“Sculpture is what you bump into when you back up to see a painting,” Barnett Newman once joked. But given how installation art has dulled the formal “punch” of discrete sculpture, that jab seems quaint rather than derisive today.

In contrast, both the minimalist sculptor John McCracken and the eclectic Rita McBride approach sculpture through distinctly conventional issues in their respective solo shows at David Zwirner and Alexander and Bonin. From diametrically opposed ends, each affirms the space-altering potential of sculptural form, and in doing so, sculpture’s ability to transcend its material.

If one is unlikely to knock into conventional sculpture anymore — but rather stumble onto what’s called its “expanded field” — overlooked in the theatrical emphasis of installation art is precisely this ancient but enduring aspect, captured in the myths of Prometheus and Pygmalion, of Adam and Don Giovanni.

A lesser-known though important figure in the history of minimalism, Mr. McCracken has emphasized the physicality of sculpture and its apprehension by the viewer in his work since the mid-1960s — a set of concerns loosely referred to as “phenomenological.” The New Mexico-based artist’s sculptural language is roughly that of post and lintel, condensing form with the clarity of 18th-century Japanese painter Gibon Sengai, who could illustrate anything in the universe with only a triangle, a circle, or a square.

This distilled formal language is captured in Mr. McCracken’s best-known work, his “planks.” Rectangular, resin-covered plywood sculptures that are leaned against the wall, these are handcrafted and polished to a translucent, monochromatic surface. The effect is to make his sculptures simultaneously “content-less” yet filled with each viewer’s unique experience of color, space, and volume.

Mr. McCracken’s new work combines plank pieces with a series of large freestanding columns and an eight-part wall piece, all in nearly imperceptible gradations of reflective black. (There is also a separate column made of stainless-steel). These various abstract forms cover several possibilities of arranging sculpture in space; some are leaned or suspended on a wall, as in the Donald Judd-esque “Diamond,” while others have the weighty physicality of traditional statuary.

All share the issue of difference in repetition, treating particular objects as undifferentiated yet perceptibly distinct. In their various incarnations, the black forms affirm their physicality while also effacing their own presence. The reflective surfaces provide nothing but an extension or contraction of the viewer’s field of vision. When the gallery is empty, the sculptures act as black mirrors extending the space off into varying planes; when full, they create a dizzying reflection of the density around you.

Mr. McCracken’s new work also plays off a particular oddity of perception: the inevitability of perceiving things metaphorically even if experienced literally. So to the psychological game with infinity, color, and volume, Mr. McCracken adds a bit of geomancy. The nine large black columns that fill one of the galleries, with names like “Luster” and “Stardust,” seem to be arranged in a “ley line” nexus, the same that aligns ancient monuments, votive sculpture, and megaliths — among the earliest of all forms of sculpture.

Ms. McBride, who has made largescale installations, site-specific works, and discrete objects in a wide range of materials, uses a series of drafting templates, which she dubs “Tools for Sculpture,” to explore issues of function and form in her show, “Double to Watch, Triple to Help.”

This idiosyncratic subject matter is in keeping with her interest in the “blind-spots” of urban modernism, things like parking garages, awnings, and air-conditioning units. With an abiding interest in such vernacular architecture, Ms. McBride looks to everyday structures and prosaic design elements in her work, recasting them in often-surprising materials.

Her new sculptures, made from traditional materials like glass, steel, and bronze, turn to the functional and artisanal side of design, in the form of the tools we use to organize and create the spaces around us.

Consisting of oversized, near-kitsch replicas of the punched-out templates found on an architect’s draft table, the show turns simple abstract shapes used to render everything from a straight line to a complex electrical circuit into sculptural objects. Ms. McBride uses this degree of abstraction, seen in work like “French Curve Diptych,” an outline from which a mathematically complex object is easily composed, to reflect on how sculpture works.

The most obvious example is also the basic element of all sculpture: the setting of an object off in space. That is already suggested on a smaller scale by the templates themselves, since each circle or square represents a potential physical thing taking up a specific volume in the real world. Precision cut, Ms. McBride’s sculptures in fact bare the same industrial look as the objects they might represent on an architectural plan.

Ms. McBride’s work, like Mr. McCracken’s, also surveys how sculpture can be propped, leaned, or hung. In doing so, she turns functional things into sculptural objects, as Mr. Mc-Cracken turns simple forms into contemplative sculpture. Situating sculpture somewhere between landscape and architecture, both Mr. McCracken and Ms. McBride parse out the physical and poetic space that spectacle too often obscures.

McCracken until October 14 (533 W. 19th St., between Tenth and Eleventh avenues, 212-727-2070);

McBride until October 25 (132 Tenth Ave., between 18th and 19th streets, 212-367-7474).