I accept a share of the world as it comes to me. Some of it seems impervious to doubt: certain truths – vacuous, brute, and otherwise. There are coils from which the mind cannot unwind itself. And these too encourage doubt.
Nor am I speaking of a metaphysical or ontological doubt. Not knowing the details is different than doubting the mere fact of something. I could doubt my senses,experience and innate perspective; but not that I am someone doubting. I am here in some permutation of being. I may not know the fabric or the weave but I know that I am wearing it.