When confronted with the revelations that the National Security Agency has been gathering intelligence on millions of American citizens, President Barack Obama responded, “Let’s have that debate.”

Let’s. But let’s have a debate with rules, reason and a real outcome.

The debate defense has become commonplace in this administration, as even Politico’s Josh Gerstein reports.

“The Obama administration has a familiar refrain on the surveillance of Americans’ telephone records: the president and his team are eager to have the debate,” Gerstein wrote last week. “Eager, that is, only after others have brought the tactics to light and the administration has spent years employing them.”

When the news broke last week, the administration was forced to respond.

“The president welcomes a discussion of the tradeoffs between security and civil liberties,” White House spokesman Josh Earnest said. “There are people who have a genuine interest in protecting the United States and protecting constitutional liberties, constitutional rights and civil liberties that may disagree about how to strike this balance. We welcome that debate.”

So do we. But it shouldn’t be anything like what normally passes for debate in Washington — endless posturing, no clash of real ideas and positions, and no progress on an issue once the speeches are over.

Instead, let’s debate a simple proposition: Whether the NSA’s actions constitute a violation of the Fourth Amendment, which requires that government get a warrant before conducting a search.

Let’s set aside, at least for now, the whistleblower himself. Edward Snowden is not the issue here. Whether he’s “a hero or a traitor” is beside the point. The much larger issue is where we set the balance between security and privacy.

Another rule for this much-needed debate is that both sides must agree the Constitution is the last word. If one side is arguing the NSA must be bound by the Constitution, and the other side is arguing the Constitution itself is outdated, then they’re having two separate arguments.

Obama himself cited the primacy of the Constitution, when he weighed in against the Bush administration’s domestic spying activities in 2008, when he was still a senator.

So we can all agree to that.

Next, the debate must be a reasoned discussion.

“You can’t have 100 percent security and also then have 100 percent privacy and zero inconvenience,” Obama said last week.

He’s right. But he’s also presenting American citizens with a false dilemma. It’s not a matter of 100 percent of anything. It’s a matter of reasonable people talking about reasonable limits on both security (in the interest of privacy) and privacy (in the interest of security).

And neither side should be allowed to simply say, “trust us.” That’s the end of real debate, not the beginning.

Finally, the debate must lead to real action to improve the NSA’s practices. This is a rare moment of bipartisanship — in that member of both parties have taken both sides of this issue. The ACLU, for example finds itself at odds in Sen. Diane Feinstein.

So let’s have this debate. And then let’s do something about it.