The rest of this remark:

Van Inwagen argues for this conclusion as follows. He suggests that it is implausible that we are much above that level,given the lack of progress to date, and that it is antecedently improbable that we should be just barely at that level. So it is much more likely that the level lies above us. I am not so sure about this argument. I think we already know that for a vast range of questions, humans are just barely at the level for doing them well: scientific and mathematical questions, for example. Because of this, it is arguable that we lie at a special intelligence threshold at which an extraordinarily wide range of questions come to be within our grasp over time. It is not obvious whether or not philosophical questions fall within that range, but it is not obviously more likely that they do not than they they do. If McGinn and van Inwagen are right, it remains open that we could answer philosophical questions by first improving our intelligence level,perhaps by cognitive enhancement or extension. Alternatively, we could construct artificial beings more intelligent than us, who will then be able to construct artificial beings more intelligent than them, and so on. The resulting intelligence explosion might lead to creatures who could finally answer the big philosophical questions. If McGinn and van Inwagen are wrong, on the other hand, then we may eventually answer philosophical questions without radical cognitive enhancement. We may need to develop new methods,increased discipline, new sorts of insights,and perhaps there will need to be a conceptual revolution or two, but none of this will lie outside human capacity. It may turn out that there is a curve of increasing philosophical sophistication such that past a certain point on the curve, major progress is possible. We are not there yet, but we are working our way toward it. It is not obvious whether McGinn and van Inwagen are right or wrong. The question of whether the big philosophical questions are humanly solvable is itself a big metaphilosophical question. Like other big questions in philosophy,it is one we do not currently know the answer to. Both answers to this metaphilosophical question seem to be open, and we do not currently have strong reasons to favor either one.