CONCEPT
The Mill Argument
Leibniz’s 1714 thought experiment—walk inside a thinking machine enlarged to the size of a mill and you will find only parts pushing on parts, never the perception—the earliest and still most precise statement of the hard problem of machine consciousness.
In the seventeenth section of his
Monadology, Gottfried Wilhelm Leibniz asked us to perform a thought experiment that three centuries of philosophy and engineering have not made obsolete: suppose a machine so constructed as to think, feel, and have perception. Enlarge it, keeping the same proportions, until it is the size of a mill and you can walk inside it as you would enter a building. Walking through its interior, you would find only parts working upon one another—gears, levers, the flow of motion—and never anything that would explain a perception. From this inspection Leibniz concluded that perception must be sought not in mechanism but in the simple substance, the monad, that no machine could be. The argument appeared in the context of seventeenth-century debates about
consciousness and mechanism, but it is now the foundational text of the
hard problem of consciousness as that problem applies to artificial systems. A
neural network is, quite