Bebeto Matthews, Associated Press
A New York Police Department officer stands next to a body covered under a white sheet near a mangled bike along a bike path Tuesday Oct. 31, 2017, in New York. Police responded to a report of gunfire a few blocks from the World Trade Center site and memorial, and witnesses say a vehicle drove down a popular bike path and struck pedestrians and cyclists.

Within a single week, two unrelated acts of terror were committed on U.S. citizens by U.S. citizens. Eight people were killed as they rode their bicycles in downtown New York on Halloween. The other act of terrorism cost the lives of 26 people less than a week later as they attended church in Texas. In both cases, a “lone wolf” took it upon himself to send a perverted message. And, in both cases, the result was a mass tragedy where not even the young were spared.

Terrorism has been and remains a problem. However, when most Americans hear the word terrorism, they think of a religion. For most, it's radical Islam. But the drive-by shootings of our inner cities are not inspired by Islam. Oklahoma City bomber Timothy McVeigh was not inspired by Islam. The most deadly mass shooting in U.S. history, which occurred in Las Vegas, was not inspired by Islam. Each of these persons used terror and did terrible things, but none was motivated by what most Americans think of as the source of terrorism. Perhaps we aren’t considering the true source?

Tribalism is an “us versus them” mentality: liberals versus conservatives, red state versus blue state, religious versus secular, educated versus non-educated, etc. Us-versus-them thinking sets up a rigid way of perceiving the world: If you’re not part of my tribe or group, then I cannot give you an inch because I’m too afraid that you’ll take a mile.

Certainly, differences exist in pluralistic societies, like America, and we have to acknowledge such differences: being black (or white) matters; being rich (or poor) matters; being religious (or not) matters, etc. But do our differences have to define us in ways that pull us back into the defensive echo chambers of our own perceptions? Where exactly has this gotten us before?

In a speech that was largely overshadowed by terror, Sen. John McCain recently stated, "We have to fight. We have to fight against propaganda and crackpot conspiracy theories. We have to fight isolationism, protectionism and nativism. We have to defeat those who would worsen our divisions."

Tribalism, or what McCain called isolationism, would have us fight each other rather than form connections of understanding, which can defang lone wolves before they begin to howl. I know of no terrorist — foreign or domestic — who was not an avid believer in the tribalism that McCain bravely spoke against. Such persons may have considered themselves a tribe of one, but they all staunchly believed in a “me-or-mine-against-the-world” mentality.

Perhaps tribalism — whether it’s found in a gang, in a clan, in a clique or on cable news — is the real enemy. Specifically, tribalism ferments the thought process that makes terror possible.

As if all that weren’t bad enough, tribalism is also counterproductive because it inspires inefficiency. I believe tribalism poses one of the largest, unspoken regulations that a society can impose upon itself. It acts like an undisclosed tax against innovation. As the free exchange of ideas constricts, so does the free market. A culture that divides the free exchange of ideas through defensive us-versus-them thinking produces inferior products and few — if any — long-term solutions to complex problems. (See U.S. Congress.)

Our greatness as a nation has always been a reflection of united pluralism — not rigid division. The antidote to tribalism is to cease “doubling down” lest we lose face. It is to cease bumper-stickerifying complex ideas. It is to cease making our point our only priority. Civil, respectful dialog based on mutual discretion is not a weakness; it is one of the greatest strength that we, as a pluralistic society, can have. Terrorism is a symptom, not a cause. And stopping the cause or true source of terrorism — not turning on each other — should be the priority.

In all its extremity, tribalism eventually becomes a malignant cancer. There is much we can do to reach out to those who are not part of our tribe or identity. Maybe we won’t gain fame or sound bites for doing so, but we may decrease the disconnection that feeds tribalism, which — in turn — creates and sustains terror. Will we find the strength to do this? If not, we all but guarantee that terror wins and lone wolves multiply. The better angels of our natures demand more of us.

Bryan Bushman, Ph.D., is a licensed clinical psychologist in Ogden, Utah.