When in cold reflection, a man concludes that his life matters to no one but himself, how are we to imagine he might still retain or develop an appreciation for the value of the lives of others?

It’s easy enough to characterize Robert Bowers’ deadly attack at a Pittsburgh synagogue as a product of hate-filled political discourse fueled by the inflammatory words of a cynically divisive president and yet that doesn’t account for the abject sadness of a man who had long lived in “his own little world.” Before fuming rage comes the starvation of hope.

Even as a teenager, Bowers was described by a former friend as “pretty much a ghost.” The New York Times reports, “His next-door neighbors also described him as a man who was barely there.” Before murderously announcing his presence to the world, Bowers seemed in many respects to be living an invisible life.

If we now identify mass killing, hatred, and anti-Semitism as the problem, then we are going to focus on circumstantial causes such as the rise of white nationalism, hatred amplified through social media, combined with readily available firearms. But this ugliness festers in a wider context: the largely invisible lives endured by millions of Americans whose social bonds are weak, tenuous, or non-existent.

In a culture that celebrates the fiction of “self-made” success, we are encouraged to believe that even in isolation we somehow have the capacity to define our self-worth, but humans are not a solitary species. As much as we cherish our autonomy, we need other people in our lives.

As the Catholic philosopher, Jean Vanier, has written:

To be lonely is to feel unwanted and unloved, and therefore unlovable. Loneliness is a taste of death.

It’s easy to see xenophobia and hostility to immigrants as simply products of racism, and to varying degrees no doubt they are, but beneath this bigotry runs a deeper current: the experience of individuals who feel neglected while believing the very thing they silently hunger for — inclusion — is being offered to others.

Trumpism offers a fake ointment for this injury by constructing an illusion of inclusion — a society that puts Americans first — but in actuality simply expands and inflames social divisions.

After Elliot Rodgers killed himself and six people near the UC Santa Barbara campus in May, 2014, Niobe Way wrote:

Our culture prizes independence over human connection. It devalues and even discourages close friendships, particularly among boys and men. And our definitions of manhood emphasize aggression, toughness and rugged individualism at the expense of girls, women and relationships.

We know these aspects of our culture lie at the root of the problem not only because killers, like Rodgers, tell us so in their journals and media postings. The science has also been telling us so for decades. We simply aren’t paying attention.

Neuroscientists, developmental psychologists, evolutionary anthropologists, primatologists and health researchers agree: Humans need and want close relationships, including friendships, and when they don’t have them, there are serious physical and mental health consequences.

Last year, Politico reported that across America, social isolation is increasingly viewed as a public health crisis:

Someone who lacks social relationships has the same risk for early death as someone who is severely obese, according to a 2015 analysis by researchers at Brigham Young University. The feeling of loneliness, or a person’s perception of being isolated, has been linked to higher blood pressure and cognitive decline.

A 2018 Cigna study finds loneliness at epidemic levels:

• Nearly half of Americans report sometimes or always feeling alone (46 percent) or left out (47 percent).
• One in four Americans (27 percent) rarely or never feel as though there are people who really understand them.
• Two in five Americans sometimes or always feel that their relationships are not meaningful (43 percent) and that they are isolated from others (43 percent).
• One in five people report they rarely or never feel close to people (20 percent) or feel like there are people they can talk to (18 percent).

A society marked by so much loneliness has lost much of the fabric that’s required to hold any society together. Indeed, a nation made of so many individuals increasingly experiencing the pain of isolation more than being nurtured by their connections with others is already in the process of social dissolution.

While violence and political divisions capture the headlines, America’s social breakdown long preceded the emergence of Donald Trump and the creation of social media — an incremental and quiet breakdown that is all the more destructive because it captures so little attention.

Unless we come together, we inevitably fall apart.