PRESIDENT CARTER has drawn the only correct conclusion from Iran's defiance of his patient effort to negotiate the release of the hostages. The conclusion is that the effect at accommodation has failed and must be replaced by a punitive policy promising "increasingly heavy costs" to Iran if the hostages are not released promptly. And so it must. We assume that the president means what he says. Any hint that he does not would further endanger the hostages and would deepen doubts, in many places, about American constancy and reliability -- and about his leadership. We assume that by his announcement of a new policy he has nailed himself in.

The consensus is that the particular steps he announced on Monday will not by themselves cause Iran to free the hostages.Perhaps so. Those steps were meant only as the first in a progression. Many others are possible and are being discussed. Iranians, like everybody else, are curious to know if Jimmy Carter can stay the course. The combination of past American restraint and continuing Iranian intransigence suggests that he will have a broad measure of domestic and foreign support in doing so.

Interestingly, the intial steps drew contrary reactions in Tehran. Ayatollah Khomeini pronounced himself thrilled that the United States had given this boost to the Iranian revolution, which thrives on confrontation. President Bani-Sadr warned soberly that the United States was threatening the interests of the Iranian state. It is precisely the purpose of Mr. Carter's new policy, as we understood it, to act in a manner validating Mr. Bani-Sadr's judgment. That compels the United States to go beyond symbolism to measures that cut to the bone.

What Iranians have to decide is whether the political and phychic advantages of taunting the "satanic" United States outweigh the gathering costs. Iranians do live, after all, in a dangerous world. There is the Soviet Union. Then, attacks on oil pipelines and pumping stations are now reported. Are these the work of constituent ethnics with secession in mind? Are they the work of ambitious, formidably armed Iraq, with which Iran, irrationally, is pressing a rabid feud? Tehran acts as though its oil gave it immunity from conventional cares. Yet its exports are apparently down because of poor maintenance of the fields, inadequate capital expenditures and politically high pricing. Iranian oil production is now hardly a matter of urgent concern to anyone outside Iran.