Scotsman Martin Creed has never had a solo show in Seattle before, so it must be dispensed with straightaway that he is a notorious artist. When he won Britain's Turner Prize in 2001 with a light turning on and off in an empty room—that's the entire work, and it can be installed in any room, using any light—another artist egged the walls and declared it a travesty against painting. It's fair to say Creed likes music better than painting, and sees it as a better model for art. "I see a gallery as a theater... and the experience of viewing as a live experience," he says. "Like a piece of music, the piece needs to be played or to be made in order to be experienced." This is the simplest explanation, if you must have one, for why a Chihuahua and an Irish wolfhound are in the gallery at Western Bridge.

When you enter, the wolfhound lopes up to greet you; she heard you coming. (This is like the opera: There are A and B casts to provide restful days off.) This work with the dogs is called Work No. 591, and it has, according to gallery director Eric Fredericksen, been staged only one other time, at a gallery in Los Angeles. All of Creed's pieces have numerical titles like that—the famous lights going on and off was Work No. 227, which should not be confused with Work No. 312, a lamp going on and off, which is installed in the back room at Western Bridge (in the form of a cheap-looking mid-century-modern knockoff lamp standing casually in a corner near one of the otherwise dark room's two only outlets).

In addition to the numerical title, Creed provides instructions, some written down and some not. Creed specifically called for an Irish wolfhound and a Chihuahua for Work No. 591, so Fredericksen placed an ad on Craigslist to find willing and able dogs (and dog owners). The dogs go home at the end of the day, and Creed also stipulated that the dogs should have food, water, and bedding—should not be mistreated—but this particular Chihuahua on this particular afternoon was hiding behind the toilet (in her tiny circular bed, which a very worried Fredericksen had placed there because the dog insisted on sitting behind the toilet) and snapped if you approached. Fredericksen worried that the dog was annoyed in particular by him, and that the dog he hired was doing the art wrong, which she was, in a way, since the two dogs are supposed to be in a gallery—an art space, specifically—and not its bathroom. In Los Angeles, reportedly, the dogs spent most of the time under the gallery desk, which also would be considered a kind of failure. But in this case, the dog essentially turned the bathroom into an art space. Visitors stood in the doorway to see the dog, which relaxed as long as she was in her own room, and sometimes the big dog stopped by. (An Irish wolfhound, when it stands on its back legs, is taller than an average person.)

The dogs threaten to become a gimmick that steals the show. But they aren't, and they don't. Instead, they simply demonstrate the usual limits of art—even when they're doing it wrong. Because of the dogs, perfect strangers introduced themselves and shared anecdotes: One woman, a museum curator who has recently moved to Seattle, described the Chihuahua approaching her from behind as she looked at one of the other Creed pieces in the show, a room half full of silver balloons (Work No. 360, better known by its tagline, "half the air in a given space"). She turned around, saw the Chihuahua's giant eyeballs (which, surely, are larger than the wolfhound's—a nice touch for a visual art experiment), and thought, "This is like the viewer personified. I'm not sure who's looking at whom here."

Dogs, Fredericksen explained to a group of high-school students who dropped by the show unannounced, make very bad abstract objects: If they're not sleeping or eating, they want to be with people. It's a little sad when the wolfhound wanders the gallery from visitor to visitor. She's confused by these temporary transactions, and noticing how temporary they are, you wonder about your own commitment to artworks and art experiences. Is it all just vicarious? If dogs are man's best friend, what's art—a lover on the side? Unmarriageable by definition?

At the entrance to the gallery is Work No. 990, a big black curtain over a big picture window, and it opens, then closes, over and over. It's neat to see the cover-up-and-reveal, and especially neat to see the people inside the gallery presented as a show as you leave. The curtain might also be taken as an implicit reference to the long-standing debate in academic circles over whether art is theater or objectness. Creed is seen by some as an extremist, but really he falls in the middle, again like a musician, using objects to create action. The objects do matter, and vary physically (unlike generic readymades), despite that they aren't being made or even specifically chosen by the artist.

Creed gives leeway to the work's owners and presenters, incorporating them as a midpoint between the traditional dualism of artwork and viewer (or the trinity of artist, artwork, and viewer). When Work No. 312 (a lamp turning on and off) was at the Henry Art Gallery a few years ago, it appeared as a gaudily tasseled thing standing in a skylit, tubelike room not much bigger than it; its previous incarnation at Western Bridge was as a night-light plugged into a low outlet on a wall in the ambient-lit opening room at the gallery. Now, in the back room, where the only light is the green EXIT sign, and represented by this stagy knockoff, it is ghostly and more narrative. It brings to mind the macabre Douglas Gordon piece 30 Seconds Text (1996), in which a bare lightbulb flashes for 30 seconds in a dark room so that you can read a story printed on the wall of a French scientist who, early in the 20th century, got eyelid responses from a guillotined man for 30 seconds after the head was separated from the body. Work No. 312 is nowhere near as dark or specific. But it is, as Fredericksen said he intended with his installation, seemingly very normal and also very abnormal. All of Creed's Works—they do rather than are—want to inhabit these opposite states at once. Which makes the gallery's title for the show, Open/Closed, Big/Small, Full/Empty, On/Off, perfect, even if the Chihuahua is hiding, or the silver-balloon room is just okay.