Freemindfade: The "fire in theater" is often cited as an example of the limits of free speech. This is indeed a limit on free speech as it defines a class of "banned speech"; i.e. speech which present a clear and obvious danger. You bring up the periphery issue that speech (yelling) is not allowed in a theater to begin with; this is true, but it is easy to imagine a similar situation in a public venue or a private venue which just happens not to have any such laws. Should it be allowed to (knowing the outcome) yell "fire" in such a setting?
By the way, please wait for me to re-define speech in some technical manner before bringing this issue up; also, I am not in favor of "banning everything". I am discussing your suggestion there should be no limitations to speech.