TL;DR: Your discernment in a subject often improves as you dedicate time and attention to that subject. The space of possible subjects is huge, so on average your discernment is terrible, relative to what it could be. This is a serious problem if you create a machine that does everyone's job for them. See also: Reality has a surprising amount of detail. (You lack awareness of how bad your staircase is and precisely how your staircase is bad.) You don't know what you don't know. You forget your own blind spots, shortly after you notice them. An afternoon with a piano tuner I recently played in an orchestra, as a violinist accompanying a piano soloist who was playing a concerto. My 'stand partner' (the person I was sitting next to) has a day job as a piano tuner. I loved the rehearsal, and heard nothing at all wrong with the piano, but immediately afterwards, the conductor and piano soloist hurried over to the piano tuner and asked if he could tune the piano in the hours before the concert that evening. Annoyed at the presumptuous request, he quoted them his exorbitant Sunday rate, which they hastily agreed to pay. I just stood there, confused. (I'm really good at noticing when things are out of tune. Rather than beat my chest about it, I'll just hope you'll take my word for it that my pitch discrimination skills are definitely not the issue here. The point is, as developed as my skills are, there is a whole other level of discernment you can develop if you're a career piano soloist or 80-year-old conductor.) I asked to sit with my new friend the piano tuner while he worked, to satisfy my curiosity. I expected to sit quietly, but to my surprise he seemed to want to show off to me, and talked me through what the problem was and how to fix it. For the unfamiliar, most keys on the piano cause a hammer to strike three strings at once, all tuned to the same pitch. This provides a richer, louder sound. In a badly out-of-tune piano, pressing a single key will result