Sometimes it seems that the only way to make sense of the Bush administration is to imagine that it’s a vast experiment concocted by mad political scientists who want to see what happens if a nation systematically ignores everything we’ve learned over the past few centuries about how to make a modern government work.

Thus, the administration has abandoned the principle of a professional, nonpolitical civil service, stuffing agencies from FEMA to the Justice Department with unqualified cronies. Tax farming — giving individuals the right to collect taxes, in return for a share of the take — went out with the French Revolution; now the tax farmers are back.

And so are mercenaries, whom Machiavelli described as “useless and dangerous” more than four centuries ago.

As far as I can tell, America has never fought a war in which mercenaries made up a large part of the armed force. But in Iraq, they are so central to the effort that, as Peter W. Singer of the Brookings Institution points out in a new report, “the private military industry has suffered more losses in Iraq than the rest of the coalition of allied nations combined.”