Is this is the correct definition you meant to utilize, "The argument tries to defend a position by showing that its shortcomings are shared by the opposing position. In effect, the argument says, 'My position may be bad, but you should accept it because my opponent's position is just as bad.' ?" If you are intending to apply that as a critique of my conversation with someone else, perhaps it would apply if I was using a specific argument about a specific fault, but as a generalization in application it becomes nonsensical. My generalization in application is saying, for example, a fan watching TV may criticize the Coach but does not coach themselves.