Scientific theory has had a rough time in America’s public schools.

Almost 100 years ago, science teacher John Scopes was convicted of violating a Tennessee law that prohibited teaching the theory of evolution. Although his conviction was overturned on a technicqlity in 1927, laws banning classes on Darwin’s theory stuck around for another 40 years. They were ruled unconstitutional by the U.S. Supreme Court in 1968.

Over the past few decades, conservative or religious groups that object to including the theory of evolution in science classes have tried a different approach. Now, they argue, if the “scientific” theory of evolution is taught, other views, such as “intelligent design” – a stand-in for creationism – should also be taught.

Broadening efforts

The approach is not limited to evolution. Legislatures across the country are proposing or passing laws that purport to encourage scientific discussion, but instead encourage students to treat established, scientific theories as equivalent to ideas that lack scientific study.

In 2012, legislators in Tennessee – the same state where the Scopes trial took place nearly a century ago – approved a law that obligated teachers to present the “scientific strengths and scientific weaknesses of existing scientific theories.” What constituted a scientific “strength” or “weakness” was not defined.

Similar bills were introduced in North Dakota in 2019 and Oklahoma in 2023. If the Oklahoma bill passes, teachers will be encouraged to explore scientific theories in class and to help students “analyze certain scientific strengths and weaknesses.”

And a new law in West Virginia allows teachers to discuss or answer “questions from students about scientific theories.” The bill’s author, state Sen. Amy Grady, said the law is about “encouraging students to think, encouraging students to ask questions and encouraging our teachers to be able to answer them.”

Court battles ahead

In my view, legislation dealing with the teaching of scientific theories is being used to influence what is taught in public schools. The law is likely to face a legal challenge. More than 20 years ago, in Kitzmiller v. Dover, a federal court ruled that intelligent design was not science; it lacked empirical evidence and testable hypotheses. Teaching it would violate the First Amendment’s prohibition against state support of religion.

As an educator – and as a scholar who studies the nature of science – I believe an understanding of scientific knowledge is critical; scientific theories are part of this knowledge.

Accepted scientific theories are the best explanations available so far for how the world works. They have been thoroughly tested and are supported by evidence, often pulled from different fields. For example, evidence supporting large-scale evolution comes from fossils, DNA analysis and comparing the anatomy of different organisms.

Updating theories

Scientific theories can be revised. They can change, or even be discarded, but they are durable. The history of science is full of stories about new evidence, reinterpretation of existing evidence and advances in technology spurring changes in the sciences. For instance, the discovery of the microscope in the 16th century literally changed how scientists saw the world.

Scientific theories have explanatory power about the natural world. The Earth’s gravity, for instance, can be explained through the theory of general relativity. Theories have predictive power, too. They can be used to generate research ideas. As summarized by astrophysicist and author Neil deGrasse Tyson: “A well-constructed theory should explain some of what is not understood and, more importantly, predict previously unknown phenomena that can be tested. A successful theory is one where experiments consistently confirm its predictions.”

Given these characteristics of scientific theories, the current crop of legislation governing how theories are introduced and taught in classrooms is concerning. Underpinning these laws is the assumption that accepted scientific theories are nothing more than conjecture.

Debating facts

For example, a 2023 bill from Montana prohibits science instruction on “subject matter that is not scientific fact.” The bill devalues scientific theories as hunches or unproved assumptions. It undermines their inclusion, as established ideas, in the K-12 curriculum. Atomic theory may be a theory, but it is fundamental to people’s understanding of matter and is a foundation of all the physical sciences.

Legislation that invites classroom exploration, debate or analysis of theories may mask other intentions. The sponsor of Senate Bill 140 in Oklahoma, for example, said he hoped the law would “expose the ‘theory’ aspect of evolution by allowing alternate views to be presented.”

Laws like the one passed in West Virginia go a step further. They open the door to discussions about alternatives to scientific theories. This allows nonscientific notions to be introduced covertly. Writing for the Scientific American, Amanda Townley, executive director of the National Center for Science Education, criticized the West Virginia law. She expressed concern and said such actions can open the public classroom door to false beliefs such as the Earth being flat or that crystals can heal.

Toward scientific literacy

In contrast to legislators who would allow any kind of theory to be taught in science class, experts such as Fouad Abd-El-Khalick, a leading international science education researcher, advocate that students in K-12 be taught about the characteristics of scientific theories in developmentally appropriate ways. U.S. standards for teaching science, for instance, say that by the end of 12th grade, students should understand that a “scientific theory is a substantiated explanation of some aspect of the natural world, based on a body of facts that has been repeatedly confirmed through observation and experiment.”

Students should be encouraged to think critically and ask questions – like “What is the evidence that supports this theory?” or “How was this theory tested?” – with the caveat that any theories in question should have already attained the status of “scientific theory” before being admitted into the curriculum.

Education scholars say K-12 education must provide students a “functional level of scientific literacy” that enables them to understand and make decisions about issues related to science in everyday life, from vaccines to baking cakes.

Part of attaining this literacy is understanding and trusting knowledge produced by science, such as facts, laws – and scientific theories.

Ryan Summers receives funding from National Science Foundation, ND EPSCoR, and the National Institute of Health.