Last week, several top Democrats were targeted by pipe bombs, two black Americans were killed in what appeared to be a racially-motivated murder, and a terror attack against Jewish Americans in their place of worship that left 11 people dead.

Over the last decade, we’ve witnessed a host of terror attacks and mass shootings — in San Bernardino, in Colorado Springs, in Charleston, in Orlando, in Chattanooga, in Santa Barbara, in Fort Hood, in Santa Monica, in Newtown, in Minneapolis, in Aurora, in Oakland.

The motives in each of these attacks vary, but they’re all united by the common thread of violence.

They also raise difficult questions, like: are American growing more violent? Are we regressing into something akin to what we saw in the 1960s, an era marked by assassinations, civil unrest, and political chaos? Has the cocktail of guns, polarization, and alienation made mass shootings a permanent feature of American life?

To get some answers, I reached out to seven experts to see if they thought that politically motivated violence was on the rise. Their responses were mixed, but most are convinced that we’re experiencing an uptick — and that once this sort of violence takes root, it is hard to stop.

Read their responses, which have been lightly edited for clarity, below.

Joanne Freeman, author of The Field of Blood: Violence in Congress and the Road to Civil War, Yale University

Are we becoming a more violent country? Answered as a simple yes-or-no question, the answer appears to be “yes.” But in truth, the question is more complex.

Last week saw an outburst of violence, all of it tied, in one way or another, to the rising intensity of the political climate as midterm elections near.

In the lead up to those elections, political rhetoric is becoming increasingly heated, as are the emotions of many Americans. And with the rise in violent rhetoric, we’ve seen a tragic rise in violence. As a broad phenomenon, this is nothing new. The United States has a long history of voter intimidation and election day rioting, and some riots have even resulted in deaths.

What’s distinctive about our current moment is that the president of the United States himself is using violent rhetoric. As the nation’s elected leader, his words have added weight, so when he brands certain Americans “the enemy” or suggests that they’re destroying the republic, it matters; it potentially encourages and excites extreme action. To begin to judge the long term effects of this electoral uptick in attack-talk and attacks, we’ll have to watch events after the election, when the heat of the chase begins to dissipate.

Barbara Walter, author of Why Bad Governance Leads to Repeat Civil War, University of California, San Diego

I’ve spent decades researching how and why civil wars start, and people have been asking me whether the US could experience a second civil war. Up until 2016, I would have said no, because the US had none of the risk factors known to lead to civil war. But that has changed.

The two best predictors of whether a country will experience a civil war is whether it is moving toward or away from democracy, and whether its population is polarized. And Americans now live in an increasingly polarized world with a strongman leader intent on subverting democracy.

Until 2016, the US was categorized as a full democracy alongside countries like Switzerland, Canada, and Australia (Polity IV data). Experts now consider it a flawed democracy, in the same category as Chile, Argentina, Uruguay, and South Africa. American citizens may think they still live in a full democracy, but they don’t. They are moving down the democracy scale toward the middle zone.

Americans are also becoming more polarized ... and not surprisingly, violence is increasing. The U.S. was recently placed on the list of “most worsened countries” for political stability by the Fund for Peace, a non-profit dedicated to preventing violent conflict. It has also dropped more than any other country in the world on the Global Peace Index, an index that measures the relative likelihood of peace in countries, declining eleven places to rank 114th out of 163 countries for peacefulness.

Americans aren’t becoming a more violent people, per se. We have always had violence within us and the means to pursue it.

What has changed is the motivation to use violence. As democratic norms and practices have eroded, and people have become more fearful of different segments of society, the incentive to turn to violence has increased. This has been stoked by President Trump.

“In failing to denounce white supremacists unequivocally, Trump has provided a warm spot under his wing where alt-right extremists have found a place to nest”

Christopher Strain, author of Reload: Rethinking Violence in American Life, Florida Atlantic University

We’re in the same place now as we were a year ago after the Las Vegas massacre — which is to say, not in a good place at all. The top-down rhetoric of divisiveness and intolerance continues to have a corrosive effect.

For example, President Trump did his best to turn a minor Fox News segment about a group of migrants fleeing violence in Central America and moving northward into a border crisis for the United States — and he succeeded.

The president claimed that “criminals and unknown Middle Easterners” were in the group, a claim without any basis in fact. Before attacking worshipers at the Tree of Life Synagogue in Pittsburgh, the shooter railed on social media about Jews who had aided and abetted the “caravan” of “invaders.” The murders in Pittsburgh followed a week in which one man mailed bombs to almost a dozen Trump critics and another man deliberately shot two African Americans at a Kroger in Louisville after trying to target a black church.

President Trump continues to vilify the media, and then acts surprised when journalists are attacked. In failing to denounce white supremacists unequivocally, Trump has provided a warm spot under his wing where alt-right extremists have found a place to nest. If he is capable of moderating his rhetoric, swearing off acrimony, and creating unity, then now would be a good time to do it.

Words matter. Political rhetoric matters.

Jacob Shapiro, author of The Terrorist’s Dilemma, Princeton University

With this past week’s tragic events, it makes sense to stop and take stock of what the trends in mass violence have been over the last few years. We hear a great deal that political violence his risen dramatically. But is that really true?

It’s hard to know without a detailed analysis, but one thing we can do easily is look at trends in mass shootings using data from the Gun Violence Archive (GVA), which defines a mass shooting as any event with four or more casualties in one event not including the shooter. This measure combines many kinds of gun violence, but if politically-motivated attacks using guns are rising significantly, that should show up in the data unless there is some countervailing trend in other kinds of gun violence.

So what do we see in the trends? First, there is indeed a long-term rise in the frequency of mass shooting events. That trend largely parallels the overall trends in violent crime (there were 369 incidents per 100,000 in 2013 and 394 per 100,000 in 2017 according to FBI statistics), making it hard to know if there something specifically political about the trend.

One simple way to try to get at the source of the increase is to analyze trends separately in states President Trump won in 2016 vs. those in which he lost. As you can see in the figure below, doing so shows that the upward trend in the rate of mass shootings since 2013 is larger in states that President Trump carried. However, there is no discernible increase in the rate of mass shootings since President Trump took office in Nov. 2016.

Seeing exactly what is going on is challenging because there are more mass shootings in the summer, but two observations stand out. First, these is a large increase in Summer ’15 compared to Summer ’14 in states where the president won. Second, Summer and Fall ‘16 saw more frequent mass shootings than earlier periods in both kinds of states. Whatever is driving the trend over time, it does not appear to have gotten worse since the 2016 election.

Since summer 2013 the frequency of mass shootings has gone up more in places which supported President Trump in 2016 than in places which did not. One can interpret that many ways. What is clear is that the aggregate data are consistent with the claim that politically-motivated violence is on the rise.

Christian Davenport, author of The Peace Continuum, University of Michigan

Given history as baseline, I would say that the United States is not becoming a more violent people, a more violent country. The United States was much worse in its past and one of the reasons why violence is so low in frequency, intensity and scope now is because of how much bloodshed has been spilt to get to this point.

We need to remember that violence has generally been a small (albeit noteworthy and newsworthy) fragment of human interaction.

Most of our lives are spent in various degrees of peaceful harmony or, as discussed in my recent book, some place along a peace continuum. That said, it’s important to consistently question the violent nature of a country that spends more than half of its tax dollars on the military and national security.

If the identity of the US is so intricately connected with militarism, weapons, imprisonment (without the objective of reform), harsh sentencing, aggressive/intimidating policing, the death penalty and interventionism (at home as well as abroad), then the existence of violent episodes like the most recent tragedy in Pittsburgh fits a broader pattern — perhaps not in frequency, severity or scope but in intent and form.

“People have been asking me whether the US could experience a second civil war. Up until 2016, I would have said no.”

Steven Johnston, author of American Dionysia: Violence, Tragedy, and Democratic Politics, University of Utah

America was decidedly violent long before Cesar Sayoc (the recent mail bomber) and Robert Bowers (the man who attacked the Tree of Life synagogue in Pittsburgh) burst into public view. Nevertheless, we might take this moment to reflect on the condition of American politics and the violence that too often characterizes it. Even before Trump, the Republican Party deemed itself the sole legitimate force in American political life. As such it is unwilling to compromise with adversaries.

Think here, for example, of its determination to destroy Barack Obama’s presidency from day one, or its perverse insistence on confirming Brett Kavanaugh, a dime a dozen right-wing jurist. The Republican Party is also willing to do anything to keep itself in power regardless of its effect on democracy. And why not? It does not believe in democracy. Think of its nationwide efforts to suppress voter turnout, especially but not exclusively along racial lines.

In short, the GOP has made it clear, in word and deed, that it has no intention of sharing a polity with others.

We should be even more concerned about the effect that Trump’s ascendancy (and the Republican Party’s fealty to him) is having on the United States. Public discourse has become particularly venomous, and it’s an open question as to how that discourse might encourage or embolden certain people to act. On any number of occasions Trump has expressed his approval — explicitly and implicitly — of violence against a wide range of political opponents, which he considers enemies.

When Trump and the GOP communicate to their constituencies that they are under attack by foreigners or by foreign elements in America, and that their very way of life is in danger and needs to be protected, this kind of narrative and rhetoric can have pernicious effects. When they’re matched by grandiose actions (like Trump sending thousands of troops to the southern border to protect the nation from desperate refugees), many of those who nurture a deep sense of rage and resentment about a “lost” country, and many of those who consider themselves true patriots are only too happy to take matters into their own hands and deliver a decisive blow for what they hold sacred.

So it shouldn’t surprise anyone when white nationalists take up the calls to arms that Trump and his Republican lieutenants have issued. The latter will disavow the likes of Sayoc and Bowers, of course, but continue to feed the passions that helped manufacture these culture warriors.

Joseph Young, professor of justice, law and criminology, American University

In the longer term (1800s to today), we are definitely a less violent place. This isn’t the 1850s, the civil war era, the 1960s, or any other exceptionally violent period. There is, however, an uptick in political violence. I hesitate to lay this all at the feet of our current president, though.

Like Brazil, Hungary, Russia, and others, we elected a right-wing populist with little concern for democratic norms and processes. There are enough people on the left and right that feel they are not gaining from participation in institutional politics. That is a worrisome and a violence-enhancing trend. Most of the intense political violence we currently see is from people like Dylan Roof ( the Charleston church shooter) or Robert Bowers ( the Pittsburgh synagogue shooter) or James Hodgkinson (Republican baseball team shooter).

The terrifying thing about what we’re seeing now is that anyone could be an attacker, and these attacks seem to develop through online interactions that escalate, and it is extremely difficult to stop. The upside of individual politically-motivated violence compared to organized group violence is that it is less sustained and less of an existential threat to the state. That is no consolation to the families of the victims.