The post doesn't do justice to the subtlety of Turing's insight. The Turing test is two-faced in that the interrogator is addressing two contestants, the computer and the human. He doesn't know which is which, but he hopes that comparing their answers will reveal their identities. But the Turing test is two-faced in a second way.

Turing hopes that the test will satisfy its audience, but that audience contains two groups. There is a pro-AI group. Some of them will have been involved in writing the initial source code of the AI that is taking the test. They are cheering on the AI. Then there is the anti-AI group, staunchly maintaining that computers cannot think. They admire the trickery of the programmers, but refuse to credit the creation with the thoughts of its creators.

Consider a conventional test that resembles a university examination. Perhaps the computer scores high marks. The anti-AI refuses to budge. The coders have merely hired experts in the subject being examined and laboured hard to construct a brittle facade of apparent knowledge. Let us change the curriculum,...

But a conventional test has both failure modes. If the computer scores low marks the pro-AI crowd will refuse to budge. The test was too hard and they were not given enough time to prepare. A human student would cope as poorly if you switched the curriculum on him,...

Turing tried to come up with a test that could compel die-hard in both camps. First he abolishes the curriculum. The interrogator is free to ask whatever questions he wishes. There is no point teaching to the test, for the question "Will this be on the test?" receives no answer. Second he abolishes the pass mark. How well does the computer have to do? As well as a human. And how well is that? We don't know; a human will take the test at the same time as the computer and the interrogator will not know which is which, unless the incompetence of the computer gives the game away.

The pro-AI camp are between a rock and a hard place. They cannot complain about the lack of a curriculum for the human doesn't get a copy of it either: it doesn't exist. They cannot complain that the questions were too hard, because the human answered them. They cannot complain that the human's answers were merely a good effort but actually wrong, because they were good enough to let the interrogator recognise human superiority.

The final gambit of the pro-AI camp is to keep the test short. Perhaps the interrogator has some killer questions that will sort the humans from the computers, but he has used them before and the programmers have coded up some canned answers. Keep the test short. If the interrogator starts asking follow up questions, probing to see if those were the computer's own answers, probing to see if the computer understands the things it is saying or reciting from memory,...

We come to a tricky impasse. Just how long does the interrogator get?

Perhaps it is the anti-AI crowd that is having a hard time. The computer and the human are both giving good answers to the easy questions. No help there. The computer and the human are both struggling to answer the hard questions. No help there. The medium questions are producing different answers from the two contestants, but sometimes teletype A hammers out a human answer and teletype B tries to dodge, and sometimes its the other way round.

There is one fixed point on the non-existent curriculum, childhood. Tell me about your mother, tell me about your brother. The interrogator learns anew the perils of a fixed curriculum. Teletype A has a good cover story. The programmers have put a lot of work into constructing a convincing fiction. Teletype B has a good cover story. The programmers have put a lot of work into construction a convincing fiction. Which one should the interrogator denounce as non-human. The interrogator regrets wasting half the morning on family history. Fearing embarrassment he pleads for more time.

The pro-AI camp smirk and say "Of course. Take all the time you need.". After the lunch break the interrogation resumes. After the dinner break the interrogation resumes. The lights go on. People demand stronger coffee as 11pm approaches. Teletype B grows tetchy. "Of course I'm the human, you moron. Why can't you tell? You are so stupid." The interrogator is relieved. He has coded chat bots himself. On of his last ditch defenses was

(defun insult-interrogator () (format *standard-io* "~&You are so stupid."))

He denounces B as non-human, getting it wrong for the fourth time this week. The computer sending to teletype A has passed the Turing test :-)

Whoops! I'm getting carried away writing fiction. The point I'm trying to tack on to Turing's original insight (no curriculum, no pass mark) is that the pro-AI camp cannot try to keep the test short. If they limit it to a 5 minute interrogation, the anti-AI camp will claim that it takes six minutes to exhaust the chat bots opening book, and refuse to concede.

More importantly the anti-AI camp can develop the technique of smoking out small-state chat-bots by keeping the interrogation going for half an hour and then circling back to the beginning. Of course the human may have forgotten how the interrogation began. It is in the spirit of the test to say the the computer doesn't have to do better than the human. But the spirit of the Turing test certainly allows the interrogator to try. If the human notices "Didn't you ask that earlier." and if the computer doesn't, or slows down as the interrogation proceeds due to an ever-growing state, the computer quite properly fails the Turing Test. (Hmm, I feel that I'm getting sucked into a very narrow vision of what might be involved in passing the Turing Test.)

If the pro-AI camp want the anti-AI camp to concede, they have to let the anti-AI interrogators keep asking questions until they realise that the extra questions are not helping. The computer is thinking about the questions before answering and can keep it up all day.

I think that you can break a chat-bot out of its opening book with three questions along the following lines.

1)Which is heavier, my big toe or a 747

2)Which is heavier, a symphony or a sonnet

3a)Which question do you think is better for smoking out the computer, the first or the second?

3b)Which of the previous two questions is the more metaphorical?

One can imagine a big engineering effort that lets the computer identify objects and estimate their weight. Big toe 10 grams. 747, err, 100 tons. And one can write code that spots and dodges trick questions involving the weight of immaterial objects. But one needs a big, fat opening book to cope with the great variety of individual questions that the interrogator might ask.

Then comes question three. That links together question one and question two, squaring the size of the opening book. 40 seconds into an all day interrogation and the combinatorial explosion has already gone BOOM!

a true open ended test would need to deviate from this text-based format nowadays.

Where does this leave mute humans, or partially paralyzed humans, or any other kind of human who can't verbally speak your language ? If we still classify them as "human", then what reason do you have for rejecting the AI ?

P.S.: Whether all this has to do with conscious experience ("consciousness") we don't know, I think.

The classical problem is that the Turing Test is behavioristic and only provides a sufficient criterion (rather than replacing talk about 'intelligence' as Turing suggests). And it doesn't provide a proper criterion in that it relies on human judges - who tend to take humans for computers, in practice. - Of course it is meant to be open-ended in that "anything one can talk about" is permitted, including stuff that's not on the web. That is a large set of intelligent behavior, but a limited set - so the "design to the test" you are pointing out is precisely what chatterbot people use. And it's usually pretty dumb and provides no insight into human flexibility in using language (which can be used for more than "talking about stuff"). I also suspect that we'll have passing the test pretty soon, in the sense of non-sophisticated judges. So far, results are hopeless, however! The main weakness is that the machines don't do much analysis of the conversation so far. --- Essentially, we know from similar problems (e.g. speech recognition) that one can get very good, but somewhere in the upper 90% there is a limit that's very hard to break without using more data.

Thanks, insightful post. I find the research a bit patchy. Only on the atomic bomb there is vast literature since the 1950ies, even in popular fiction - and a couple of crucial names like Oppenheimer (vs. Teller), the Russell–Einstein Manifesto or v. Weizsäcker are absent here.