COLUMBUS, Ohio, March 11 — Proponents of the intelligent-design movement, which challenges Darwin's primacy in the science classroom, argued for equal footing in the state's new teaching curriculum today, while critics warned that speculative theories of some ultimate agent underpinning evolution were the antithesis of true science.

Hundreds of people sat for more than two hours at a hearing on the issue by the State Board of Education, listening to abstruse arguments about the bacterial flagellum and the peppered moth before one of four clashing scholars finally used the G- word that had attracted the crowd in the first place.

"The real danger is in trying to put God in the gaps," said Dr. Lawrence Krauss, the physics chairman at Case Western Reserve University.

Dr. Krauss argued that while much remained to be discovered about natural selection, Darwin's theory had only grown in strength through decades of repeated experimentation and discovery that intelligent design had not been subjected to.

In contrast to the biblical literalism of creationists, proponents of intelligent design acknowledge that the earth is billions of years old and that organisms evolve over time. But they dispute that natural selection is the sole force of evolution, arguing that life is so complex that only some sort of intelligent designer, whether called God or something else, must be involved.

Members of the school board, which will vote this year on a new curriculum, the old one having come up for routine review, asked for the hearing today despite a strong endorsement of evolution teaching from the board's curriculum advisory panel.

"There are unanswered questions," Dr. Krauss conceded of evolution, even as he warned that intelligent-design proponents were trying to force "unanswerable questions" about some theoretical instigator of life onto a school curriculum properly limited to the rigorous proofs of science.

With equal fervor, Dr. Jonathan Wells, senior fellow at the Discovery Institute, a Seattle organization dedicated to alternative scientific theories, contended that there was enough valid challenge to Darwinian evolution to justify intelligent design's being ordered into the classroom curriculum — not as a religious doctrine, he maintained, but as a matter of "a growing scientific controversy."

"I'm not trying to tell you who's right and who's wrong here," Dr. Wells, a biologist and religious studies scholar, said in denying critics' accusation that the intelligent-design movement was a new approach, veiled in scientific trappings, to forcing theism into the public schools.

"Is the design that we all see real or merely an appearance?" Dr. Wells asked.

He argued that teachers should be entitled to plumb this question as a matter of intellectual fairness for their students, based on what he described as significant recent criticisms of neo-Darwinian theories about random mutations and the creation of new organisms.

Dr. Kenneth R. Miller, a biologist at Brown University, told the board that the state of "scientific controversy" being repeatedly claimed by the two speakers for intelligent design was nonexistent among the vast majority of scientists. Instead, he said, it was "propped up from outside the scientific community" in a move to pressure legislators and school officials to overrule the scientific mainstream.

One of the best lessons a teacher can offer students is to "let them know science has limitations," Dr. Miller said. He complained that the theory advanced by intelligent-design advocates had not been submitted to peer review and experimentation the way other theories must be tested to be scientifically accepted.

"They're not a part of science," Dr. Krauss added. "What they're really attacking here is not Darwinism but science."

But Dr. Stephen C. Meyer, a philosophy professor at Whitworth College in Spokane, Wash., and, like Dr. Wells, a senior fellow at the Discovery Institute, argued that "the methods of science are part of the debate" that teachers should air. Science regularly makes "design inferences," he said, such as that the hieroglyphics on the Rosetta stone are evidence of intelligence rather than the random work of wind and erosion.

"It all seems persuasive when you hear only one part of the argument," Dr. Meyer said in proposing that the state compromise by permitting teachers to present both views, without requiring that they do so.

"Let's not persecute teachers," he said.

While Dr. Meyer invoked fairness, Dr. Krauss complained that the school board's format today — hearing two speakers for intelligent design and two speakers against — was "not really fair." Dr. Krauss estimated, given the criticisms of professional organizations, that scientists would break down more like 10,000 to 1 against the idea.

Dr. Meyer cited a recent public opinion poll that he said showed "voters overwhelming favor teaching the controversy," by a majority of 71 percent.

Dr. Krauss replied that science's legacy of endlessly testing evidence meant that "science is not fair," since not all ideas are proved to deserve equal treatment in the classroom. The goal of science, he maintained, is to "learn to accept the universe the way it is, whether we like it or not."