You need benchmarks with the following three properties: 1) No known solutions, so there's no "ground truth" dataset to train on 2) Presumably hard to solve

You need benchmarks with the following three properties: 1) No known solutions, so there's no "ground truth" dataset to train on 2) Presumably hard to solve 3) But easy to verify a solution if one is provided. This, of course, is easier done on the STEM side of things, but how do you automatically test creativity, or philosophical aptitude?