From wikipedia, “Pair programming (sometimes referred to as peer programming) is an agile software development technique in which two programmers work as a pair together on one workstation.” It can also be viewed as an additional element of safety where one person is observing what another is doing to ensure quality and correctness. This same idea can be applied in commercial aviation where one pilot is responsible for flying the plane and the other observes what is being done as well as the environment outside the aircraft.
The subject of a future single pilot airliner cockpit comes up regularly now and there are numerous debates on safety vs cost savings. While automation can alleviate some aspects of the flying of the aircraft there are other aspects that I am not sure automation can replace having another pair of eyes and a brain available in the front office. The following link is to an example of where a second set of eyes that were solely responsible for looking and checking turned out to be the safety factor that likely avoided an accident. In this case the first officer noticed a vehicle on the runway as they touched down. The FO said to go around and they made it. Had there been only a single pilot that was busy landing and started the thrust reverser deployment before seeing the vehicle the result would likely have been bad. http://avherald.com/h?article=4825e1c3&opt=0