“Hard Truths: The Art of Thornton Dial,” on display at the High Museum of Art through March 3, 2013, is the culmination of the 25-year rise to fame of an 84-year-old self-taught African-American artist whose origins, influences and originality all need to be reconsidered in a different intellectual framework. The categories of “folk art,” “contemporary art” and even “assemblage” and “conceptual art” do not serve us well any longer.

There is, for example, a book to be written about the relationship between the practice of 20th-century modernist assemblage and the folk practices of the regions in which artists started assembling objects: Central Europe in the case of the Dadaists, of course, but also rural and urban America, from California (where found-object assemblage flourished before Jasper Johns and Robert Rauschenberg made the practice famous) to the American South, where Rauschenberg grew up looking at African-American yard art, castoffs and discards arranged into provocative displays. (“Hard Truths” curators Joanne Cubbs’ and Eugene Metcalf’s catalog introduction cites a Newsweek story that claims Rauschenberg admitted this was an early experience.)

Rauschenberg wasn’t the only one to acknowledge vernacular influence. Rebecca Solnit notes, in her book Secret Exhibition: Six California Artists of the Cold War Era, that when curator William Seitz came to San Francisco in quest of art for the Museum of Modern Art’s 1961 “Art of Assemblage” show, artist Bruce Conner took him to look at arrangements in a Chinese laundry and an African-American junk store.

Such a book might help us make sense of the remarkable resemblance between Dial’s work and the Rauschenberg assemblage in the High’s “Fast Forward>>Modern Moments 1913-2013” show. It might also help us understand how Dial, a man practiced in carpentry, welding and a host of other skills, could have spent a lifetime creating found-object assemblages before being discovered in 1987 by another now-legendary black assemblage artist, Lonnie Holley, who brought Dial to the attention of the fabled art patron William Arnett.

It would also help us contextualize the slow ascent of Dial to global fame, from Roberta Griffin’s exhibitions at Kennesaw State University in the early 1990s to New York’s New Museum shortly thereafter to the present 20-year retrospective, via two 1996 Cultural Olympiad exhibitions in Atlanta and the 2000 Whitney Biennial. (The dazzlingly diverse directions of Dial’s work in the past decade and a half have been, to some degree, an effect of his exposure to new experiences and aspects of the world since his star has risen.)

At this point, Dial’s status as contemporary artist is secure and the environment out of which he arose is only a matter for scholarship. But that scholarship, which thus far has been deployed all too fragmentarily, is essential. Mr. Dial (I’ll explain the importance of that “Mr.” in a moment) is best thought of as fitting into the same categories of art as the wide range of contemporary artists with whom he is sometimes compared. The line of lynched crows (blackened rags) in “Green Pastures: The Birds That Didn’t Learn How to Fly,” for example, is visual shorthand for the past consequences of racism that would not be out of place in a theory-laden work by an art-school-educated artist.

Dial happens to be a conceptually minded, visually oriented intellectual who was deprived of formal education except for the practical skills that allowed him to both imagine and create elaborate objects that don’t fall apart after they have been constructed. Like the best artists of any cultures, including cultures that don’t call their object-makers “artists,” he has absorbed the visual and conceptual lessons of the examples available to him and used them to create works that have a powerful emotional and intellectual impact.

He did this despite a lifetime in which the honorific “Mr.” was usually denied to men of his social class and race. Hence the hardness of the truths he expresses symbolically in works that are frequently dark in emotional tone as well as palette. Abstract though it may appear, Dial’s work is intensely political in its own way, telling the story of the rise of African-Americans out of rural poverty and oppression to levels of status and recognition that can still remain more tenuous than the mainstream mythos is willing to admit.

Dial first came to public attention with densely pictorial works composed of oil and enamel paint on rope carpet, typically including the fluidly rendered image of a tiger as the symbol for black masculinity. Since then, his paintings and assemblage sculptures have incorporated found objects in ways that communicate both conceptually and viscerally: it takes only the patience to look closely for the viewer to be affected by the horrific details of the complex tangle of metal and mannequin heads in such works as “Victory in Iraq.”

Dial’s range of subject matter and visual strategies can be overwhelming. There are evocations of the oppressive quality of rural poverty that look like a hybrid of Italian arte povera’s use of commonplace objects and the pointed social satire of contemporary black artist David Hammons. An homage to “The Art of Alabama” juxtaposes a towering example of African-American yard art with the classical inheritance as represented by a statue of Pandora painted bright yellow (a statue that, incidentally, almost certainly comes from the popular genre of outdoor statuary also known as “yard art”).

A large part of Dial’s work is as dense and filled with darkness as the subject matter he tackles, from the economic and social implications of “Mercedes-Benz Comes to Alabama” and “Monument to the Minds of the Little Negro Steelworkers” to the aftermath of tragedies from mine disasters to 9/11. The tangles of cords and metal and plastic dolls (plus a few mummified animals) that symbolize the world’s entanglements aren’t the whole story, however. The metal-framework crosses and hanging scraps of cloth of “Crosses to Bear (Armageddon)” evoke the World Trade Center succinctly and sparely, in a sculpture that is a forerunner of Dial’s recent transition from vast, all-encompassing structures to assemblages in which a minimal number of objects have a maximum visual and emotional impact.

More importantly, there is a skeptically visionary side to Dial that is expressed in the complex exuberance of such works as “The Beginning of Life in the Yellow Jungle,” in which the dominant colors are vivid yellows and reds and symbols ranging from plastic flowers to a cloth-draped doll suggest the emergence of burgeoning life. The redemptive power of nature is set alongside the sacrifice of a black Christ in “The Dogwood Tree,” but by and large Dial’s symbols of spiritual liberation are more abstract, as in “Clouds Moving in the Sky, We Wake Up in Darkness and Look for Daylight,” where the title is as much a work of art as the elegantly composed work itself.

Dial’s accomplishment had to wend its way through the thickets of categories of folk art, fine art and still contested questions of race and class and respect that badly need to be rethought in less claustrophobic terms.