Of course, just referring to animals, robots, and intelligent software packages
as “agents” doesn’t make the correspondences between intelligence any
clearer. One helpful way of seeing correspondences is to decide the level at
which these entities have something in common. The set of levels of com
monality lead to what is often called a computational theory88 after David
Marr. Marr was a neurophysiologist who tried to recast biological vision
processes into new techniques for computer vision. The levels in a computational
theory can be greatly simplified as: