Professor Yoshino explains. "Shakespeare calls this a problem of ocular proof, the idea that we need to see evidence before we believe in it -- and that,oftentimes, when metaphysical questions of guilt or innocence are difficult for us to answer, we have a tendency to reduce them to questions that pertain to physical evidence.

VOA: special.2011.06.06

But is this going to be a problem for people trying to communicate in Iran?

VOA: standard.2010.06.15

"Republicans are not interested in working with Democrats to fix this problem.

VOA: standard.2009.07.21

"In the long run the only real way to solve this problem is to make sure that we've got a Palestinian state side by side with an Israel that is secure."

VOA: standard.2010.06.10

"We have to do this because it's a problem that is today in Greece, but if we don't fix it in Greece it may have a lot of consequences on the rest of the European Union."

VOA: standard.2010.04.28

"We in the Congress have a duty to tackle this problem, but the solution we settle upon should not be rushed, and the solution should not be worse than the problem we are trying to solve,".

VOA: standard.2009.10.10