HARRISBURG -- The national debate over "intelligent design" and whether it ought to be taught in public schools played out in the Capitol yesterday during a hearing on a House bill that would allow schools to introduce to their students the competing theory to evolutionary Darwinism.

Intelligent design's supporters say life is so complex that it likely is the result of deliberate design by some unidentified creator, not random evolutionary mutation and adaptation.

The proposed law says that during "any public school instruction concerning the theory commonly known as evolution, a school board may include, as a portion of such instruction, the theory of intelligent design."

The informational hearing, conducted by the House subcommittee on basic education, pitted supporters of the intelligent design concept against opponents who think it is at best faulty science and, at worst, Judeo-Christian creationism dressed up in new scientific terminology.

Nationally, the debate is playing out in many state capitols and school administration buildings. In Pennsylvania, the debate formally began when York County's Dover Area School District voted to require teachers to talk about intelligent design in a ninth-grade biology course. The Dover school district was subsequently sued.

Yesterday's hearing, purportedly about whether the design concept ought to be taught in schools, was mostly a back-and-forth discussion on the merits and drawbacks of intelligent design.

The battle lines were drawn in the hearing's opening minutes, when Lancaster's Rep. Tom Creighton, the prime sponsor of the bill, urged everybody to reveal their biases, then furnished some of his own, suggesting people who subscribe to evolution were generally atheists, while the intelligent design crowd are biblical creationists.

The foils themselves, meanwhile, go to great lengths to demonstrate the exact opposite. Many scientists who support evolution note that they are faithful churchgoers. And those scholars who say that nature presents evidence of an intelligent designer simultaneously say that the designer is not necessarily a benevolent deity.

Intelligent design "tells you that Mount Rushmore and the pyramids are designed," said Franklin & Marshall College philosophy professor Michael Murray, in suggesting that the very complexity of life implies that something smart created it, just as we'd infer the same thing about a car, a stopwatch or Mount Rushmore. But intelligent design "can't tell you whether God, man or the Martians did it."

Yet the identity of this intelligent creator is the elephant in the room, and opponents of the design concept say that, unless the Martians did it, intelligent design by default points to a supernatural creator. And that points to a belief that is fundamentally rooted in religion, not science.

Intelligent design is all about "political, rather than scientific goals," of its proponents, said Janice Rael, president of the Philadelphia-area chapter of Americans United for the Separation of Church.

She cited writings from Phillip E. Johnson, author of "Defeating Darwinism by Opening Minds," in which he lays out a "wedge strategy" of undermining evolutionary theory by "phrasing the argument in such a way as you can get it heard in the secular academy, and in a way that tends to unify the religious dissenters."

Even though some scientists -- most prominently Lehigh University biologist Michael Behe, who testified yesterday -- give the intelligent design concept the appearance of scientific endorsement, or at least credibility, those scientists represent a very vocal minority, said Randy Bennett, a biology professor at Juniata College.

"[Intelligent design] offers nothing but untestable assertions, not scientific hypotheses," Bennett said. He called it an updated version of "natural theology," wherein researchers begin with the assumption of an intelligent creator, then assemble evidence to support that assumption. He also disputed the contention among intelligent design proponents that evolutionary theory hasn't been updated since the days of Darwin -- research on evolution is ongoing today, he said.

Behe said cells, the building blocks of life, are themselves "complex, functional mechanical systems," and that the inference that these systems were designed by a creator "is not a religious conclusion. It is a conclusion based on physical evidence."

Both Behe and Murray said that evolution and intelligent design aren't necessarily opponents. They can be taught side by side -- for example, it's possible, Murray said, that the intelligent designer built life's mechanisms, set them in motion like a giant clock, then let life evolve over millions of years according to Earth's natural laws.

Creighton's bill would not force all school districts to teach intelligent design, but rather would provide legal cover for the districts that wanted to do so. A change in the public school code would mean the state says it's OK to teach intelligent design.

If the law is passed, it would almost certainly be tested in court. A challenge to Louisiana's law forbidding the teaching of evolutionary theory in public schools unless accompanied by a separate lesson in "creation science" was litigated all the way to the U.S. Supreme Court. The Supreme Court, in 1987, rejected that law, saying it violated the First Amendment because it "impermissibly endorses religion by advancing the religious belief that a supernatural being created humankind."

Gov. Ed Rendell's office had no comment on the bill, except to say that his staff is examining the bill's constitutionality.