President Trump this week tweeted his intention to order the Department of Justice to investigate whether the FBI had “infiltrated” the Trump campaign for political purposes. He then met with Deputy Attorney General Rod Rosenstein and FBI Director Christopher Wray to push the investigation of special counsel Robert Mueller’s investigation. The episode, like many before it, set off alarms among legal and political commentators. Throughout the 2016 campaign, the outsider candidate demonstrated that he would not be bound by the usual unwritten rules of the game. Political scientists, in particular, have emphasized the decline of “norms” in their efforts to explain the danger posed by the Trump administration and the president’s possible role in the decline of liberal democracy in the U.S.

But as with any word that has picked up heavy traction in political discussions, “norms” has gotten a bit imprecise. What do we actually mean when we talk about norms? Why do such informal rules exist? And what norm violations should we really care about?

Why we need norms

Informal rules tend to emerge around things that we are anxious or doubtful about. Think about social manners. We have norms against cutting in line or eating all the cake at a birthday party precisely because humans don’t seem to be naturally inclined to be generous. We have to be taught to be considerate of other people and socially sanctioned into doing so.

This principle turns out to be especially applicable to presidential politics. Presidential power is vaguely defined in the Constitution, and the office is designed in a way that allows for very broad use of power. Presidents can make decisions about how to conduct foreign policy, fire executive branch officials who don’t do what they want, and make policy by executive order.

Because the executive branch concentrates substantial power and influence in a single person, there are plenty of opportunities for those powers to become political weapons — if they’re left unchecked. In “How Democracies Die,” Steven Levitsky and Daniel Ziblatt describe norms as guarding against just that, as preventing institutions from being used as “political weapons.” We have norms about when and how presidents use their “bully pulpit,” for example, as well as when they should use their power to fire executive branch officials.

Why do we have informal rules (norms) about some things and formal rules (laws and regulations) about other things? One answer that Jennifer Smith and I developed in our research on the topic is that informal rules emerge when there’s some agreement that a rule needs to exist but deep disagreement on the particulars. One example of this is the norm established in the country’s early years that presidents would serve only two terms. There was widespread agreement that there should be limits on how long a single person could hold the presidency. But there were enough objections to any specific time span to make it difficult to put a formal rule in place. Making formal term limits would have forced a difficult conversation about exactly how long presidents should serve and about whether the limits on public accountability were worth it. Adopting an informal rule allowed the country to skip these more difficult conversations and instead just follow George Washington’s lead. (Of course, it took only one violation of this informal rule — FDR’s four terms — to push things over the edge for a more formal change, and that happened only after the country had grown used to the informal two-term convention.)

When we should actually care about norm violations

OK, we really need norms. But we don’t need all norms equally. In the Trump era, norms are invoked with dizzying frequency, and Trump won the White House while violating all sorts of unwritten rules of campaigning. So which norms should we really try to protect?

In short, some norms are more cosmetic and about tradition and convention, and some norms are really about “democratic values.” We care about the latter.

How can we tell which is which? Three categories of norms about presidential behavior tap into crucial aspects of democracy: respecting the independence of other institutions, acknowledging that political conflict is part of the process, and keeping private profit separate from government operations.

Independence of other institutions — American politics depends on the independence of the three formal branches of the national government. So any action that erodes that independence is worth worrying about. Of course, autonomy across branches has been a tricky subject. Presidents obviously try to influence Congress and even sometimes congressional primaries. Members of Congress try to influence presidential elections. You might remember the Supreme Court getting involved in a presidential election. Because interbranch meddling has such a long history, norms may be a less powerful guideline than thinking about whether the president is trying to do something that will weaken the ability of other branches to challenge him.

Political conflict — Let’s see if we can thread this needle. First, the idea of legitimate opposition — that people can oppose and criticize the government without posing a threat to the nation — is a fundamental tenet of democracy. Trump’s violation of that norm has primarily taken the form of tweets about the media and about his Democratic opponents. Journalists and opposition party members have very different roles to play here, and the implications of presidential criticism is different for each. Efforts to delegitimize criticism of the president by the media are alarming (well, I might have a bit of a vested interest here), as are threats to jail opponents. Attacks on congressional Democrats, however nasty, may violate norms of civility but don’t necessarily threaten core democratic values.

After all, it’s the peaceful resolution of political disagreement — not the absence of dissenting views — that’s central to democracy. Corey Robin points out that sometimes norms are actually quite repressive, such as the informal rules and expectations that allowed American slavery to persist in the 19th century until the abolitionists “polarized society.” It’s the criminalizing of political dissent — either by attacking the opposition or denying its standing — that should be worrying.

Public and private — Since Trump won the 2016 election, there have been numerous examples of his family’s private business interests becoming intertwined with government operations. White House counselor Kellyanne Conway drew criticism for advertising Ivanka Trump’s clothing brand during a televised interview. The real estate dealings of the Trump Organization across the globe have made critics nervous. Trump’s hotels and resorts have become part of official state and government business, making it difficult to separate the president’s private business interests from the work of governing. These potential conflicts of interest have thus far attracted many questions and at least one lawsuit. This kind of behavior is constrained through a mix of formal and informal rules. Thus far, it’s proved difficult to rein in, despite widespread agreement that public officials should not profit from their positions.

Thinking more carefully and precisely about norms might actually lead us to more pessimistic conclusions about the risks to U.S. democracy. We depend a great deal on informal rules to constrain the presidency, both because of the powerful nature of the office and because it’s difficult to find agreement about the kinds of formal rules that would limit presidential power. Much of the time when we’re talking about norm violations, we don’t so much mean a departure from standard practice as a breach in democratic principles. The ability to adopt informal rules has sometimes saved Americans from hard conversations about power and the tradeoffs that democracy requires. Those are exactly the kinds of hard conversations we might need to have now.