We should not have hijacked the plane of a friendly nation, especially after that nation, Egypt, had pulled a few of our chestnuts out of the fire.

It is fairly thrilling, of course, that we now have the prospect of four known terrorists being brought to justice, for a change, especially since the murder of an innocent American on the cruise ship.

But even in my own excitement I try to require myself to use words as clearly as I can and to think as straight as I can manage, and I see disastrous flaws in the argument advanced by our officials and widely accepted by citizens. Tell me if I have got the argument right:

It is too bad we had to interfere -- that is, to intercept and persuade the pilot to land at a place of our choosing -- with the Egyptian plane, especially since the president of Egypt performed some service for us in getting the thugs off the ship so we could capture them and bring them to justice.

But then it is also too bad -- and is intolerable -- that time after time innocent Americans are held hostage by terrorists and subject in many cases to kidnaping or murder at terrorist hands. In this case we had the rare chance to capture or control the landing of the terrorists and we were right to take it. We were right, first of all, because it is necessary to send a message to terrorists that they cannot escape responsibility for their crimes, and we were right again because the decent people of the world, not just in America, need to see that terrorists cannot get away with murder.

Now that seems a fair summary of the president's position, and anybody who takes exception to it (though he be communist or fascist or both or worse) has the task of showing where that seemingly good argument falls apart, and why it is dead wrong.

First, was the interception of a friendly nation's plane a hijacking? What is a hijacking, anyway? The gist of the crime is the seizing by force and violence of an aircraft or ship, contrary to the wishes of the owners or the authorized operators of the vessel, and endangering the safety or comfort or convenience of the passengers. To see for yourself whether you'd call the interception a hijacking, simply substitute an American plane for the Egyptian one, and instead of our Navy fighters just substitute fighter planes of Japan, France, Israel or any other of our allies. There would not then be any pussyfooting about "interception."

Then the question arises, is a hijacking not a crime if you call it something else? Or is it not a crime when we do it, but only when others do?

Is it sometimes a crime but not always, especially if there are sound political reasons for it?

Then there is the "message to terrorists" that their crimes will not go unpunished. This is very comforting.

Terrorists will now know, and will see with their own eyes, what happens to terrorists who get caught murdering innocent people. And this, I gather, will stun them. They seized ships and blew up Marines and did all manner of outrageous things but never would have done any of those things if they had reason to believe they would be caught and punished. The terrorist who drove a dynamite truck into an American military post would never have done so if he had got the message beforehand that he would be punished. (He was blown up by his own dynamite, of course, but that was because it never occurred to him he would get hurt.)

Quiet and prudent negotiation may reduce the effect of dreadful terrorism, but will never satisfy anybody's desire for true justice. Presidents other than Reagan have wrestled with it, sometimes without applause. But only two policies hold much promise for ending the terrorist acts themselves. Terrorists will be deterred if they gain nothing from terrorism. If, when they hold Americans hostage, they see that the American state will not meet their demands, even if they murder all the Americans, then they will gain nothing from their crimes. As it is now, they risk their lives knowing we will yield rather than let them kill their American hostages.

The other deterrent to terrorism is to remove the desire of the terrorists to kill innocent people. The English, for example, do not kidnap or murder Americans, mainly because they have nothing to gain, but others think they do.

Back to the present case, let's assume the cruise ship terrorists are convicted and severely punished. Well, there are four terrorists we won't have to worry about further. Does it also mean that if new terrorists capture a plane and threaten to kill Americans that we will now have the power to save both American lives and American pride? Or do we just refer any future terrorists to our impressive message of October 1985?

While we're messaging, people other than terrorists get the news as well. One of our messages is that hijacking is not hijacking if we ourselves do it for a noble and politically understandable reason. Another message is to that relatively minor state called Egypt. "We rely on you to get the thugs off the ship because we don't know how to, but chances are you will negotiate in some wimpy way that lets the bastards go free, but don't worry about that because we will then intercept your plane and get 'em."

What happens if terrorists capture Americans again (there is always somebody who doesn't get the message) and we ask Egypt again for cooperation? Will the Egyptians say:

"We got the thugs off the ship the last time, removing the threat of death to the Americans on board. We negotiated them off the ship as well as we could, but of course you were disappointed with the result. Besides, you are the great experts on the handling of terrorism. Get them off yourself, the same way you got rid of them in Iran and Lebanon and the TWA plane. And lotsa luck."