IN ITS SECOND flight from reason -- and from stands it has previously taken -- in as many days, the House voted last week to permit military courts to impose the death penalty on persons convicted of espionage in peacetime. The first response of some Americans may be to cheer this move as a useful deterrent and proper punishment for what all will agree is a dastardly crime. The second response, we hope, will be more cautious and less approving. Congress should have second thoughts too.

Legislators might begin by asking themselves whether the death penalty is likely to be much of a deterrent in such cases. Even if it is extended to civilian courts, it's not likely to be used in peacetime except in the most extreme of cases. Moreover, from what we know of the individuals accused in recent spy cases, the punishments they risked under current law -- lengthy prison terms -- were out of proportion to the rewards they are reported to have received. The remote possibility of a death penalty is not likely to shift the balance in any scales of deterrence.

What instituting the death penalty does do is to degrade the society that seeks to impose it. In wartime, when the nation calls on young men knowing that some large number of them will die, the imposition of the death penalty is perhaps understandable. In peacetime, in a society that prides itself on its civility and decency, it is not. The time is past when a civilized country used torture as a punishment. The time should be past when the U.S. government puts convicted defendants to death.

The additional danger here is that the House, in its successive votes for the death penalty and for authorizing lie-detector tests will get or convey the impression that it has done something useful to protect secrets against spying. More likely, it has diverted attention from the desperately important business of 1)separating secrets that genuinely need protection from the mass of material that is classified and 2)monitoring individuals who actually have access to those secrets. The House's response so far has been, in the words of Rep. Don Edwards (D-Calif.), "hysteria." It needs to get serious about this most serious business.