The title above is a quote from Robert Heinlein, and also one of the three basic premises of Science Fiction.
Today, they are also a warning to John McCain, Sarah Palin, and those people at their rallies who scream and cheer at suggestions of hate and violence. The Baltimore Sun has an editorial warning those candidates that they are walking a line that they need to cut short -- a line that is encouraging venom, hatred, and violence. This country does not need to have candidates going around acting as if their opponents are terrorists.
If this goes on, and the hate fest escalates, it could mean lives lost and mob actions. We do not need that. If this goes on, for generations the name "Republican" could become a stink in the nostrils of decent folk.
The candidates must put a stop to their craven techniques, and disassociate themselves from nascent mob behavior.
This must be stopped ... it must not go on.