Resolved: in Great Debates, and indeed in any serious discussion, we should carefully distinguish between these three kinds of statements, as follows.
Facts are those statements that are verifiably true to a high degree of certainty. It is a fact that Obama is currently president of the United States. It is a fact that the first word in this sentence is “it.” It is a fact that Mubarak left office in Egypt in February 2011. Facts that are not well known benefit from reliable citations in GD, but the well-known facts don’t need cites. Here’s the relevant definition of fact, if you need to see what a cite looks like.
Beliefs are those statements that have a truth value, but whose truth value is debatable. I believe that Obama’s health care policies will decrease the cost of health care overall. I believe that the previous sentence follows all standard rules of English grammar. I believe that Mubarak’s ouster is due primarily to inspiration from events in Tunisia. Beliefs, especially the thesis of a GD OP or a response to a GD OP, need to be supported by facts. Again, I’ll cite the Wikipedia article to support my belief that this definition of belief is the one to use.
Opinions are those statements that express a value. Obama is a great president. My sentences are well-written, stylish, and sexy. Mubarak’s ouster was a glorious event for the Middle East. Opinions that are unsupported by beliefs or facts are fine, but they have no place in Great Debates. They’re much more interesting when supported by beliefs or facts with relevant citations: if you think that Reagan was a nasty little jerk, but you offer no evidence for your opinion, it’s really hard for me to care, whereas if you offer the opinion that he was a nasty little jerk and support that opinion with facts about the Iran-Contra connection, then we’ve got something to talk about.
This post is an example of a problem. True, the OP started in IMHO–but it’s chock full of beliefs (controversial statements with a truth value) with opinions layered on top. In order to discuss it, one must discuss the truth value of the beliefs, but when such a discussion starts, the OP insists that they were all just opinions.
Don’t do that, folks. Keep your opinions separate from your beliefs, and to the extent that you want to have a discussion, support them all with facts.