There’s more than one house on the gated property Bob Shillman lives on -- in Rancho Santa Fe, a San Diego suburb that is one of the richest communities in America. Shillman’s main house is a mansion of stone floors, plush furnishings and soaring windows.

In person, Shillman is clever and boisterous. And he makes no apologies for his opulent surroundings. He says he earned it.

“The people that I know, and I know many businessmen, they were not handed things,” said Shillman. “They did build this. I built this company. I profited, my investors profited, and all my employees.”

America is not supposed to be class-based society. But we have always had the rich and the poor, and the gap between them is growing. The rhetoric of this election year often boils down to the question of whether the American Dream of social mobility is still a reality.

In San Diego, it’s an ongoing debate on both sides of the income gap.

Shillman is the founder of Cognex Corporation, which makes small computers that control manufacturing tools. At age 66, he says he lived the American Dream. His dad ran a small retail store in a run-down part of Boston. And he says if anything is hampering social mobility in the U.S., it’s government regulations that make entrepreneurship difficult.

Asked about the widening gap between rich and poor, he’s not sure he accepts the premise of the question.

“I think the definition of poor today is they don’t have a 50-inch flat-screen TV,” he said. “How can you be poor, Tom… how can you say somebody is poor if they have a cell phone?”

Kathleen Krantz, 64, has a cell phone. She also lives in her car. Krantz gravitated to San Diego from northern California along with two college-aged children. Her daughter is going to community college, and she’s also homeless.

“Daughter is living in her car. We park next to one another every night. We watch over each other,” said Krantz.

Krantz grew up poor near the Oregon border, where her stepfather sorted potatoes and drew unemployment. When asked how she came to be homeless, Krantz tells of many mishaps, including being diagnosed with ovarian cancer. She said her divorce -- after 20 years of marriage -- left her with little for retirement.

“Because I was a wife and didn’t work, and didn’t build my Social Security because I thought I would be married still, I ended up with a very mere $288 in Social Security benefits,” she said.

Back at Rancho Santa Fe, Marianne McDonald lives in a dark, sprawling house that’s showing its age. Unlike Shillman, McDonald inherited her wealth from her father, who was a co-founder of Zenith Corporation.

Her view of the income gap is also different. 

“I think there’s an obscenity in the world’s concentration of wealth. And I’d love to do my bit toward it, but it’s so hard for an individual to figure that,” she said.

Both McDonald and Shillman have given much of their fortunes to charity. And at age 75, McDonald still teaches classics at U.C. San Diego. She said Aristotle distrusted the poor and the rich because he believed, the former would do anything to better themselves, and the latter fell victim to power madness.

But if a large middle class is the ideal, San Diegan Hafsa Mohamed doesn’t see that happening in America’s bifurcated economy.

The daughter of Somalian refugees, Mohamed comes from a low-income family in City Heights, an inner city neighborhood that is home to many immigrants. Her mother had to work two jobs to support six children after her husband was deported for immigration fraud. Thanks to student loans, Mohamed is attending San Diego State University.

She says American society is stacked against social mobility.

“Right now there’s just none of that. There people looking down and people looking up and there’s tons of barriers,” said Mohamed.

Bob Shillman disagrees.

“Everybody in this country has opportunity,” said Shillman. “What’s important is to rise above the thought that you are doomed to poverty.”

That second statement is something most people agree on. Despite her low-income childhood, Mohamed says she will pursue her Ph.D. Krantz says her children will have a college education, and they will do better than she has done.

“I wanted them to set their star up there and grab for it, whatever it is,” said Krantz.

Call it the American Dream, but living without it is living without hope. And that’s something nobody wants.