The authors begin by distinguishing between two basic types of intentional behavior, which they call polimorphio actions and mimeomorphic actions. Polimorphic actions (such as writing a love letter) are ones that community members expect to vary with social context. Mimeomorphic actions (such as swinging a golf club) do not vary. Although machines cannot act, they can mimic mimeomorphic actions. Mimeomorphic actions are thus the crucial link between what humans can do and what machines can do.

Following a presentation of their detailed categorization of actions, the authors apply their approach to a broad range of human-machine interactions and to learning. Key examples include bicycle riding and the many varieties of writing machines. They also show how their theory can be used to explain the operation of organizations such as restaurants and armies. Finally, they look at a historical case -- the technological development of the air pump -- applying their categorization of actions to the processes of mechanization and automation. Automation, they argue, can occur only where what we want to bring about can be brought about through mimeomorphic action.