The federal government reopened, but our fiscal worries are far from over. The bill that ended the shutdown only funds operations through Feb. 8 — which means that unless Democrats and Republicans can reach an agreement on appropriations by tomorrow, we’re looking at another shutdown in very short order.

It is, to put it mildly, a mess. But as with all sticky situations, it presents an opportunity to reflect on how we got here and why it’s so difficult to come to a solution.

There are two types of spending in the federal budget — mandatory spending and discretionary spending. Mandatory spending occurs when a statute is passed that requires money to be spent over the long run. This money never has to go through appropriations. One example of this is Social Security. Spending on Social Security is based on the benefits put forth in the act and the number of people who have applied for Social Security.

The largest spending categories in the federal budget are mandatory spending. President Trump’s 2018 fiscal year budget estimated that mandatory spending will be $2.583 trillion. Net interest on the national debt, which must be paid to keep the federal government from defaulting, was estimated to be $316 billion. The spending that must be appropriated through the budget process for all the other federal programs, what is called discretionary spending, was estimated at $1.219 trillion, or 29 percent of the budget. In other words, if Congress decided not to pass any appropriations bills in any fiscal year, more than two-thirds of federal government spending would carry on anyway.

Nearly half of the discretionary spending is on national defense: $600 billion. This means that nondefense discretionary spending comes out to $618 billion. The original estimate of the budget — before the passage of the tax bill and the series of natural disasters of late 2017 — was $411 billion. A balanced budget would require axing a whopping two-thirds of all nondefense annual appropriations.

All these calculations should make one thing clear: We cannot realistically deal with federal deficits without grappling with mandatory spending. What’s more, we must start grappling with it soon. The Congressional Budget Office’s latest figures estimate that trillion-dollar federal deficits will return in the next four years — and these estimates were made prior to outlays for disaster aid and revenue cuts due to tax reform.

There are a number of ways to approach the problem. One would be to move Medicare and Medicaid to health savings accounts. Another would be to raise the retirement age for Social Security. Making substantive changes to mandatory spending will not be easy. But without modification, our deficit will only continue to spiral out of control, especially as the number of people qualifying for benefits under these programs continues to increase with the aging of the baby boomers.

It is easy to hype government shutdowns and vilify the opposing party, but now is the time for true debate on issues that have been ignored or avoided as too challenging to address. If we don’t have these conversations now, the federal debt will become so large that lenders will not allow Uncle Sam to pay off his maturing debt with new debt. When that day comes, we will know what a true government shutdown looks like.

Gary Wolfram is the William E. Simon Professor in Economics and Public Policy at Hillsdale College.

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