So, have you heard the one about the trillion-dollar coin? It may sound like a joke. But if we aren’t ready to mint that coin or take some equivalent action, the joke will be on us — and a very sick joke it will be, too.

Let’s talk for a minute about the vile absurdity of the debt-ceiling confrontation.

Under the Constitution, fiscal decisions rest with Congress, which passes laws specifying tax rates and establishing spending programs. If the revenue brought in by those legally established tax rates falls short of the costs of those legally established programs, the Treasury Department normally borrows the difference.

Lately, revenue has fallen far short of spending, mainly because of the depressed state of the economy. If you don’t like this, there’s a simple remedy: demand that Congress raise taxes or cut back on spending. And if you’re frustrated by Congress’s failure to act, well, democracy means that you can’t always get what you want.

Where does the debt ceiling fit into all this? Actually, it doesn’t. Since Congress already determines revenue and spending, and hence the amount the Treasury needs to borrow, we shouldn’t need another vote empowering that borrowing. But for historical reasons any increase in federal debt must be approved by yet another vote. And now Republicans in the House are threatening to deny that approval unless President Obama makes major policy concessions.