Some folks like to ask the tough questions.
Me, I like to ask the easy questions. Questions like: "What exactly is the Middle Class?"
As a general rule, I think it's been a term left intentionally vague for convenience and political purpose because a majority of Americans identify themselves as "Middle class." And if you're a political figure, it's usually best to just refer vaguely to the broadest number of people without being to specific, especially when you're talking about creating policies that help Them...the Middle Class.
Traditionally, the Middle Class has been a term distinct from the "working class" and used to refer to folks working a skilled labor job, such as doctor or lawyer. Usually folks with a college degree. Some have used "middle class" to refer to people whose jobs have a high degree of autonomy. As in, they're making decisions rather than following instructions.
But that really doesn't seem to fit the current colloquial usage of the term "middle class."
For example, when Arianna Huffington wrings her hands about the shrinking Middle Class in her new book "Third World America", most likely she's not fretting about a collapse in quality of life for Doctors, Dentists, Lawyers, and upper management.
Or when some folks claim that the domestic auto industry Invented the Middle Class...they're clearly not talking about dentists and lawyers...they're talking about line workers making a decent wage.
In modern usage, the term "middle class" seems more to refer to a certain QUALITY of life.
Something in the Middle:
Middle class is a life where you have to budget your money wisely, but a life where figuring out how to procure the basic necessities of life isn't a central focus of your time.
That, to me, is Middle Class.
When you find yourself spending most of your time trying to figure out how you're going to keep health insurance, stay in your modest home, and buy enough food to feed your family....you may be on the road away from "middle class" heading in the opposite direction of Rich.
Folks like Huffington, Senator Bernie Sanders, and many others have been worrying lately about what they see as a shrinking of the middle class. More and more people are moving into the "poor" column, even as more and more money is filtering over to the "rich" column.
While the top 1% of Americans hold a greater percentage of America's wealth than they've ever held before, taking 2/3 of America's economic gains from 2001 to 2007, America's poverty rate is on the rise, higher than it's been since the 1950s.
A shrinking middle class means simply More Americans are now POOR, rather than Middle Class.