A little over a century ago, as the South Carolina convention was meeting in Charleston to vote for secession, James Louis Petigru, a native Charlestonian, was stopped by an out-of-owner who asked the way to the city insane asylum. "I don't know which insane asylum you're looking for," Petigru replied and, pointing to the building in which the convention was meeting, continued, "but the one with the most lunatics is right over there."

Today, the same scene could probably be repeated in Boston with only minor changes. In place of the South Carolina convention would be the Boston School Committee. With secession no longer an issue--at least for northern states--the crucial vote would concern the question of de facto segregation. And in the shoes of James L. Petigru would be his Virginian-born descendent, Thomas Fraser Pettigrew, associate professor of Social Psychology--whose course on racial prejudice and desegregation, Social Relations 134, has become the academic stronghold of the Harvard civil rights movement.

Like his ancestor, whom he calls, "my patron saint--the rest of the Pettigrews were real bastards"--Pettigrew is a rebel, and loves it. On the day he was to testify before the Boston School Committee on the psychological effects of school segregation, he told a class that he hoped Committeewoman Mrs. Louise Day Hicks would charge him with being an outside agitator.

"If she does, I'm going to stop the meeting and say, 'I want you to realize this is an historic moment. For years, Southern racists have been calling Northern liberals outside agitators. But this probably the first time that a Northern racist ever called a Southern liberal an outside agitator.'"

On another occasion, when Pettigrew had been doing research for several months at the University of Natal in South Africa, he was called to the office of a government official. "I'm sorry to have to inform that you are no longer welcome in the Union of South Africa," the official told him.

Swallowing a grin, Pettigrew replied earnestly, "Why sir, that's the biggest compliment I've ever recieved."

How does a Southerner become a civil rights enthusiast?

Born in Richmond, Va., in 1931, Thomas F. Pettigrew escaped the doctrine of racism from the start. "I was brought up by a Scottish grandmother who thought that all Americans--North or South, black or white--were crazy," he relates. "My father was a mild-mannered man, conservative but not racist, who came from the hills of West Virginia. It was a great combination.

"Very early, I knew Negroes who clued me in on what it was like to be a Negro. Whites have to be clued in by Negroes and in my case it was our Negro cook, Mildred Adams, who did the job.

"We were both Humphrey Bogart fans, Mildred and I, but the Richmond Theater had no section for Negroes, so she had to wait 18 months to see the new Bogart movie. I would come home and tell her about the picture as she did the laundry, and she would explain to me why she couldn't go.

"I thought it was absolute injustice that Mildred Adams couldn't see Humphery Bogart. One day I just refused to go into the theater when they wouldn't admit Mildred." Here, Pettigrew laughs. "My mother always used to say that was the first of the boycotts."

By the time he was 12, Pettigrew was having arguments over race with his teachers. "They used to send me to the principal because I maintained that Jefferson was a great liberal," he recalls. "Naturally, the opposition of my teachers just fed my convictions." At college at the University of Virginia, liberal professors further bostered his beliefs.

Pettigrew is one of those people for whom interests, beliefs, and career dovetailed perfectly. He describes his decision to major in psychology quite simply: "I've always been interested in race relations, but I never realized that you could study them." Graduating in 1952, he came to Harvard to study under Gordon W. Allport, and earned his doctorate in 1956. After teaching for a year at the University of North Carolina, he returned to Cambridge, where he has remained ever since.

Meanwhile, he picketed the Belmont Woolworth's in 1960 and taught Negro history in a freedom school during last June's school boycott. He also helped to found the Episcopal Society for Cultural and Racial Unity (ESCRU) and served as a consultant for several Southern school boards considering integration.

Of medium height with a graying crewcut, Pettigrew could easily pass for a junior executive--that is, until he opens his mouth. He speaks in slang, spiced with psychological and sociological jargon. (Someone is "scared as shatters;" de facto segregation is the "functional equivalent" of legal segregation.) His Southern drawl, clipped short after 12 years in the North, can be turned on and off at will, but generally a distinct trace of it clings to his words.

He speaks very quickly, slurring his words together. A great story-teller, he gets so excited about his tale that he fairly gurgles with delight, leaving sentences unfinished as he dashes for the punchline. Chuckling often as he speaks, he occasionally looses a loud, almost demonic laugh.

Although he plans to remain in the North for the rest of his life, Pettigrew retains an almost organic closeness to the South. "It's a stigma I can't get rid of" he says, "but then again I don't really want to. I love the damned South. That's why I spend my life studying it, writing about it and speaking on it. I feel responsible for it--that's the reason I can dislike Wallace with a kind of feeling that I can't work up for Mrs. Hicks. I share the blame for Wallace."

"We Southern liberals," he suggests fondly, "we've had a dream that the South will beat the North in race relations. In the South, Negros and whites share a religion and a culture--they've been there together for 14 generations. In the North, on the other hand, there's no unity; whites are afraid of the Negroes. We used to think that once we got over the hump of legal segregation, we'd be on our way.

"But now I'm beginning to get pessimistic. As quickly as a city is integrated, de facto segregation is setting in, We're going to have to fight through what the North is fighting through. The blooming days of Southern liberalism are not yet at hand."