The New England Repertory Company has opened its fifth season with a complex of paradoxes. Most striking of them is the first production, Jean Ferguson Black's "Penny Wise." Despite compounded line muffing and faulty pacing, the Repertory Players manage to make refreshing entertainment of a trivial but sparkling comedy. What plot there is can be summed up as "triangle plus happy ending." The cast, except for a few outstanding Repertory regulars, is distressingly spotty.

Three young women rescue the evening on Joy Street. Catherine Whitfield, as the chatterboxy but clever Penny, cops the laurels. Her portrayal of an intelligent woman acting dumb is convincing where it could easily be fatiguing. The part of the other woman in her husband's life was assigned to pert and pretty Carol Wheeler, whose relaxed competence belies the alleged nervousness of amateur actresses. Helen Sanderson, as another other woman, trips several times in the first act, but recovers her poise before the damage becomes irreparable. The men are weak spots in the performance, except for John Rand '43, whose three-minute bit in the last act won an appreciative burst of applause.

Other paradoxes crop up in the Repertory Theatre's plans for the coming season. The company isn't repertory any more, for it will present stock for two weeks at a time. The group has announced that comedy will be the main fare this year, but contradicts its own rule by scheduling Eugene O'Neill's tragic "Outward Bound" as the next presentation.

If the tiny theatre between Scollay Square and Charles Street Station overcomes its early-season tenseness and returns to the higher standards of previous seasons, it should easily fill the converted stable which it grandly calls an "auditorium." The Playhouse isn't great drama, but the plays are consistently chosen from tested works. Both the triteness and the crowding of wartime movies can be avoided by dropping into Boston's only permanent amateur theatre.