I agree. As usual, the key question is what are you trying to accomplish. To win? To socialize? To have an interesting game? If you are playing a friendly game, and an interesting position develops, and then your opponent makes a huge and immediately obvious blunder, there's something to be said for letting him retract his move. There's something unaesthetic about an interesting game -- hard fought and well played on both sides -- which is won because of a stupid move. I suppose Sirlin's response would be to suggest you have a clear idea in your head at the beginning of what you are trying to accomplish; and to try to avoid from changing that objective after the fact in order to save face. One could observe that in most competitions, there are a lot of objectives besides just winning the competition. For example a runner up on America's Top Model who nevertheless lands a modeling contract due to her exposure on the show.