Two years after the accident at the Unit 2 nuclear reactor at Three Mile Island, a suit was filed to prevent the restart of the other, undamaged reactor. The argument was not that this reactor was a health hazard. The Nuclear Regulatory Commission had produced 22,000 pages of hearing transcripts to determine that it was not.

The argument instead was that people believed it was dangerous. Thus if TMI 1 were reopened, it might produce "intense anxiety" ("tension and fear, accompanied by physical disorders including skin rashes, aggravated ulcers, and skeletal and muscular problems"), and that would be a hazard to the surrounding communities.

A novel idea. Something is safe, but because people think it is dangerous, that makes it, well, (psychologically) unsafe. Perception is reality. The Supreme Court, however, was unimpressed with this novelty. It ruled, unanimously, that the NRC did not have to consider imaginary effects.

Fear is undoubtedly an unpleasant state, but in itself it does not create actionable claims. If it did, the line of litigants invoking such claims would be endless. Is there anything, after all, that people do not irrationally fear? If a groundless fear is enough to endow one with legal rights, then there is no piece of nonsense that cannot result in yet another claim upon others. Your neighbor has a dog. The dog is harmless. But you are afraid of dogs anyway. Can you impound the dog?

In the case of Three Mile Island, the Reagan Justice Department argued no. Now, another year, another place, and another piece of nonsense. The hysteria this time is not about gamma rays but about AIDS, the irradiated irrationality of the '80s.

The Justice Department has considered again the question of whether perception is ir,4p reality. It issued a ruling this week on what kind of discrimination is permissible against AIDS victims. The Rehabilitation Act of 1973 prohibits discrimination on the basis of handicap. Justice XR decided that an employer may not fire an AIDS victim if the employer is concerned about the "disabling effect of AIDS." But he may fire the victim if he is concerned about the contagious effects of AIDS.

Of course, in the work place there are no contagious effects. You have about as much chance of catching AIDS in the work place as you do of catching cancer or multiple sclerosis. So: your employee has AIDS or cancer or MS. The employee is harmless. But you are afraid of him anyway. Can you fire him? Says Justice, yes.

The immediate effect of this ruling will be to permit AIDS firings left and right. Is there an easier claim than the claim of irrational fear? The more general effect is to debase the idea underlying the antidiscrimination laws. The whole point of such laws is to say this: it may indeed cause you psychological distress to mix with others whom you irrationally dislike or fear. Too bad. The state has decided that these particular prejudices are destructive and irrational. Therefore the state will prohibit you -- even in "private-sector" transactions such as hiring or firing or serving people in your own luncheonette -- from acting upon your groundless prejudices.

The point of the Rehabilitation Act was to add another class of irrationality -- irrationality about the disabled -- to the catalogue of those the state will no longer countenance. Now comes Justice, in essence, to add: " -- except for one category of irrationality, fear of contagion. The state will permit you to fire disabled people on that account."

Even as a piece of reasoning, this casuistry fails. After all, why in general do people shrink from (and end up discriminating against) disability if not from fear of contagion? Moreover, if contagion were really the problem, private employers would not have to worry about it at all. The state can handle that. It has more sweeping powers against people with serious contagious diseases than it does against criminals. If you are innocent of all sin but have TB, the government can lock you away.

The problem of AIDS in the work place is not contagion. It is, as someone well acquainted with disability once said, fear itself. Fear itself does not deserve special protection in our public life.

There is no greater intellectual laziness than the proposition that perception is reality. The last place that Orwellian slogan ought to find refuge is in the law. The whole point of the law is to determine which perceptions are real and which aren't, and to give legal standing to one and not the other.

It does not matter if people think you murdered. If you didn't, you don't go to jail. It does not matter if people think TMI 1 is dangerous. If it isn't, it stays open. It should not matter if people think you can get AIDS in the Xerox room. You can't. Ignorance is a cause of discrimination. It is not a justification for it.