In ways that might be considered as ironic as they are unexpected, art brut, the related field of outsider art, and the even broader, related genre category that is known primarily in the United States as “self-taught art” have all become victims of their collective success. (Practically speaking, they all tend to be referred to using the umbrella term “outsider art.”) Today, these art forms have become more familiar—and perhaps also more popular—than ever.

With her colorful wigs, bug-eyed gaze and paintings, sculptures, and clothes covered with swarms of her signature polka dots, “infinity net” patterns, or phallic-shaped protrusions, the Japanese-born artist Yayoi Kusama has become one of the most visible figures on today’s international art scene.

Although Martha Wilson, who is based in New York, is best known as an alternative-museum founder, cultural activist, freedom of expression advocate, educator, and mother, she has also worked as an artist in her own right. As her recent solo exhibition at P.P.O.W. showed, through the years, her art-making and the thinking that has informed it have come a long way.

That modern art’s textbook history has been dominated by white Western males is old news to revisionist historians who have spent the past several decades trying to make room in it for other significant contributors to that story.

What is it about the expressive power of abstract art—especially abstract painting, whose ambiguity of meaning is one of its most definitive characteristics—that remains so alluring?

“Those are some good drinking songs,” the painter Valton Tyler observes, referring to some of country music’s classic, she-broke-my-heart, my-baby-left-me weepers that come streaming through his radio as he barrels down a six-lane highway amidst the urban sprawl of Garland, Texas.

At the age of 80, there are few places Gillian Jagger would rather be than in the seat of a Kubota L245 or a Massey Ferguson 135, two kinds of rugged tractors that can push or pull thousands of pounds of rock, dirt, debris, or lumber as easily as a determined frat boy can lift a 140-pound keg of beer.

Consider the lines with which Albert Camus opened The Myth of Sisyphus, his 1942 meditation on what he called the inescapable absurdity of human life: “There is but one truly serious philosophical problem,” he wrote, “and that is suicide … what is called a reason for living is also an excellent reason for dying.”