Unit 1: THE INTERNET AND OTHER ADDICTIONS Style: Challenging an Argument The following are special expressions that we use to challenge each otherís ideas.   Expressions for Challenging an Argument  I'm sorry, but I'm afraid you're missing the point. No, I believe that's really not true. So what exactly are you talking about? In the case of . . . , this is simply not so. I find this really hard to believe. What you don't seem to fully understand is . . .