If you ask 10 different people what they think democratic socialism is, chances are you’ll get 10 different answers.

We reached out to the Sanders campaign, but didn’t hear back.

So, I asked two political science professors to define democratic socialism.

Samuel Goldman, an assistant professor of political science at George Washington University, told me it was, “achieving collective control of the economy.”

And Andrei Markovits, a professor of political science at the University of Michigan, said democratic socialism is an attempt to create, “a property–free, socialist society.”

So everything is communally owned.

Senator Sanders has touched on democratic socialism in stump speeches, like this one in Iowa last month:

“When you call your fire department or the police department, what do you think you’re calling?” Sanders asked the crowd. “These are socialist institutions.”

That Sanders attempt to use fire and police departments to define democratic socialism does not sit well with Professor Markovits.

“If he were to write this on an exam for me? That’s an F,” Markovits said.

Sanders has also cited Denmark as a place where democratic socialism has worked.

That gets a rise out of Professor Goldman. With apologies to Shakespeare, he said there’s something rotten in Sander’s assertions about the state of Denmark.

“I would not call that socialism,” he said.

Or even democratic socialism. Professor Markovits agrees. Ultimately, Markovits said, there’s no private property at all under democratic socialism. He said it doesn’t exist in Denmark or anywhere else, and is an unattainable goal.