June 16th, 2012
Image of the statue of the Golem of Prague at the entrance to the Jewish Quarter of Prague by flickr user D_P_R. Used by permission (CC-BY 2.0).
Alan Turing, the patron saint of computer science, was born 100 years ago this week (June 23). I’ll be attending the Turing Centenary Conference at University of Cambridge this week, and am honored to be giving an invited talk on “The Utility of the Turing Test”. The Turing Test was Alan Turing’s proposal for an appropriate criterion to attribute intelligence (that is, capacity for thinking) to a machine: you verify through blinded interactions that the machine has verbal behavior indistinguishable from a person.
In preparation for the talk, I’ve been looking at the early history of the premise behind the Turing Test, that language plays a special role in distinguishing thinking from nonthinking beings. I had thought it was an Enlightenment idea, that until the technological advances of the 16th and 17th centuries, especially clockwork mechanisms, the whole question of thinking machines would never have entertained substantive discussion. As I wrote earlier,
Clockwork automata provided a foundation on which one could imagine a living machine, perhaps even a thinking one. In the midst of the seventeenth-century explosion in mechanical engineering, the issue of the mechanical nature of life and thought is found in the philosophy of Descartes; the existence of sophisticated automata made credible Descartes’s doctrine of the (beast-machine), that animals were machines. His argument for the doctrine incorporated the first indistinguishability test between human and machine, the first Turing test, so to speak.
Uniformly, the evidence for Talmudic discussion of the Turing Test is a single quote from Sanhedrin 65b.
Rava said: If the righteous wished, they could create a world, for it is written, “Your iniquities have been a barrier between you and your God.” For Rava created a man and sent him to R. Zeira. The Rabbi spoke to him but he did not answer. Then he said: “You are [coming] from the pietists: Return to your dust.”
Rava creates a Golem, an artificial man, but Rabbi Zeira recognizes it as nonhuman by its lack of language and returns it to the dust from which it was created.
This story certainly describes the use of language to unmask an artificial human. But is it a Turing Test precursor?
It depends on what one thinks are the defining aspects of the Turing Test. I take the central point of the Turing Test to be a criterion for attributing intelligence. The title of Turing’s seminal Mind article is “Computing Machinery and Intelligence”, wherein he addresses the question “Can machines think?”. Crucially, the question is whether the “test” being administered by Rabbi Zeira is testing the Golem for thinking, or for something else.
There is no question that verbal behavior can be used to test for many things that are irrelevant to the issues of the Turing Test. We can go much earlier than the Mishnah to find examples. In Judges 12:5–6 (King James Version)
5 And the Gileadites took the passages of Jordan before the Ephraimites: and it was so, that when those Ephraimites which were escaped said, Let me go over; that the men of Gilead said unto him, Art thou an Ephraimite? If he said, Nay;
6 Then said they unto him, Say now Shibboleth: and he said Sibboleth: for he could not frame to pronounce it right. Then they took him, and slew him at the passages of Jordan: and there fell at that time of the Ephraimites forty and two thousand.
The Gileadites use verbal indistinguishability (of the pronounciation of the original shibboleth) to unmask the Ephraimites. But they aren’t executing a Turing Test. They aren’t testing for thinking but rather for membership in a warring group.
What is Rabbi Zeira testing for? I’m no Talmudic scholar, so I defer to the experts. My understanding is that the Golem’s lack of language indicated not its own deficiency per se, but the deficiency of its creators. The Golem is imperfect in not using language, a sure sign that it was created by pietistic kabbalists who themselves are without sufficient purity.
Talmudic scholars note that the deficiency the Golem exhibits is intrinsically tied to the method by which the Golem is created: language. The kabbalistic incantations that ostensibly vivify the Golem were generated by mathematical combinations of the letters of the Hebrew alphabet. Contemporaneous understanding of the Golem’s lack of speech was connected to this completely formal method of kabbalistic letter magic: “The silent Golem is, prima facie, a foil to the recitations involved in the process of his creation.” (Idel, 1990, pages 264–5) The imperfection demonstrated by the Golem’s lack of language is not its inability to think, but its inability to wield the powers of language manifest in Torah, in prayer, in the creative power of the kabbalist incantations that gave rise to the Golem itself.
Only much later does interpretation start connecting language use in the Golem to soul, that is, to an internal flaw: “However, in the medieval period, the absence of speech is related to what was conceived then to be the highest human faculty: reason according to some writers, or the highest spirit, Neshamah, according to others.” (Idel, 1990, page 266, emphasis added)
By the 17th century, the time was ripe for consideration of whether nonhumans had a rational soul, and how one could tell. Descartes’s observations on the special role of language then serve as the true precursor to the Turing Test. Unlike the sole Talmudic reference, Descartes discusses the connection between language and thinking in detail and in several places — the Discourse on the Method, the Letter to the Marquess of Newcastle — and his followers — Cordemoy, La Mettrie — pick up on it as well. By Turing’s time, it is a natural notion, and one that Turing operationalizes for the first time in his Test.
The test of the Golem in the Sanhedrin story differs from the Turing Test in several ways. There is no discussion that the quality of language use was important (merely its existence), no mention of indistinguishability of language use (but Descartes didn’t either), and certainly no consideration of Turing’s idea of blinded controls. But the real point is that at heart the Golem test was not originally a test for the intelligence of the Golem at all, but of the purity of its creators.
Idel, Moshe. 1990. Golem: Jewish magical and mystical traditions on the artificial anthropoid, Albany, N.Y.: State University of New York Press.