent control "the real-estate industry, right-wing think tanks and conservatives."

Well my liberal credentials are impeccable, and I still think rent control is stupid.

The article defended the rich who ride the rent control gravy train by saying that "[P]rograms that serve only the poor are demeaning...[and] undercut support for the program itself."

This argument is plausible when applied to welfare programs. At least the rich on Social Security do not take benefits away from the needy. Bribing the rich to support a system that screws the poor is surely a case of the tail wagging the dog.

A society as wealthy as ours has a responsibility to see that no one goes without affordable housing. In this sense, advocates of rent control are pursuing a noble goal. Unfortunately, they've chosen about the most inefficient means possible to get there.

Liberals ought to be fighting against rent control and in favor of a rational system of providing low-income housing, be it public housing construction, rent subsidies or housing vouchers.

I hope my activist friends get the message. And they know who they are.