THE ACCOUNTS of the Marcos family's finances raise an interesting question about foreign debts. For years Ferdinand Marcos, his wife, Imelda, their relatives and their clients plundered the Philippine economy and, on a massive scale, transferred their booty abroad. At the point at which President Corazon Aquino's government came to power, the foreign debt of the Philippines stood at about $26 billion. How much of that is properly the debt of the Philippine state and how much of it is the debt of the exiled Mr. Marcos and his extended family? Is there a way to distinguish between the debts the Philippine people are morally obliged to repay and those that ought to be assigned to the former president?

The answer begins with the distinction between public and private debt. Of the $26 billion, about two- thirds was loaned to public authorities or was guaranteed by them. One-third is money loaned to private companies or individuals. Some of those borrowers are perfectly legitimate businessmen. But no one ought to be terribly surprised to learn that some of those private borrowers were shell corporations used simply to raise money and ship it out of the country.

To recover these loans to private businesses is the responsibility of the banks that made them, and no one else. A bank that makes a bum loan in Maryland can't ask the government of the United States to make it good. Neither can banks properly ask the government of the Philippines to make good the loans that they unwisely made to spurious businesses there. If a borrower turns out not to be a legitimate business and to have no assets in the Philippines, it's up to the banks to chase their money to its present resting places in the United States and Europe. The Philippine taxpayer has no obligation there.

The public loans are going to be harder to sort out. They clearly belong to the broad category of responsibilities that one government inherits from another, even when the earlier government was corrupt and the present one is not. While some of the borrowed money may have been stolen, some of it built roads and sewers and other facilities that continue to serve the public. A country has to regard its undertakings as binding. That's one of the characteristics that distinguish a nation from a mere crowd of people.

But the new government has important weapons. Where the new government can prove that money was stolen, and can trace it abroad, it can go into the courts of foreign countries to recover the fugitive millions. As it begins that process, it is entitled to the vigorous cooperation of American law- enforcement and banking authorities. The United States has promised Mr. Marcos and his party a safe refuge. It has not made any promises regarding assistance in grand larceny.