Sometimes these ideas are facts, such as: 1 apple + 1 apple = 2 apples. We can easily see this by taking one apple from Johhny and another from Suzie (if either resists beat them up and tell them it is for science damnnit!). We can then look and see that we have two apples.
Some of the ideas we have are based on facts such as: 1 hippopotumus + 1 hippopotumus = 2 hippopotumus. No matter how much we beatup Johhny and Suzie, they have no hippos to give us. But based on what we know about apples and other things we formulate an idea about the addition of hippos.
Sometimes our extensions are wrong: 1 litre of alchohol plus one litre of water = 2 litres of solution. No need to beat up either Johhny or Suzie (unless you are feeling mean) tap water and rubbing alchohol will do. Fill up a nice fairly accruate measuring device and you will find out you have less than 2 litres. Depending on the tempurature alot less.
So we learn these assumptions can be proven wrong. No big deal we still make lots of assumptions. Someone one said "People think, because they don't know". I think it is a pretty cool quote. Sometimes we even find out what we thought was fact is even wrong.
I like to think of 'opinions' as things that we either think we know or have come to some conclusions about, or even are just wild guesses. However one requirement about an 'opinion' in my opinion is that you can be swayed from an opinion with by being presented with fact or logic. When you have an 'idea' that you cannot be swayed on, I use the word 'faith'. People have 'faith' in God, people have 'faith' in the aftelife. People have 'faith' that that homosexuality leads to child moslestation and devil worship. Granted you can lose faith, but at some point you totally beleive you cannot be swayed.
So think of what you consider an opinion, can you be swayed? Or perhaps it is really your faith. What do you have faith in?
George Bush is evil and will kill US Soldiers so his cronies will get wealhier?
Osma Bin Laden will kill us all next year?
Iraq has nuecluar capabilities and will nuke us first chance?
I try not to have faith in such things, just strong opinions.