Cartesian agent-environment boundary

A Cartesian agent setup is one where the agent receives sensory information from the environment, and the agent sends motor outputs to the environment, and nothing else can cross the “Cartesian border” separating the agent and environment. If you can eat a psychedelic mushroom that affects the way you process the world—not just presenting you with sensory information, but altering the computations you do to think—then this is an example of an event that “violates the Cartesian boundary”. Likewise if the agent drops an anvil on its own head. Nothing that happens in a Cartesian universe can kill a Cartesian agent or modify its processing; all the universe can do is send the agent sensory information, in a particular format, that the agent reads.