Russell Roberts mulls over the factors that determine wages:
[Douglas] Baird points out that one of the obsessions of Henry Ford was to improve the precision of the parts of a car sufficiently so that unskilled people could assemble a car. When the parts were not machined precisely, there was a highly skilled highly paid worker called a fitter who was able to get the imperfect pieces to mesh. So was better precision a good thing or a bad thing? In the box view of the world, it was bad. America lost the high-paying jobs, the jobs for fitters. But in the forehead view of the world, the world where wages depend on human capital (skill, knowledge and knowhow), Ford’s improvement was good for the world. By finding a more efficient way to make cars, wealth was created. The people who were once fitters went on to do new things, new things that were possible partly because people now had more resources available that were once spent on assembling cars.
To find out what all this forehead and box talk is about, read the whole post.