When U.S. Vice President Mike Pence recently confessed that he would never have a meal alone with a woman who was not his wife, he was invoking the well-worn Billy Graham Rule, named after the protestant evangelical leader who famously avoided not only meals, but also car and even elevator rides alone with a woman. The reason? To avoid tarnishing his reputation by either falling prey to sexual temptation or inviting gossip about impropriety. But at the heart of it, such “quarantines” serve to perpetuate the notions that women are toxic temptresses and are a form of benevolent sexism. As a result, women don’t get the mentoring and opportunities they need to thrive, and organizations miss out on their talent.

Leer en español Vincent Tsui for HBR

When U.S. Vice President Mike Pence said that he would never have a meal alone with a woman who was not his wife, he was invoking the well-worn “Billy Graham rule”; the evangelical leader has famously urged male leaders to “avoid any situation that would have even the appearance of compromise or suspicion.” Translation: Men should avoid spending time alone with women to whom they are not married. Graham has been known to avoid not only meals but also car and even elevator rides alone with a woman. The reason? To avoid tarnishing his reputation by either falling prey to sexual temptation or inviting gossip about impropriety.

Think Pence’s quarantine of women is unique? Consider a recent survey by National Journal in which multiple women employed as congressional staffers reported (and male colleagues confirmed) the existence of an implicit policy that only male staffers could spend time one-on-one or at after-hours events with their (male) congressmen. Cut out of key conversations, networking opportunities, professional exposure, and face time with career influencers, female staffers naturally are underrepresented in leadership positions and — not surprisingly — earn about $6,000 less annually than their male peers.

The Billy Graham — and now Mike Pence — rule is wrong on nearly every level. Lauded by some as an act of male chivalry, it is merely a 20th-century American iteration of sex segregation. When women are, in effect, quarantined, banned from solitary meetings with male leaders, including prospective sponsors and career champions, their options for advancement, let alone professional flourishing, shrink. The more that men quarantine women, excluding them from key meetings, after-hours networking events, and one-on-one coaching and mentoring, the more that men alone will be the ones securing C-suite jobs. The preservation of men and the exclusion of women from leadership roles will be perpetuated everywhere that the Billy Graham rule is practiced. Score another one for the old boys’ club.

Whether codified or informal, sex quarantines are rooted in fear. At the heart of it, policies curbing contact between men and women at work serve to perpetuate the notions that women are toxic temptresses, who want to either seduce powerful men or falsely accuse them of sexual harassment. This framing allows men to justify their anxiety about feeling attracted to women at work, and, sometimes, their own sexual boundary violations. It also undermines the perceived validity of claims by women who have been harassed or assaulted. Although thoughtful professional boundaries create the bedrock for trust, collegiality, and the kind of nonsexual intimacy that undergirds the best mentoring relationships, fear-based boundaries are different. By reducing or even eliminating cross-sex social contact, sex segregation prevents the very exposure that reduces anxiety and builds trust.

To build closer, anxiety-free working relationships with members of the opposite sex, thoughtful men will be well-served by having more, not less, interaction with women at work. In a classic series of studies, psychologist Robert Zajonc discovered that repeated exposure to a stimulus (such as a gender group) that previously elicited discomfort and anxiety helped reduce anxiety, and actually increased the probability of fondness and positive interaction. Termed the mere exposure effect in social psychology, the principle has been particularly useful in changing negative attitudes about previously stigmatized groups. Excellent leaders initiate positive developmental and collegial interactions with as many types of people as they can — deliberately, frequently, and transparently.

Perhaps the most disingenuous and deceptive quality of the Billy Graham rule and other forms of sex segregation at work may be their superficially honorable and chivalrous nature. This “benevolent sexism” includes evaluations of women that appear subjectively positive but are quite damaging to gender equity. In their pioneering research on the topic, psychologists Peter Glick and Susan Fiske discovered that women often endorse many benevolent forms of sexism (e.g., that women are delicate and require protection, or that sex quarantines at work help preserve women’s reputations), despite the fact that the sexism inhibits real gender equality. This may explain why many women applauded Pence’s stance as evidence of his character and commitment to his marriage. But sexism always diminishes and disadvantages women at work; even benevolent sexist policies, which lack transparent hostility and appear “nice” on the surface, lead to lower rates of pay and promotion, regardless of how many women support them.

Here is something most men fail to consider when invoking sex quarantines at work: What does their unwillingness to be seen alone with a woman say about them and males more generally? When a man refuses to be alone with a female colleague on a car trip or in a restaurant, owing to fear of something untoward happening, we must ask: Dude, do you, or do you not, have a functioning frontal lobe? Sex quarantines reinforce notions that men are barely evolved sex maniacs, scarcely capable of muting, let alone controlling, their evolved neurological radar for fertile mates of the opposite sex. Sex quarantines paint men as impulsive, sexually preoccupied, and unable to refrain from consummating romantic interest or sexual feelings if they occur in cross-sex relationships. The “sex-crazed” male stereotype is often reinforced in the process of male socialization, and there are plenty of men who, at least on some level, fear breaking rank and violating these expectations of male behavior. This is where moral courage comes in. The fact is, many men choose not to fulfill this stereotype; many men have close, mutual, collegial relationships with women and never once violate a relational boundary.

Of course, the Billy Graham rule and other efforts at quarantining women suffer from a number of logical inconsistencies. For instance, there is the efficacy problem: Rigid efforts to eliminate cross-sex interaction in the workplace have not proven effective. Even in the most conservative religious denominations, nearly one-third of pastors have crossed sexual boundaries with parishioners. Then there is the uncomfortable truth that the Billy Graham rule denies the reality of LGBT people and that sexual and romantic feelings are not limited to cross-sex relationships. The logic of sex quarantine thinking would dictate that a bisexual leader could never meet alone with anyone! Finally, the truth is that sex-excluding policies are rooted in deeply erroneous dichotomous thinking: Either I engage with women at work and risk egregious, career-threatening boundary violations or I avoid all unchaperoned interaction with women.

So what’s an evolved male leader to do? In the simplest terms, become what we call a thoughtful caveman. Healthy, mature, self-aware men understand and accept their distinctly male neural architecture. If they happen to be heterosexual, this means they own the real potential for cross-sex attraction without catastrophizing this possibility or acting out feelings of attraction, to the detriment of female colleagues. Thoughtful cavemen employ their frontal cortex to ensure prudence and wise judgment in relationships with women and men.

Here is a final reason why even devoutly Christian men like Mike Pence and Billy Graham should be dubious about isolating and excluding women at work: Jesus himself was known to meet alone with women (e.g., the Samaritan woman at the well). It seems that showing kind hospitality and elevating the dignity of women was more important than any threat of gossip.