No one really knows where the term "red herring" came from, though some speculate it came from the idea that drawing a fish across your path would confuse the dogs tracking you. In epistemology, a red herring is an:
Argumentum ignoratio elenchi
Literally, an "argument of ignorance of the grab," or an argument of irrelevant conclusion that doesn't fit into the other categories. A person using a red herring will attempt to draw the argument away from anything relevant with a distraction.
For examples, I will point to our country's greatest source of fallacies of irrelevant conclusion:
"Intelligence agencies should never have allowed this fake news to 'leak' into the public. One last shot at me.Are we living in Nazi Germany?" Blaming the media ("fake news") is a red herring. Invoking Nazi Germany is offensive—and also a red herring. Both attempted to turn discussion away from the contents of the "leaks" on to a discussion of the media, and who knows what else.
"All Republicans support people with pre-existing conditions, and if they don’t, they will after I speak to them. I am in total support. Also, Democrats will destroy your Medicare, and I will keep it healthy and well!" To deflect attention from the Republican Party's explicit opposition to mandating insurance companies cover people with pre-existing conditions, the third sentence drags an (equally false) red herring across your path. (Note that lies may take the form of fallacies of irrelevant conclusion, but they may also present a valid argument. We'll look deeper at the distinction between truth and validity later in this series.)
"Despite the negative press covfefe". Whatever this meant, it distracted people from an actual, substantive policy discussion policy for almost a week.
When someone uses a totally irrelevant statement to deflect from the argument you're actually having, call them on it, and don't get taken in.