Jeff has a wooden head. It sits behind his desk, and sometimes people talk to it.
More often, people come to Jeff’s desk and talk to the head that sits on his shoulders. Jeff maintains that it’s often just as useful to talk to the wooden head as to the flesh-and-blood one! This is because, usually, going to talk to Jeff’s Head is a version of going up the mountain to talk to the hermit: we go as much to hear words of wisdom from the hermit as to hear ourselves think.
One of the most effective ways to learn something is to teach it to somebody, and one of the most effective ways of finding and fixing a bug (whether in software or any other formal explication) is to explain what’s going wrong to somebody who’s outside the problem. An archetypical whiteboard experience is to start drawing the problem for somebody, and to suddenly notice that there’s implicit whitespace labeled “Magic Happens Here.” The Ah-ha! moment is just as frequent as the Oh, DUH! moment.
I think that, in addition to wooden heads, all cars should be equipped with voice recorders. Lawyers bill huge swaths of time with a Dictaphone behind the steering wheel. Why shouldn’t everybody treat this long block of solitude, mostly free from interruption, as a signal opportunity to innovate and problem solve with somebody much smarter than ourselves? A wooden head that not only bestows enlightment but also records the conversation? Now that’s useful!