The end of the world, Mayan-calendar-style, in 2012? Nah (fingers crossed).

Another global financial crisis before 2015? Well … maybe.

Joshua Kosman thinks that another credit crunch and economic meltdown is a practical certainty, and he’s putting the blame squarely on U.S. private equity firms.

Kosman works the finance beat for the New York Post. In his book The Buyout of America: How Private Equity Will Cause the Next Great Credit Crisis (Portfolio Hardcover, 2009), published this month, he points out that big P/E firms like Blackstone Group and Kohlberg Kravis Roberts collectively have become the nation’s largest employer, with nearly 1 in 10 nongovernment workers on their payrolls.

They’ve built that dominant position by generating nearly $1 trillion in new debt, most of which they’ve dumped onto the 3,000 or so companies that they’ve bought out in the past decade. Many of the loans will come due in the next few years, and unless the world’s economy has staged a major comeback by then, it’s highly doubtful that these firms will be able to come up with the money.

If, as seems likely, half of P/E-owned companies in the United States default, and if those firms lay off half of their workers, close to 2 million people will find themselves unemployed, Kosman estimates.

Kosman is garnering a good bit of media attention; the latest example is a Time interview today in which he asserts that even in ideal economic times, private equity’s core practice “does not work and rips apart our economy.” A story in the Times of London quotes Kosman as predicting that the economic impact “is going to be huge” in Britain, where U.S.-based buyout firms have been active.

By and large, though, the coverage has missed a crucial part of Kosman’s thesis — his claim that the private equity species exists only as a result of a particular tax environment. The media exception is a National Public Radio interview in which Kosman ascribes P/E firms’ profitability in no uncertain terms to interest tax deductibility, which he describes as “a giant tax loophole.”

“Any company can deduct the interest they pay on loans from their taxes, so if you buy a company with all this debt financing, then suddenly you’re basically not paying taxes anymore,” Kosman adds. “And the company can, in theory, then use that money to pay off its debt quickly. The reality is that’s not the way it typically plays out, but in theory that’s how it works.”

Theoretical or not, the tax/buyout link is vital for the P/E sector. “If you eliminated the tax deduction just for corporate takeovers, which would really only impact private equity firms, you would do a lot to make those firms unprofitable,” Kosman notes. “You would basically end the industry.”

That’s a much more attractive picture than the nauseating image of P/E firms standing in line with hands outstretched for a bailout a couple of years from now. I think I’d rather endure a bunch of 2012 end-of-the-world cataclysms than have to face that. ###