René Descartes Poses a Language Test for Machines

Centuries before the Turing test, we have the Descartes test. In René Descartes' Discourse on the Method published originally in 1637, as the preface to three essays; an English translation followed in 1649.

In its fifth part he imagines machines built to look and move like humans and gives two tests that would still expose them, saying: "For we may easily conceive a machine to be so constructed that it emits vocables, and even that it emits some correspondent to the action upon it of external objects which cause a change in its organs; for example, if touched in a particular place it may demand what we wish to say to it; if in another it may cry out that it is hurt, and such like; but not that it should arrange them variously so as appositely to reply to what is said in its presence, as men of the lowest grade of intellect can do."

So Descartes had two tests. The first is language. Such a machine might respond in human-like ways but Descartes was skeptical that such a machine could ever arrange their responses generally. The second is versatility across all of life's tasks. Natural language processing and conversational programs dating back to Joseph Weizenbaum’s ELIZA and including today’s LLMs still answer to Descartes bar: replying sensibly to whatever is said.