IT'S BEEN EIGHT YEARS between my sister's sophomore year in college and mine, eight years between John Kennedy's death and today, eight years between the first devastating blow to the idealism of the early '60's and a time when that idealism seems to college sophomores perhaps inspiring, probably naive, and, at the very least, anachronistic.

My sister, having passed the Elvis Presley Fan Club stage, played a lot of folk music in those days, music which captured the liberal self-righteousness that grew out of the freedom rides of Selma and Birmingham. "The answer," my sister and her friends were told, "is blowin' in the wind." "The times, they are a-changin'." The message of the music was: Don't give up; we're winning. Today may look bleak, but "see what tomorrow brings."

No group was more faithful to that message than Peter, Paul and Mary. Their own songs and the songs they sang by other people expressed a white, upper-middle class intellectual disgust over a nation embattled overseas and at war with its own people.

Peter, Paul, and Mary remained loyal to this commitment for a decade, through the marches on Washington and the '68 McCarthy campaign (Peter Yarrow is married to Mary Beth McCarthy). Last year, the three broke up, and last month's release of Peter Yarrow's solo album completed a series of debut solo efforts in which each has tried to project more clearly his or her individuality as an artist and performer.

THE RESULTS of these efforts are predictably mised, since the group's dissolving reflects a crisis in folk music itself. Folk music is the product of a country's and-or a people's spirit. When the common sentiment atrophies, very little substance remains for the folk artist to record. The alternatives are to reshape the spirit of the music as the spirit of the country changes, or to use the musical tradition to folk music to express more subjective, individual feelings usually in ballads and in love songs.

On these albums, Peter is the most aware of a folk tradition he has influenced and which he still wants to mold. He is a fine composer, and his intelligent lyrics bear witness to real feeling for the sound and rhythm of words used poetically. Paul's words are also subtle and engaging, although he is less lyrical. On his album he has opted for ballads instead of folk music that is geared to some prevailing national spirit. It is not entirely fair to compare Mary with the others since she does not write any of her own material. In recording songs by Elton John or by Rod McKuen. Mary has also been attracted to popular music, away from the folk sound of earlier years.

This drifting away from earlier material seems necessary, even when some of the new directions promise to be less consequential; attempts to reawaken the old are simply unsuccessful. "Give a Damn," a "talking song" on Paul and was a theme song for the Urban Coalition. It evokes, above all, a sense of deja vu. Its point is that arm-chair liberals are hypocrites--not an especially novel insight.

In the same way, a song called "Weave Me the Sunshine", on Peter, tries to recapture the group-singing enthusiasm associated with Peter's older "Day is Done." It does not work

THE CHIEF MISTAKE on Mary was the decision to compensate for the missing two voices with orchestrated arrangements. The freedom and direct emotional appeal of Mary's voice and the all-important sense of immediacy and earnestness of feeling in good folk music are muffled by unnecessary strings, bells, and percussion. One song with background orchestra does work. "The First Time Ever I Saw Your Face", but the loveliest cut on the album is the least ornate, the ballad called "I Guess He'd Rather Be in Colorado." Here, she uses her deeply expressive voice most creatively against a gentle and unobtrusive background arrangement.

Another problem with the album is the repertoire itself. John Denver writes pretty songs but they are not exceptional in any sense. Some lyrics and music on the album suggest other songs which convey identical sentiments more melodically or more eloquently. Paul Simon's "Song for the Asking" is done with appropriate warmth, but Paul Simon does it just as well. One song, McKuen's, relies entirely on Mary's voice, the album's one saving grace.

Paul's performance is similarly the chief virtue on Paul and. He sings Arlo Guthrie's "Gabriel's Mother's Hiway Ballad No. 16 Blues" better than Guthrie does, and "The Wedding Song," whose writer is unnamed, is a delicate and truly meaningful love song.

Of Paul's own songs, "Tiger," which talks about cleansing the spirit through faith, and "Hey Sad Sack," a ballad, are the most memorable. "Been on the Road Too Long" is energetic and catchy, but the other songs, even when pretty or genuinely interesting, are not especially exciting. The drive of the performance generally outclasses the material itself. Paul, like Mary, has a superb voice. A fine folk guitarist, he has had enough sense to keep his voice out in front of back-up instruments.

PETER'S ALBUM is the best of the three. He combines the intelligence of Paul's work with a greater simplicity of composition. Mary's voice is as good as Joan Baez's or Judy Collins's, but Peter's tenor is uncomparable. His voice is remarkably agile and constently full over his entire range. The delicacy of his singing matches the gentleness of his guitar, and he is backed, not by an orchestra, but by other singers who are capable of enhancing his music.

"Greenwood," which expands on a biblical verse, is hauntingly beautiful and expresses the torment Peter seems honestly to feel when faced with a decade's unsuccessful efforts to bring peace--

I've seen a thousand people kneel in silence.