Republican presidential contender Herman Cain defended his 9-9-9 tax reform proposal on NBC's “Meet the Press” on Sunday. The interview showed the candidates adeptness at answering questions on economics, but also showed weaknesses in his understanding of foreign policy when he did not know what a neo-conservative was.

Cain has spent most of his career has a businessman and is best known as the CEO of Godfather's Pizza. He was also chair of the Kansas City Federal Reserve Board, an advisory position, and unsuccessfully ran for the U.S. Senate in 2004.

Cain's signature 9-9-9 plan would get rid of the current federal tax code and replace it with a nine percent personal income tax, nine percent corporate tax and nine percent sales tax.

One criticism of his plan is that it would give the wealthy a big tax break while increasing taxes on the poor and middle class. Cain answered that criticism by arguing that, while the poor would be paying a nine percent sales tax on goods they buy, the cost of those goods would come down due to the elimination of other taxes built into the cost of those goods.

“There are invisible taxes on everything you buy,” Cain explained, “for example, take a loaf of bread. The farmer pays taxes on his profits, the company that makes the flour, the baker, the delivery man, by the time that loaf of bread gets to the grocery store, there are a series of invisible taxes, which are also called embedded taxes, so, in reality, those taxes go away and so the price of goods do not go up.”

Cain admitted that some people would pay more in taxes under his plan. “Who would pay more? The people who spend more money on new goods. The sales tax only applies to people who buy new goods, not used goods.”

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When asked if he considers himself a neo-conservative, Cain said he did not know what a neo-conservative was.

The neo-conservative movement has been an influential force among conservatives, especially over the past decade. The movement began in the 1960s among disaffected, mostly Jewish, Democrats who felt the party was becoming too isolationist on foreign policy.

President George W. Bush was not much of a neo-conservative when he began his presidency, but turned to neo-conservative thought after the September 11, 2001 attacks. Neo-conservative views were influential in the invasions in Iraq and Afghanistan. Neo-conservatism is also known for its strong support of the state of Israel.

“I'm not sure what you mean by neo-conservative. I am a conservative, yes. Labels, sometimes, put you in a box,” Cain said.

When asked why Americans should trust him in foreign policy matters, Cain replied, “consider my philosophy on foreign policy and my principles, that's where you start. You can collect the information and make an informed decision. My philosophy is an extension of the Reagan philosophy – peace through strength and clarity.”

Cain was also asked whether he supports an exception for rape, incest and the life of the mother to obtain an abortion. “You look at rape and incest, the percentage of those instances are so miniscule that there are other options. If it's the life of the mother, their family is going to have to make that decision,” Cain said.