For me, pencil and paper works best to clarify an uncertain idea; the type of idea that may be a single sentence in a notebook, “A story about how we cannot see the forest for the trees sometimes.”
There are often more bad ideas than good ones to begin with when an idea is this unformed. If I try to flesh this idea out on a computer via a word processing tool or a tablet, bad ideas are instinctively and easily erased. And if they are erased, are they also easily forgotten? And if they are forgotten, does it become easier to generate the bad idea again? To revisit old ground? To feel that progress is slow and circular?
With marks on paper, bad ideas remain visible. The page begins to reveal a map of paths that lead to dead ends. With more visibility of the bad paths, is it easier to find the good one? The right one?