The writer is a political theorist at Harvard University and a contributing columnist for The Post.

Donald Trump has set a big, fat trap for Hillary Clinton, and so far she has stepped right into it. He turned his attacks against women against her. She is, he argued, playing the “woman card.” And Clinton anted up, offering her supporters the chance to buy a “woman card.” From now until Nov. 8, Trump will surely continue to insult women. If Clinton routinely responds to those attacks, Trump will turn her into the “women’s candidate,” and she will lose. She is already perilously close to being that candidate.

Let’s be honest. Polling shows that Trump has a problem with women, but it also shows that Clinton has a problem with men. Thanks to Bernie Sanders’s pushing and prodding over the course of the primary, Clinton’s vision has expanded, but we all know its core: She is a battle-tested warrior for women and children.

Consider her slogan, “Fighting for us.” For many men, this slogan would have to be experienced as emasculating. A woman fighting for them? Rightly or wrongly, the slogan rubs the wrong way in relation to traditional notions of masculinity. Her slogan itself reveals a limited conception of who she seeks to represent. This is a potentially fatal flaw in Clinton’s campaign. The more that Clinton takes Trump’s bait around the issue of his denigration of women, the more powerfully this flaw in her own campaign will show itself.

Republican presidential candidate Donald Trump slammed Democratic front-runner Hillary Clinton, saying that "the only card she has is the woman's card." (Reuters)

Clinton needs to fix this problem, and fast. And she needs to avoid taking Trump’s bait.

There are important lessons to be learned from the many Republican candidates who rose to the bait and were decimated by Trump’s rhetoric. His monikers for them consistently had two effects: They pushed his foes off message and also forced them to fight on turf that Trump chose for them. Trump wants to rumble with Clinton in a battle of the sexes because he believes that it will be losing terrain for her. He is right that this ground favors him. After all, this is the terrain on which the #NeverTrump campaigners largely fought him, and they have failed.

How then ought Clinton to respond?

First, she should let her surrogates do the work of responding to issues raised by Trump that would pull her off her core message. She should let her surrogates do the work of replacing his labels with her own. Personally, she should meet his insults with a cheery silence, or a lighthearted deflectionary joke. She needs to become Teflon — not to engage.

Second, each week, Clinton needs a message powerful enough to rival the rhetorical force of Trump’s own messages. How many of us can say what Ted Cruz’s or John Kasich’s messages have been in the past eight weeks? But we can all say what Trump’s have been. “The Republican primary process is rigged.” “The person who gets the most votes should get the nomination,” and so on. Clinton needs weekly messages that meet the moment and drive the conversation.

Third, and most important, Clinton needs to force Trump to fight on the ground he has claimed as his own. No one has yet forced him to do that. She needs to challenge him on the terrain he is seeking to defend. Rather than simply fighting for women and children, Clinton needs to fight Trump for the votes of men. His slogan is, “Make America Great Again.” Hers should be, “Make America Fair Again.”

Can we be great without being fair? No we cannot.

Do women want fairness? Yes. Do men want fairness? Yes. Do African American, Latino and Muslim Americans want fairness? Yes. Do white Americans want fairness? Yes. Do religious Americans want fairness? Yes. Do gay, lesbian and transgender Americans want fairness? Yes.

Is Trump ready to be fair? No. He’s a dirty fighter. That tells us all we need to know.

So my advice to Clinton is to take the fight to Trump. Pledge to make America fair again. After all, America the fair is America the beautiful, and America the beautiful is pretty great. Just remember how the song goes. Here’s the fifth verse :

O beautiful for halcyon skies,

For amber waves of grain,

For purple mountain majesties

Above the enameled plain!

America! America!

God shed his grace on thee

Till souls wax fair as earth and air

And music-hearted sea!

What’s more, America the fair, America the beautiful, is plainly against Donald Trump, the narcissist who lacks self-control and disrespects basic constitutional rights. Here’s a little bit more:

America! America!

God mend thine every flaw,

Confirm thy soul in self-control

Thy liberty in law!