When I was an undergraduate, I remember one of my (English Lit) professors saying on the first day of class: "There is no such thing as a stupid question." Obviously, this was a warm-and-fuzzy attempt to impart some measure of confidence to students, to encourage us to voice our questions and concerns without reservation, and to let us know that seminar discussions would be open and non-judgmental. The very first time I taught my own class at Penn State--five years ago now-- I said the same thing on the operning day of class.
Then I got a lot of stupid questions.
Nowadays, I don't believe that little credo about "no stupid questions" anymore. There are such things as stupid questions. These include (but are not limited to): questions of fact about things that are in the assigned reading, questions about the structure/schedule/requirements of the course that can be found in the syllabus, questions like "does spelling count?" or "can I get partial credit [for my incorrect answer]?", and questions about the course material that are some variation on "who cares what [Philosopher X] thinks?". I just cannot take any of these queries seriously, and I have resigned myself to responding with incredulous eye-rolling, sighing, and feigning utter skepticism about the fate of humanity.
That said, I've noticed there are a lot of questions that I get in class that appear at first to closely approximate a bona fide stupid question but, upon further consideration, are actually really astute and intuitive inquiries. I like to call these the "simple-cum-brilliant" questions. What's great about these questions is that they remind me what it was like before I read whatever material we're discussing in class, what sorts of propositions and analyses seemed, at first, completely strange to me, what there is in the material that is not immediately apparent, and how the things that "everyday" or "natural" consciousness of the world seems to intend might be at odds with what's in the book. I also like these questions because they force me to articulate clearly propositions that I (now) take to be intuitively true, but which are in fact counterintuitive (and probably seemed that way to me at one time, as well). So, for example, when a students asks me: what do you mean 'race is not genetic'? or how can 'impossibility' be the condition for the possibility of 'possibility'? or why can't I know that my experience of consciousness is exactly the same as everyone else's experience of consciousness?... then I am forced to acknowledge (to myself, anyway) that the answers to these sorts of questions have a lot of prerequisites, and that those prerequisites most often include whatever text we're reading.
These sorts of questions are the kind that really test the mettle of a philosophy professor, in my view, because they force us to get outside of our comfort zone and explain/defend complicated philosophical arguments in what Rorty called "good old plain American English." I know I've been hyping my practice of blogging in the classroom a lot lately, but I think the class blogs are great fora for working through just these sorts of issues. This semester, my Philosophy of Race course blog is a case in point. I can actually see the nuts-and-bolts process of students' working-through of a host of "simple-cum-brilliant" questions. (Want to see a really superlative example of students working through issues themselves? See this conversation from the Race blog.) They're asking things that, perhaps unfortunately, I stopped asking a long time ago: what is 'racism'? what is the difference between a 'race' and any other group? in what sense is race 'real'? These are not only not "stupid" questions, but they're not even "simple" questions, really. They're the sorts of questions that, if answered to some satisfaction, can really switch on that metaphorical light-bulb that we all wait to see lit in our classes.