Radical ideas are on the boil in the folk-art world, and this record of a 1977 conference at the Winterthur Museum is the place to find them. Leading off is Beatrix T. Rumford's reprise of the aesthetic discovery of American folk art in the early 1920s (by modern artists who valued its ""abstract qualities""), and its collection and exhibition--culminating in the swank 1974 Whitney show. But succeeding articles, even as they deal with local documentation (in Michigan as a whole; among Norwegian-Americans and Pennsylvania Germans), shift emphasis to the social context--the object less as art than as artifact; and Lonn W. Taylor's fascinating piece on the rejection of traditional folk culture by Texas Germans breaks out of the ethnographic mold too, advising skepticism toward ""examples of ethnic 'folk survivals.'"" Still, John Michael Vlach performs a service in identifying forms of African material culture--as against music, dance, storytelling--which survived in the New World. Thereafter, the going is largely theoretical; and some of it is indeed heavy-going as one after another contributor--including art historian George Kubler and anthropologists Joannes Fabian and Ilona Szombati-Fabian--seeks to define folk art in terms of what it signifies. With the Fabians, we are into semiotics (""the transformation of human experience into shared significations""); with architectural historian Michael Owen Jones, we are into behaviorism (""specific events in which certain behavior is manifested""), and away from tradition and culture altogether. Kenneth L. Ames, more catholic, suggests multiple ""avenues of inquiry."" But the winner here may be Roger L. Welsch, who maintains that all present, faced with a group of objects, ""would agree on which were folk art""; and then he asks us to consider, as folk art, Dannebrog, Nebraska's magnificent maple--each fall the focus of ""resonance and reverberation"" in that barebones community. For those with a serious interest, a new--and unorthodox--basic text.