Nobody asked but …
I heard on the radio this morning what I will call the Sidebar Fallacy. It is a specialized form of a hybrid between the straw man and the red herring. It is essentially an accidental getting off topic and pretending that the new topic is germane. The new topic, however, is irrelevant. There is no long-term connection to the original topic, whether the bogus topic is dispensed with either in agreement or in disagreement.
In the case which prompted me to think on this, the main topic was Harvard’s admission policy, the sidebar was whether or not somebody had explicitly said something. Yes, the speaking person had mentioned two loosely related items in what sounded like one sentence, but it was a stretch to say that the items were codependent. It made no difference, however, since formal policy is almost always written and approved before application, and should not be subject to ad hoc amendment by the vagaries of oral exposition. Having two thoughts in proximity does not establish implicitness. But this is only a sidebar. The resolution of the problem in the sidebar may or may not solve or even relate to the problem in the main process.
How does this compare to the straw man? The straw man is a deliberate choice of an off topic argument that is intended for a seeming solution which appears to relate to the main topic. The user claims that the “off” topic overcomes the main topic to become the main topic.
How does this compare to the red herring? The red herring is another distraction from the main topic, also deliberate. A open-ended tangent is pursued for the actual purpose of leaving the main topic behind. There is no attempt to arrive at an agreement. There is no pretense of applying a solution falsely back to the original dispute.
In the instant case, the difference is that one or both parties believe that the issue is pertinent, and that agreement is required before returning to the main topic. The straw man and red herring are intended for mischief — to destroy rational exchange. In the sidebar, there may be sincerity but with a failure to evaluate significance.
— Kilgore Forelle