Apparently I have phase shifted into the kind of officially and unofficially senior person to whom one earnestly asks listicle questions about professional topics. A few days ago I was asked about leadership. I was wearing my “Distinguished Engineer” hat, I was in front of the business unit, and I had been framed as someone with outsized tenure and impact. My response garnered massive engagement in the backchannel chat — truly shocking amounts of engagement — so apparently it was valuable, and here I write it for posterity.

I situate “leadership” in a general observation about people. If you’re out socializing with a group of friends and you need to get them to physically move, you can’t just walk away and expect your walking away to spark a change in the wider group. Groups have inertia. A single person doing their own thing probably won’t even be noticed. To cause a change, you need to get two people to walk away: one to lead, and one to follow. Once the second person follows, the rest of the group will follow as well. The second person is the key. The second person has the power.

We see this exact same pattern in work meetings. Someone has an idea or suggests some flight of fancy. For that idea to be adopted, someone else also needs to express support for the idea. The intellectual dynamic echoes the physical dynamic: most people are happy to just stick with the group and do their highly local thing. But once there are two people moving the same new direction, the rest of the group follows. The second voice is the key. The second person has the power.

The observation that “it takes two to move a group” has two implications for management. First, management wields power by simply being willing to be a second voice. By calling out the good ideas, the boss guides the team toward the best outcomes available. Much of management work is leadership.

But anyone can be the second voice, calling out good ideas when they see them. In fact, I’m convinced organizations work best when they make decisions as low in the hierarchy as is reasonable. Decision making engenders ownership, it aligns incentives, and it allows the people with the most knowledge to make the right call. Ceding leadership to management is common, but the most effective teams often have multiple people who alternate acting as the second voice for each other’s good ideas.

Needing two voices to move a group has a second implication for management. If the manager can’t trust the team to generate some good ideas, the manager is totally stuck. You can’t lead a group when no good ideas get proposed, because your voice has nothing to get behind. You can’t lead a group by suggesting your own ideas, because the team might not garner that crucial second person’s support on an acceptable idea. And heaven forbid your team has a you-scratch-my-back-I’ll-scratch-yours voting ring whose incentives are orthogonal to those of the wider organization; you’ll never break them free with the ring intact. To be a successful managerial leader, you must have folks on the team whose ideas and judgment you trust. Ensuring you have reliable leaders in the room is key to your success in your role.

So, my take on leadership: Leaders verbalize their belief in the good ideas they encounter. They trust their own judgment. They are willing to put their necks out and be the second mover. Leaders are the people who regularly and successfully are the second voice.

The importance of the “second mover” came to me by way of common knowledge for line management and field trips in K-12 education. (I love the education literature. The whole field of classroom management is dedicated to exceedingly practical advice on getting a group of people with varying levels of interest and motivation to behave in the ways you need, while avoiding resentment and maintaining everyone’s dignity.) Reiterating ideas is also key to the “amplification” technique (archived) that women used in the Obama White House in 2016 to make sure their contributions were recognized.