In 1952, when McCarthyism was at its height, Supreme Court Justice William O. Douglas labeled the investigative techniques of the junior senator from Wisconsin “guilt by association” (Alder v. Board of Education). Douglas added that McCarthyite tactics were “repugnant to our society” because, despite the absence of any overt wrongdoing, the pasts of those attacked were “combed for signs of disloyalty” and for utterances that might be read as “clues to dangerous thoughts.”

More than a half century later, “McCarthyism” was joined in the lexicon by “Swiftboating,” the art of the smear campaign mounted with the intention not of documenting a wrong, but of covering the victim with slime enough to cast doubt on his or her integrity. Now, in 2008, after a primary season increasingly marked by dirty pool and low blows, “McCarthyism” and “Swiftboating” have come together in a particularly lethal and despicable form. I refer to the startling revelation — proclaimed from the housetops by both the Clinton and McCain campaigns — that Barack Obama ate dinner at William Ayers’s house, served with him on a board and was the honored guest at a reception he organized.

Confession time. I too have eaten dinner at Bill Ayers’s house (more than once), and have served with him on a committee, and he was one of those who recruited my wife and me at a reception when we were considering positions at the University of Illinois, Chicago. Moreover, I have had Bill and his wife Bernardine Dohrn to my apartment, was a guest lecturer in a course he taught and joined in a (successful) effort to persuade him to stay at UIC and say no to an offer from Harvard. Of course, I’m not running for anything, but I do write for The New York Times and, who knows, this association with former fugitive members of the Weathermen might be enough in the eyes of some to get me canned.

Did I conspire with Bill Ayers? Did I help him build bombs? Did I aid and abet his evasion (for a time) of justice? Not likely, given that at the time of the events that brought Ayers and Dohrn to public attention, I was a supporter of the Vietnam War. I haven’t asked him to absolve me of that sin (of which I have since repented), and he hasn’t asked me to forgive him for his (if he has any).

Indeed in all the time I spent with Ayers and Dohrn, politics — present or past — never came up.

What did come up? To answer that question I have to introduce a word and concept that is somewhat out of fashion: the salon. A salon is a gathering in a private home where men and women from various walks of life engage in conversation about any number of things, including literature, business, fashion, films, education and philosophy. Ayers and Dohrn did not call their gatherings salons, but that’s what they were; large dinner parties (maybe 12-15), with guests coming and going, one conversation leading to another, no rules or obligations, except the obligation to be interesting and interested. The only thing I don’t remember was ideology, although since this was all going on in Hyde Park, there was the general and diffused ideology, vaguely liberal, that usually hangs over a university town.

Many of those attending these occasions no doubt knew something about their hosts’ past, but the matter was never discussed and why should it have been? We were there not because of what Ayers and Dohrn had done 40 years ago, but because of what they were doing at the moment.

Ayers is a longtime professor of education at UIC, nationally known for his prominence in the “small school” movement. Dohrn teaches at Northwestern Law School, where she directs a center for child and family justice. Both lend their skills and energies to community causes; both advise various agencies; together they have raised exemplary children and they have been devoted caretakers to aged parents. “Respectable” is too mild a word to describe the couple; rock-solid establishment would be more accurate. There was and is absolutely no reason for anyone who knows them to plead the fifth or declare, “I am not now nor have I ever been a friend of Bill’s and Bernardine’s.”

Least of all Barack Obama, who by his own account didn’t know them that well and is now being taken to task for having known them at all. Of course it would have required preternatural caution to avoid associating with anyone whose past deeds might prove embarrassing on the chance you decided to run for president someday. In an earlier column, I spoke of the illogic of holding a candidate accountable for things said or done by a supporter or an acquaintance. Now a candidate is being held accountable for things said and done four decades ago by people who happen to live in his upper middle class neighborhood.

Hillary Clinton and John McCain should know better. In fact, they do know better. To date, Clinton has played hardball, but hasn’t really fouled. I never saw anything wrong or inaccurate about her saying that Martin Luther King’s vision required a president’s action before it could be implemented, or Bill Clinton’s saying that Jesse Jackson won the South Carolina primary twice. He did, and if the implication was that Obama’s base constituency is African-American, that too was accurate and continues to be so.

As for her saying that all Obama had ever done was give a speech, she was being generous: he gave that speech against invading Iraq at a small event featuring other speakers (including Jackson); the local press coverage did not even mention him; and if this was, as his campaign claims, an act of courage, it was a singularly private one, maybe even a fairy tale. Clinton’s exaggerating the danger of her visit to Bosnia (most likely unintentional because, as she said, “I’m not dumb”) came a little closer to crossing a line, but didn’t. Re-telling a story (about a hospital’s refusal to treat an uninsured patient) that turned out not to be true was evidence of faulty campaign organization, not of deliberate duplicity.

But the literature the Clinton campaign is passing around about Obama and Ayers cannot be explained away or rationalized. It features bold heads proclaiming that Ayers doesn’t regret his Weathermen activities (what does that have to do with Obama? Are we required to repudiate things acquaintances of our have not said?), that Ayers contributed $200 to Obama’s senatorial campaign (do you take money only from people of whose every action you approve?), that Obama admired Ayers’s 1997 book on the juvenile justice system, that Ayers and Obama participated on a panel examining the role of intellectuals in public life. That subversive event was sponsored by The Center for Public Intellectuals, an organization that also sponsored an evening conversation (moderated by me) between those notorious radicals Richard Rorty and Judge Richard Posner (also a neighbor of Ayers’s; maybe the Federalist Society should expel him).

I don’t see any crimes or even misdemeanors in any of this. I do see civic activism and a concern for the welfare of children. The suggestion that something sinister was transpiring on those occasions is backed up by nothing except the four-alarm-bell typography that accompanies this list of entirely innocent, and even praiseworthy, actions.

As for Senator McCain, in 2004 he repudiated the Swiftboat attacks against fellow veteran John Kerry, but this time around he’s joining in, and if Obama gets the nomination, it seems that the Arizona senator will be playing the Ayers card. Of course, McCain knows a little about baseless accusations and innuendos, given his experience in South Carolina in 2000. And in case he has forgotten what it feels like, he may soon be reminded; for there’s a story abroad on the Internet that says that rather than being a heroic, tortured prisoner of war, McCain was a collaborator who traded information for a comfortable apartment serviced by maids who were really prostitutes. I don’t believe it for a second, just as I am sure that Senators McCain and Clinton don’t really believe that Obama condones setting bombs or supports a radical agenda that was pursued (as he has said) when he was eight years old.

The difference is that I feel a little dirty just for having repeated a scurrilous rumor even as I rejected it. Apparently Obama’s two opponents have no such qualms and are happily retailing, and wallowing in, the dirt.