President Trump has just announced exactly the right policy to deal with coronavirus interruptions to the economy — well, announced he’s thinking about it. Cutting payroll taxes is the best way to handle it, as even John Maynard Keynes himself pointed out.

Think back to what the central contention of Keynesian macroeconomics is. Something goes wrong in the economy (something being any one of a long, long list of possibilities), and there’s not enough demand out there. The economy can get stuck at this less-than-maximum-potential level of output simply because no one’s spending the cash. So, government can and should expand demand by increasing the budget deficit. That means it should spend more than it collects in taxes, filling the gap with borrowing. This stimulates consumption, perks up production, and we leap back to being as well off as we can be.