It's considerably older than twenty years, and it wasn't written by a woman, but otherwise this describes the short story SHAWNA, Ltd by Barry Longyear, published in Asimov's in September 1979.
The story concerns a spaceship that was powered by philosophy, in detail:
SHAWN A — (Supraliminal Hegelian Absolutized World Neotranspatial
Amplifier), a device that amplifies the component of mind that creates
and alters reality. SHAWN A theory, rooted in the work of the early
idealistic philosophers, was first made practicable in 2134 by
physicistphilosopher Leonid Veggnitz, at which time it was first used
in transportation over multi-parsec distances (See: SHAWNA, Ltd. under
Space Lines, Commercial).
The philosophers on board indeed limber up by considering philosophical statements:
Wheeler faced to his front, stabbed several buttons set into his
chair's armrest. "Into first, then: objects depend on mind for
existence; objects have no meaning apart from the knower, and the
knower is mind; objects cannot exist apart from mind."
moving up through the gears until they reach:
"Ready for third, lads?" Nods all around. "Here we go, then: subject
and object are reciprocally dependent upon each other; there can be no
subject without an object and no object can exist without a subject;
complete reality is a unity of subject and object."
They arrive at their destination, but then face a crisis when one of the philosphers begins to pray, plunging them into "Hegelian Overdrive".
The complete text is available from the Internet Archive in Longyear's anthology, It came from Schenectady.