We don’t know how the government-shutdown fight will end. We only know that all the players will come out looking bad. So why are they battling?

The federal budget for fiscal 2019 is $4.407 trillion. President Trump wants $5 billion ($0.005 trillion) for more miles of wall along the border with Mexico. Democrats don’t want to spend a dime on the wall, but Senate Minority Leader Chuck Schumer has countered by offering $1.6 billion (less than $0.002 trillion) for border security.

Mr....