An interesting discussion, and you all make very valid points. Here in the UK some of the folks I work with still make the traditional distinction between copy-editing and proofreading that dates from the days of hot metal. However, the terms are becoming blurred, and this is causing some confusion.
This confusion become damaging when it results in a final production process that misses the fact that the proofer has no content knowledge. It also leads to the question of whether *copy-editing* can be performed in any effective way by someone without content knowledge: my contention is 'no', but in fact this is often what happens... 'copy-editing' is confused with 'proofreading'. I believe that it *is* possible to effectively edit and proof your own work, but it is hard, and requires a substantial mind-shift. I agree that it is certainly not desirable, but sometimes it cannot be avoided for cost or other reasons. Story: some time ago I was commissioned to write a book. After writing it, I lightly copy-edited it as time allowed. The publisher then sent the Ms to a trained freelance proofreader (or, as I thought, copy-editor). I applied their corrections. Some time later I was reworking the material and found some glaring errors, so I carried out a complete reproof and analysis. I was quite shocked at the number of undiscovered errors I found. Some were typos, some were technical. It turned out that the proofreader had little or no understanding of the content. I suppose the moral is that sometimes things don't turn out as you expect even if you do everything 'right'. -- Steve