Rosabeth Moss Kanter holds the Arbuckle professorship at Harvard Business School She co-founded and directed the Harvard University Advanced Leadership Initiative. Her latest book, Think Outside the Building: How Advanced Leaders Can Change the World One Smart Innovation at a Time, will be published in January. The opinions expressed in this commentary are her own.

Corporate courage is in short supply. CEOs generally avoid controversial public issues lest disgruntled groups strike back. That's why Walmart's actions to limit ammunition sales and advocate for new gun safety legislation mark a significant milestone. CEO Doug McMillon's leadership heralds a new era of CEO courage in which the private sector takes responsibility for issues that elected officials are ducking.

Exercising courage isn't taking random action in response to a momentary crisis. Effectiveness requires a clear mission and strategy. Courage involves sacrifice for a greater good (e.g. being willing to take a short-term sales hit from the absence of a profitable item) in an effort to support social responsibility over the long term. CVS Health CEO Larry Merlo led the company to remove tobacco sales from its retail stores and offer smoking cessation products and services as part of a long-term transformation into a health care company.

For Walmart, no one knows how phasing out ammunition will affect its bottom line. Walmart is playing a longer game, apparently betting on more growth online and in suburban and urban areas. Loss of short-term sales could be offset by additional attention from Millennials, who say that they want their purchases to reflect their values, including sustainability and safe communities. McMillon's actions bring Walmart into greater alignment with this population. And employees, too, increasingly want to work at a place that reflects their values, pays them a fair wage and is safe.

Leaders can't undertake significant change impulsively, addressing contentious issues with guns blazing (so to speak). Even when courageously addressing a big issue, they must keep the temperature down and the situation contained. Walmart's tone from the top has been respectful. McMillon stressed that he is a gun owner, implying that he understands the needs of gun rights advocates. He implied that Walmart is not "anti" anything; the company is "for" safety and preventing misunderstandings that produce tragedies. No ideology — just pragmatism about safety. Something that is legal and loved can still require caution: It's like parents who love football signing up their kids for soccer instead to reduce risk of concussions.

Courage is not foolhardiness; it is a matter of deliberation and judgment. Courageous leaders want to see all the nuances in a situation so that they can keep risks in perspective before taking them. Walmart wisely took a month after the mass shooting in its El Paso store before announcing changes. Companies must know the limits of what they can do without jeopardizing other activities and people. It's often one small but well-chosen step at a time.

Read More