DUALITY, SQUARED, is on display at G Fine Art, where not just twos, but two different kinds of twos are put into play by artists Jose Ruiz and Beat Streuli.

Ruiz, a New York artist with ties to the District (from having recently lived here and from his ongoing membership in the Washington-based art collective Decatur Blue), is interested in many flavors of polarity: presence and absence, male and female, linkage and separation, pictures and text (or, for that matter, text and subtext), making and unmaking, haves and have-nots, and culture and subculture. The centerpiece of his exhibition, called "Underwriting," is a two-channel video, "Ghost Writing and Minimalist Graffiti." On one side, an all-black-clad tagger (Washington artist Kelly Towles) spray paints a black design, incorporating his signature, on a white wall. It takes all of 70 seconds, and he's out of there. On the other side, an all-white-clad figure (Ruiz himself) goes over the same drawing Towles has just made with a can of white spray paint, painstakingly obliterating the art that has just been made with stroke after stroke of whitewash until all that is left is a shadowy "ghost" of the original mark.

The whole eradication procedure takes about five minutes, during which time Mr. Clean's on-screen neighbor has made and remade the same drawing several times over.

The riff, of course, on Robert Rauschenberg's "Erased de Kooning Drawing," is obvious. Ruiz, however, takes that conceptual artwork -- which questioned the notion of authorship and the preeminence of the maker -- one step further, seeing as it is Towles's drawing, and not Ruiz's erasure, that seems to win out here, even in its undrawn state.

Other photographic works in the small show depict similar push-me/pull-you dynamics. A ski-masked man in a pinstriped suit reads the New York Times Arts and Business sections, from which all the pictures have been excised. A man and a woman's hands, locked in what used to be called Chinese handcuffs, are seen from two sides, with and without wedding bands, and variously tattooed with the words "I did" and "Did I."

Unlike Ruiz's "Ghost Writing," however, there is a kind of palindromic equilibrium to these works, a balance of yin and yang -- businessman and terrorist, art and money, marriage and divorce -- that creates tension without release. For every action, the artist seems to be saying with these pieces, there is an equal and opposite reaction; for every interpretation, a perfectly valid reinterpretation. It creates a kind of perpetual stasis from which there is no exit.

The work of Swiss-born photographer Beat Streuli is more tightly focused. While the title of his show, "NY-LA," suggests a possible fascination with differences between, say, East and West Coast lifestyles, the artist's subject is more precisely the difference between the observer and the observed. Known for his deadpan street photography of pedestrians, Streuli here presents two large C-prints of New York passersby (both seen in the 2002 Hirshhorn Museum and Sculpture Garden exhibition "Open City: Street Photographs Since 1950") along with video projections featuring strollers on Venice Beach and a kind of two-screen slide show of more New Yorkers.

The banality of Streuli's pictures is, at first, overwhelming. Still, the longer you spend time with them, the more you start to see that what Streuli is most concerned with is not, in fact, what can or cannot be seen -- not a lot, frankly -- but the complex, shifting interplay between the act of watching and the act of being watched. Particularly in the artist's "Venice Beach 09-20-03, I and II," there's not just the element of the voyeur, but the stalker, at work, as Streuli doesn't just set up a stationary camera to capture subjects walking by, but actually spies on them in slow-mo tracking shots.

The way these subjects interact (or don't) -- there's often two or more people in the frame -- is as important to Streuli as the way they present themselves to (or choose to ignore) the photographer. We, of course, may identify with either the looker or the looked-at, which affords a kind of comfortable anonymity that becomes increasingly uncomfortable the longer we're not sure which side of the camera is the safest place to be.

As many will no doubt point out, the answer to this question -- and to Ruiz's either-or conundrums -- may be some third option that neither artist is willing to explore, or to admit exists.

As it has been said, there are two types of people in the world: those who believe that there are two types of people in the world and those who don't.

JOSE RUIZ: UNDERWRITING AND BEAT STREULI: NY-LA -- Through July 16 at G Fine Art, 1515 14th St. NW (Metro: Dupont Circle). 202-462-1601. www.gfineartdc.com. Open Tuesday-Saturday 11 to 6. Free.

"Visual Coverage 1," by Jose Ruiz, shows a masked man in a suit reading the New York Times with its photos cut out.Beat Streuli's seemingly banal photos of pedestrians, such as "New York 2000," are complex studies of observing and being observed. "Did-I?" in Jose Ruiz's "Underwriting" exhibit at G Fine Art.