When someone argues by analogy, you can be pretty sure it’s because they don’t have any facts, evidence or logic to support their position. And all you have to do to debunk their argument, is find the flaw in the analogy.It ties in nicely with a similar idea about the use of metaphor's
Be Careful Believing Your Own Metaphors:
I've cautioned students against using metaphors; though they make writing more vivid, and sometimes more persuasive, they often obscure more than they reveal. Part of the problem is that they are literally false -- if they were true, they wouldn't be metaphors. Sometimes the literal falsehood reveals a deeper truth, but sometimes it's just plain false.