We encounter the same people on the freeways and in the supermarkets. But they don’t behave the same.

Pushing a shopping cart, people will make their way past others saying things like “oops” and “excuse me.” Pushing the gas pedal, they’re more likely to … well, no need now to spoil a nice morning, is there?

There’s a lesson here as we confront national anxieties about privacy. Many Americans are worried sick about the loss of privacy. This unease is particularly acute among those immersed in the Internet age. I’m afraid, however, that we’re confusing things in this discussion. We’re mistaking anonymity with privacy.

Privacy is the right to be left alone. Anonymity is the peculiar desire to be unknown and unaccountable, removed as it were, when we intersect with each other. Privacy is a matter of private behavior. Anonymity, whether achieved with an encasement of automotive sheet metal or by the use of a spurious e-mail identity, is a public concern.

Why do you want an anonymous identity on the Web? So you can avoid answering for what you say or do. Otherwise you wouldn’t need this. Last I looked, some Internet service providers offered subscribers the chance at five different identities, perfect for all but the most advanced cases of split personalities.

As daily experiences on the highways prove, there is a little beast in most of us, maybe all of us. In some, it rages hot. Anonymity, in the car or on the Internet highways, only encourages us to act on our worst impulses. Anonymous Web users can send death threats, invite illicit liaisons, masquerade and clutter the world with blather and slanders.

Here and there, a few plot crimes.

Not only are privacy and anonymity different things, they often conflict. Just look what a mess anonymous people make of public restrooms, spoiling things for the next person who needs a little privacy. Your ability to sound your way across the Web anonymously means that you can harass someone else and intrude on their time without being answerable. By what sensible measure can this be defined by a word so noble as “privacy”?

The creative geniuses who have given us the Web still insist that anonymity is one of its cornerstones. If so, the foundation is wormy. The longer that Web-heads insist on anonymity, the more the credibility and usefulness of their creation will be undermined. Already, one of the first lessons taught in middle-school computer labs is to regard everything on the Web as you might a puff adder apt to bite you at any moment.

But without a place to hide, you ask, what would happen to citizens in countries where freedom of speech is a crime? I’ll grant you the argument. But I still believe that revolutions are started by the brave, not the timid.

I acknowledge: My own hands are not entirely clean on these matters. The newspaper business trades on anonymous sources. I’ve relied on them myself, though I think they’ve become too commonplace. But such sources are not a cornerstone of the paper you hold in your hand. Anonymous sources are not presented to you without a writer and an institution putting their reputations on the line. Newspapers still answer to the laws of libel and to the free-market imperatives of trust.

None of this is the case with anonymity on the Web. So instead of worrying ourselves silly about ways to protect these few who are afraid to stand up for their words and actions, we should be going in the other direction: making it harder to be anonymous, marginalizing those who try. We may never humanize the automobile, but we can the future by tearing down those barriers that shield us from each other and tempt us to be our worst.