“Elections have consequences,” said President Barack Obama in 2009, as he started to press for policies such as affordable health care against Republican opposition. Recently Republican leaders themselves have begun to echo his phrase as red state legislatures ban abortion, prevent the country from taking actions to combat the climate crisis, permit easier access to firearms, and oppose a vigorous public health response to the pandemic. All of that makes the consequences of this fall's vote exceptionally profound.

What these issues have in common is overwhelming scientific support for pursuing one policy direction over another. They share something else, too: a choice between candidates who either follow that scientific evidence or act as if it does not exist. On your Election Day ballot you'll see local and federal candidates who endorse policies based on tested scientific evidence and others who take positions based on unsupported assumptions and biases. The scientific method has brought us vaccines, the Internet, cleaner air and water, and entire new sectors of the economy. Office seekers who use research-based evidence to inform decisions are the ones who will help our country prosper. Those who reject this evidence will increase suffering. The following survey of urgent policy issues highlights the differences:

Reproductive and gender rights. When the Supreme Court overturned Roe v. Wade and allowed any state to ban or restrict abortion rights, it let those states force people to undergo the risk of pregnancy against their will. About 50 scientific papers have compared women who received an abortion when they wanted one with women who were turned away. The women denied abortion, followed for several years, had worse physical and mental health. They were also more likely to live below the federal poverty level and be unemployed. Pregnancy itself is far more dangerous than abortion. The U.S. already has a startlingly high rate of maternal mortality, and one study estimates that a national ban would drive up those deaths by 21 percent. Office seekers who support abortion bans ignore such evidence; instead many favor narrow religious doctrine.

Politicians who oppose gender-affirming health care are just as blinkered. Alabama enacted a law criminalizing such care for transgender youth while Texas directed state officials to investigate such care as child abuse. Florida wants the treatments withheld. These positions ignore the lifesaving effects of these treatments. A 2020 study in the journal Pediatrics looked at teenagers who were denied hormone-blocking treatments that temporarily delay puberty while the youth consider their gender. Those teens went on to have a much greater lifetime risk of suicidal thoughts. The effects of this medication are reversible.

Health and the pandemic. This summer Congress passed a budget bill with several key health-care provisions. One was to give Medicare the power to negotiate wildly escalating drug prices with pharmaceutical manufacturers. More than 47 percent of new drugs released in 2020–2021 cost more than $150,000 a year, according to a study in the journal JAMA; only 9 percent of new drugs topped that dollar figure as recently as 2013. The bill will put more lifesaving medications in the hands of more Americans, yet Senate Republicans opposed it. They eliminated a specific provision to cap the cost of insulin at $35 per month for people with private insurance. Right now in the U.S., a single dose can cost more than $300, forcing many of the several million Americans with type 1 diabetes to skip doses. And the evidence is clear that affordable health care saves lives. One study showed that states that expanded eligibility for Medicaid, a low-cost health program, saved thousands of people from premature deaths. States that voted against such expansion went in the opposite direction, and people lost years of life.

The U.S. pandemic response has been filled with missteps on all sides. But many conservative Republican-led jurisdictions have been exceptionally hostile to basic public health measures. Despite the large number of studies showing masks reduce transmission of the SARS-CoV-2 virus (the N95 style is the most effective version), these places resisted mask mandates, even as the U.S. climbed to a nationwide toll of more than one million deaths from COVID. Several Republican-led state legislatures introduced laws that took power away from local public health agencies and gave it to state politicians. And officials in Florida, urged on by Governor Ron DeSantis, refused to recommend COVID vaccines for any children or teens. At that time, 1,200 children nationwide had been killed by the virus, and a study had shown vaccines were 94 percent effective at keeping kids aged 12 through 18 out of the hospital. None of the clinical trials of vaccines in children found serious adverse health events.

Gun safety. In the U.S., we are dying from a plague of gunfire: 45,000 people are killed by firearms every year; the most recent numbers show more children and young adults were killed by guns than by cars. While the pace of mass shootings in 2022—at least one incident a day where at least four people were killed or injured—grabs headlines, most of the thousands of victims are shot one or two at a time. The death toll disproportionately hits people of color. Just more than half of the dead are Black men. And deaths do not capture the entire grim story. Approximately 85,000 people were wounded by gunfire in 2017, the most recent year for which these data are available; many of them have pain and disability for the rest of their lives. Still, many politicians, supported by pro-gun lobby groups, want to relax permit rules and make these weapons of mass destruction easier to get.

One false claim repeatedly made by these officials is that more armed good guys will stop more armed bad guys. Senator Ted Cruz of Texas used this disproven refrain after the school massacre in Uvalde, where in fact many armed good guys (the police) did not stop one bad guy. More to the point, research carried out by investigators at Texas State University using FBI data showed that an armed bystander shot the attacker only 22 times out of 433 active shooter incidents. Even when a “good guy” has a weapon, the carnage is already done. For instance, in a Sutherland Springs, Tex., church shooting, an armed neighbor fired at the assailant but only after 25 people had been killed, including a pregnant woman, and 22 wounded.

When guns are in a home, not out on the street, the research clearly shows that more firearms mean more death and crime. A 2003 study looked at levels of gun ownership among murder and suicide victims. Among gun owners, the odds of becoming a murder victim were 41 percent higher when compared with people who did not keep guns in the house. The odds for dying by suicide were 244 percent higher. That last tragic number is important: of those 45,000 annual firearm-related deaths, nearly 25,000 are suicides.

There are ways to improve gun safety and save innocent lives. These approaches have been studied and demonstrated, and candidates who support them deserve votes. Safe firearm-storage laws should be passed and enforced, for instance. Stricter regulation of gun dealers is an effective measure, as are universal background checks, mandatory licensing requirements, red flag laws, and bans on assault-style weapons and magazines that hold enormous amounts of bullets.

Climate. After being chopped down from trillions to billions of dollars in spending, the Biden administration's climate bill passed, and it does have some significant wins. Chief among them: support for solar panels and wind turbines and funds for clean energy projects in poor communities. But on the state level, some Republican-dominated legislatures are throwing up obstacles to cuts in fossil-fuel use. These reductions, according to scientific consensus, are needed to stop the temperature rise that's driving catastrophic storms, droughts, floods and wildfires in the U.S. Yet West Virginia's attorney general announced plans to sue the federal government if it rules that publicly traded companies have to reveal their levels of greenhouse gas emissions. Several Republican state lawmakers have introduced bills to punish companies if they divest from fossil fuels. And Texas passed a law prohibiting new construction that avoids natural gas as a fuel source.

There are other crucial issues that divide candidates, such as backing state bills that prevent schools from teaching about racism and sexism in American history. Promises to reduce inflation will also get a lot of attention. Take a hard look at these office seekers and their attitudes about policies based on scientific evidence. And then, we urge you, vote for science.

JOIN THE CONVERSATION ONLINE Visit Scientific American on Facebook and Twitter or send a letter to the editor: editors@sciam.com