The WSJ on the practicality of taxing the rich:

A dominant theme of President Obama's budget speech last Wednesday was that our fiscal problems would vanish if only the wealthiest Americans were asked "to pay a little more." Since he's asking, imagine that instead of proposing to raise the top income tax rate well north of 40%, the President decided to go all the way to 100%...

Consider the Internal Revenue Service's income tax statistics for 2008, the latest year for which data are available. The top 1% of taxpayers—those with salaries, dividends and capital gains roughly above about $380,000—paid 38% of taxes. But assume that tax policy confiscated all the taxable income of all the "millionaires and billionaires" Mr. Obama singled out. That yields merely about $938 billion, which is sand on the beach amid the $4 trillion White House budget, a $1.65 trillion deficit, and spending at 25% as a share of the economy, a post-World War II record.

In 2005 the top 5% earned over $145,000. If you took all the income of people over $200,000, it would yield about $1.89 trillion, enough revenue to cover the 2012 bill for Medicare, Medicaid and Social Security—but not the same bill in 2016, as the costs of those entitlements are expected to grow rapidly. The rich, in short, aren't nearly rich enough to finance Mr. Obama's entitlement state ambitions—even before his health-care plan kicks in.