The beating heart of democracy is free speech. Freedom of religion, freedom of conscience, freedom of thought, these are the point and purpose of democracy. Democracy exists to protect these freedoms and it is justified in its turn by doing so.

But the most important freedom is the freedom to criticize the government. The freedom to speak truth to power is the one and only way to restrain power as it lurches toward authoritarianism.

Democracies do not punish their critics. Ruling parties in democracies do not punish their critics. For nearly 250 years the United States of America, as a beacon of prosperity and a vanguard for progress, has stood as the foremost proof of the wisdom of this principle.

And yet, sadly, as we approach our sesquicentennial year, we are now guided by a president who does not understand why democracies cannot survive if they punish their critics, and cannot be free if its citizens fear retribution for speaking their minds.

Just look at the institutions against which the Trump administration has waged a campaign of retribution:

• Law firms have been coerced into supporting his causes, or risk losing standing in federal courts.

• Scientists have seen their research held hostage until their employers do the administration’s bidding.

• Journalists have been sued into silence. News agencies like the Associated Press have been denied White House credentials

• Universities have seen federal funding for their research and for their students’ aid threatened or revoked unless they police their professors’ language and espouse the administration’s policies.

What do all these institutions have in common? They seek the truth. The moral core of law, science, education and journalism is to seek the truth and speak it. It is because of this that they have become the first targets of our president’s campaign of fear. The goal of sanctioning these institutions is to silence them. Authoritarians fear the truth. Democracies do not.

The American Association of Colleges and Universities recently published a letter repudiating the Trump administration’s attack on freedom of thought and its weaponization of federal funding to manipulate American universities.

The presidents of Colby, Bates, Bowdoin and the University of New England — where I work — signed the letter. So too did leadership at The College of the Atlantic, Thomas College, and the Maine College of Art and Design. They should all be celebrated for having the bravery to do so. Every college in Maine should join them. We have never needed letters like this more. We need them everywhere.

Perkins Coie, a law firm in Seattle, has filed suit against the Trump administration’s weaponization of federal court standing. Five hundred law firms across the United States have filed amicus briefs in support. Maine law firms should do so as well.

We have never needed actions like this more. We need them in every field and on every front possible.

Standing together is how we stand up to authoritarians. Alone we are vulnerable, but together we have strength. Authoritarians can bully individuals, but in solidarity we become too numerous to silence.

Now is the time for statements of principle. Now is the time for public letters. Now is the time to speak out. Find a letter and sign it. Write a letter and ask someone to sign it.

When every American who believes in freedom of speech has signed a letter defending it, every American’s freedom of speech is that much safer.

Democracies do not punish their critics. If we want to keep our democracy, we must hang together; if we do not, as Benjamin Franklin is said to have warned, we will assuredly hang separately.