We shouldn’t try to get corruption to zero because fighting corruption is costly. Think, for example, of government contracting, which mindlessly awards contracts to the low bidder, as if quality and reliability were irrelevant considerations. This sloppiness inevitably adds time and costs. Or the various requirements we impose on civil service workers to make sure that not one of them enjoys so much as a stray sandwich on the taxpayer dime … and thereby ensure that normal business practices, like sitting down for an inexpensive group meal to discuss something, are almost comically difficult to arrange. All these procedural rules make government less effective and more costly. My father, who was the head of a trade association for contractors on heavy infrastructure projects, estimates that adding federal money to a project adds about five years to its completion date.

There’s even more reason not to strive for zero corruption: Politics is the art of getting widely disparate factions to come to some sort of policy agreement, and “clean graft” greases those wheels. Now, calm down — I’m not advocating that we move to a full-on kleptocracy like Russia. What I’m suggesting is in attempting to root every last vestige of pork and patronage out of the system, we have inadvertently produced the partisan gridlock that we now decry. Anyone who thinks that this is a crazy statement should read Jonathan Rauch’s terrific new e-book, “Political Realism: How Hacks, Machines, Big Money, and Back-Room Deals Can Strengthen American Democracy.” At a trim 55 pages, it is a fast read, and at $0, it is the bargain of the century.

Among other insights, Rauch divides politics into two groups: amateurs and professionals. The amateurs are the high-minded folks we all admire, who pursue a single issue, or a narrow set of them, with purist zeal. The professionals are the ones we despise: party men and women who are primarily focused on winning elections and making deals so that they can win more elections. It’s a grubby business, this professional politics. But as Rauch points out, it’s also necessary to actually get things done. Left to their own devices, the activists will pursue total war rather than an unsatisfactory armistice, and the rest of us will be left to wander through the barren landscape they’ve shelled to pieces.

For a little more than a century, the amateurs have also been waging war on professional politics, with increasing success. Many of these successes, like the professional civil service, were good things. But fighting corruption offers decreasing returns. The more recent victories had high costs, and less certain benefits — or even a net cost.

Actually, I think the “professional” civil service is looking awfully corrupt today, itself.