Passage 1
And here I specially stayed to show that, were there such machines exactly resembling organs and outward form an ape or any other irrational animal, we could have no means of knowing that they were in any respect of a different nature from these animals; but if there were machines bearing the image of our bodies, and capable of imitating our actions as far as it is morally possible, there would still remain two most certain tests whereby to know that they were not therefore really men. Of these the first is that they could never use words or other signs arranged in such a manner as is competent to us in order to declare our thoughts to others: 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.
Machine minds and made personsCognition, attention, and judgmentmeaning and understanding · advancescalculation is insufficient · advancesMetaphysics of mind and lifeMeaning, experience, and interpretationNo judgment offeredIndividualMachine or artificial systemMind and body
Descartes makes context-sensitive expression of thought, rather than outward resemblance or a stimulus-bound vocal response, the test that a humanlike machine cannot meet.
Part V, tests distinguishing a machine from a human being