Trillion-dollar question

How much debt is too much - particularly if Uncle Sam is the debtor? That question deserves far more serious attention than it has been getting in the Senate the past few days, as that legislative body entered into a feisty discussion over whether or not to lift the US debt ceiling, as requested by the Reagan administration. The House had approved a $1.6 trillion ceiling earlier this year, rather than wait until the last minute to decide the debt issue - namely, just before the debt ceiling authority was set to expire.

On Monday the Senate refused to raise the ceiling.

For starters, the Senate - and House members, too - would seem on better ground in more closely following their own budget process, as spelled out in the Budget Act. That legislation sets deadlines by which lawmakers are supposed to act on the various budget proposals. At the end of the process, lawmakers are supposed to put together a formal budget for the next fiscal year. What is disturbing to many economists is that lawmakers have repeatedly failed to meet their own budget requirements during the past few years, instead using continuing budget resolutions to finance and operate a number of US government operations.

Many economists argue that if legislators would follow their own budget law more carefully, they would more quickly find ways to make economies in government - and, thus, hold down the size of the national debt itself. Last-minute posturing on the size of the debt is hardly the right way to run the government - let alone any well-managed business.

How much debt is too much? Economists differ. (That usually happens when two of them enter a room.) The debt numbers seem awesome. The current debt ceiling is - are you ready for this? - $1.389 trillion. And the debt has expanded enormously. It was a mere $16.9 billion back in President Hoover's first year, in 1929.

But those numbers are not entirely what they seem. As a percentage of total debt in the United States (that is, the federal debt compared with total credit-market debt owed by nonfinancial sectors of the economy), the US debt has actually been shrinking. At the end of World War II, the federal debt as a percentage of total debt was 70 percent. In recent years it has been around 18 percent of total debt.

It has also come down as a percentage of gross national product.

Back in 1954, under President Eisenhower, it was around 62 percent of GNP. It is now around 35 percent of GNP, although rising somewhat.

What is evident is that the interest payments on the debt are too high, now running more than $100 billion a year. That represents resources that could be used in other ways - from funding child nutrition programs, to better schooling, to mass transportation programs.

Earlier this year, the President's Private Sector Survey on Cost Control - the so-called ''Grace Commission'' - estimated that the US could save more than approach to government. Exploring ways of actually making the US government more efficient - and thus helping to hold down deficits, and, in turn, the size of the federal debt - might be far more productive than last-minute, end-of-the-year handwringings over the debt ceiling.