First Amendment to the United States Constitution—
"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."
Freedom of speech... one of the many rights we enjoy living in this country of ours. Freedom of speech, of thought, and to believe in whatever we want to believe in. But that's not to exclude the thoughts and opinions of others. Just because we live in a country where we can exercise this freedom just about wherever we are (with professional atmospheres and general tact taken into consideration) does not mean that we are safe from the opinions and thoughts of others."Every man is a fool in some man's opinion" -Spanish proverb
"People do not seem to realize that their opinion of the world is also a confession of their character." -Ralph Waldo Emerson
"Opinion has caused more trouble on this little earth than plagues or earthquakes." -Voltaire
"Do not fear to be eccentric in opinion, for every opinion now accepted was once eccentric." -Bertrand Russel
"The fact that an opinion has been widely held is no evidence whatever that it is not utterly absurd." -Bertrand Russel
Just because you have an opinion, does not mean you are right in your opinion. That's not to say that you are not allowed to have that opinion, but that the basis for which you came to that conclusion may be as unstable as a sandcastle on the beach with the tide coming in.
Any time you state your opinion, wherever you are, you are going to have people that agree with you. At the same time you will have those who differ in opinion, and they, based on the subject matter, may choose to interject and state what they think. At this point, if the conversation continues, it is no longer an exchange of opinions, rather it has become a discussion (and sometimes an argument) as to why your opinion is more valid than the next persons. This is where it becomes crucial that you know where you are coming from in your opinion, lest you get trashed up one side and down the other about how you are wrong. Having facts to back up your statements is a key ingredient here, because you can be a bit more involved in the rebuttal, rather than just shutting down and repeating yourself like a broken record about how "It's my opinion and I can think how I want!" That's when you come off as annoying and uninformed, just spewing blanket statements out of your mouth that you heard once or twice from here or there.
I could say the sky is blue. And there will be those around me that agree with me, and there will be that one person who will swear up and down that the sky itself is not blue, but rather it has to do with the atoms of nitrogen and oxygen in the atmosphere having a different effect on the sunlight that passes through them. There is a physical phenomenon called Rayleigh scattering that causes light to scatter when it passes through particles that have a diameter one-tenth that of the wavelength (color) of the light. Sunlight is made up of all different colors of light, but because of the elements in the atmosphere the color blue is scattered much more efficiently than the other colors. When you look at the sky on a clear day, you can see the sun as a bright disk. The blueness you see everywhere else is all of the atoms in the atmosphere scattering blue light toward you. Because red light, yellow light, green light and the other colors aren't scattered nearly as well, you see the sky as blue.
He might come off as a bit pompous and a know it all if he came in on the conversation out of the blue, but for the sake of argument, let's just say they were all sitting around a table having a few drinks and had been talking to each other for the past hour.
Now I could say, "Hmm, that's interesting I'll have to look that up," and be done with the conversation. Or you could snap back at that person saying, "Well I don't believe in your hocus-pocus talk about how a yellow sun can make the clear sky look blue, all I know is when I look up I don't see any other color but blue so you're wrong!" Who would you want to stay and have a conversation with, someone who takes what someone else says with some consideration, and continues the conversation in a respectful manner, or someone who wont even give you the time of day if you differ in opinion from them?
I think that's an easy choice.
For now... life goes on.