How is this so? Surely, as a general proposition, ignorance and intention are much more loosely correlated than the quote suggests. What if the statement were altered slightly: "If (after great effort and/or reflection and/or prayer) you (still) don't know..." Does it still make sense to speak of intention? Or if the point is that the failure to solve a simple problem indicates a will to fail, well then the author has more faith in human will than I do--and IMO greatly underestimates the possible ways of not-knowing.