A tool that everybody should be familiar with and, in fact, people use it all the time, is reductio ad absurdum arguments.  It’s the sort of general purpose crowbar of rational argument where you take your opponent's premises and deduce something absurd from them. That is, you deduce a contradiction officially.  

We use it all the time without paying much attention to it.  You may say something like "If he gets here in time for supper, he’ll have to fly like Superman" - which his absurd. Nobody can fly that fast.  You don’t even bother spelling it out. You point out that something that somebody imagined or proposed has a ridiculous consequence.  So then you go back and throw out one of the premises – whichever one is applicable.  

So that’s been known and named for several millennia, and as I say, it’s the workhorse of philosophical argumentation.  And it has a partner which is a rhetorical questions.  If you look closely you’ll see that rhetorical questions are almost always just shortened reductio ad absurdum arguments.  They imply a reductio.  When you ask a rhetorical question with that sort of yucky, sneery way, you’re saying, "Wouldn’t that be ridiculous.  I don’t have to pause for a moment to refute that."  You ask the question and you don’t expect it to be answered because the answer would be embarrassing.

One of the tools that I suggest in my book is to use that fact to find the weakness in a lot of arguments.  When someone uses a reductio or uses a rhetorical question, they are, in effect, saying this isn’t worth your time or mine to look at closely.  This is so obvious I can just make a sort of joke out of it.  Pause.  Be obstreperous and take a good look at it and see if you can answer it.  Sometimes just answer the rhetorical question.  Ask, “Why not?  I think I can actually answer this."  And this is a great way of upsetting the apple cart sometimes.   

In Their Own Words is recorded in Big Think's studio.

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