We do not know everything. In fact, there are lots of things we can never know. So, how can we recognize the limits of our capacity for knowledge? What role might skepticism and the method of doubt play in helping us to delineate our limits? How do we know when to keep trying to figure something out and when it is better to give up and stop wasting our time?
Although we are in pursuit of an abstract distinction here, practical examples may help us to draw it more clearly. The responses will arise pretty naturally, as we lend our individual opinions to the project of discovering a shared understanding of our epistemological limits.