THE TWO BOMBS that went off in Washington the other morning delivered a message - but not the one intended by the bombers. According to the customary anonymous phone calls, they were the work of anti-Castro Cubans protesting human-rights violations or, in other version, the Panama Canal treaties. The real message was less confused. It was simply further notice that there are a few people around who have abandoned rational politics and have carried their causes into that bleak and spectral landscape lying beyond the boundaries of sanity.

The past week offered a variety of examples of the virus at work. In West Germany, radicals kidnapped and industralist, killing his driver and three policemen in the process. They are now trying to trade their prisoner for several terrorists held in German jails. In Holland, young Moluccans turned to violence again. Last spring, seven Moluccans with guns seized a train and a school. When their trial began this week other Moluccans rioted. Two schools were burned, and a policeman was shot and wounded.

Each of these instances took place in a country with democratic government in good working order at both the national and local levels. The people who turned to terror were the outsiders, too few and too wildly far from the majority to have any influence on legitimate politics. Usually they want things that no one can give them.

The Moluccan snipers want the Dutch government to obtain the independence of the islands from which their parents came. But the islands belong to Indonesia, which does not welcome advice from the Dutch on territorial matters. As for the German kidnappers, their political purposes are entangled in a wild rhetoric that strikes most other Germans as incomprehensible. The public response to them has chiefly been a discussion as to whether police protection is adequate. The Cuban bombers here in Washington - if in fact they are Cuban - have succeeded only in giving a crazy and disreputable air to the causes that they presumably wish to promote. At least the bombs did not injure anyone, although that was largely a matter of luck.

What can governments do about this kind of a challenge? No more, and no less, than Washington's law enforcement authorities did during the Hanafi siege and its aftermath. As long as the terrorists hold hostages, the authorities must bargain as best they can. When the hostages are released, the authorities must prosecute. When the terrorists are convicted, the sentences must be severe in proportion to the offenses - as, in the Hanafis' case, they were. Any minority, however tiny, is entitled to a hearing. But nobody has a right to endanger other people's lives in pursuit of his own claims on a government. A crime that claims a political purpose is no less a crime.