Textbooks emerged Monday as the new battle front in the evolution debate.

In a 3-to-2 vote, a House education subcommittee authorized the addition of language to a Senate bill that directs the state Board of Education to approve only textbooks that “emphasize critical thinking and analysis in each academic content.”

The amended bill is Rep. Bob Walker’s latest effort to break a stalemate that has stalled the approval of a single page of revisions to biology standards that guide high school teachers on how to address the subject of evolution and diversity of life.

Most science educators reject attempts to inject the phrase “critical thinking” into lessons about evolution because they insist it invites religious discussions — specifically about creation — that are difficult to prove.

“This has nothing to do with intelligent design or creationism,” Walker said. “It’s a way to help young people to look at things more realistically.”

Pierce McNair, the state Department of Education’s chief lobbyist, said Walker’s proposal “may be confusing to some teachers and districts.”

“Is he saying there should be critical analysis of all subjects?” McNair asked. “How can you critically analyze German, or algebra, or keyboarding, for that matter? The language of the bill may not fit the reality of the subject being taught.”

All textbooks the state’s 1,100 schools use should emphasize lessons that challenge students and teachers to look at topics from several viewpoints, Walker said.

“We think it ought to be across-the-board,” the Spartanburg Republican said.

The amended Senate bill goes to the full House education committee, where scrutiny is likely.

If approved by the House, members of both chambers would meet to reconcile the versions before sending the reconciled bill to the governor.

Rep. Ken Clark, R-Lexington, joined Rep. Mike Anthony, D-Union, in voting against the amended language Monday.

Clark opposed it because he wanted more time to think through its broader implications.

“‘Critically analyze’ — what does that mean?” Clark asked. “By changing the (current textbook) law, are we trying to address a short-term issue with a long-term solution?

“What are the motivations behind it?” Clark asked. “I think it’s pretty obvious, given all the talk about intelligent design.”

Over the past several months, Walker and state Sen. Mike Fair, R-Greenville, have emerged as vocal advocates of modifying the science guidelines for discussions about evolution in high school biology classes.

Both lawmakers insist they are not trying to sneak religious instruction into science classrooms and laboratories. They say enough evidence exists that contradicts or questions Charles Darwin’s theory of evolution that students should be exposed to other competing theories.

The state Board of Education rejected efforts by Walker and Fair last month to modify the biology science standard for teaching evolution that would have given teachers more leeway in lecturing about alternatives to the theory of natural selection.

Under state law, the Department of Education conducts cyclical reviews of teaching standards that guide educators in how to present lessons subject to standardized testing. The state Board of Education is responsible for endorsing any changes or revisions, which it has done at least three times in the case of the biology standards.

A separate state agency — the Education Oversight Committee — has the authority to approve or reject standards and has clashed with the state school board over the evolution standard.

Walker said Monday he is lobbying state school board members to reconsider.

Reach Robinson at (803) 771-8482.