What can the Turing Test Tell Us?

Alan Turing's contribution to mathematics, cryptography and computer science was inestimable. Not only did he shorten World War Two, saving thousands of lives, he advanced us onto the path of digital computers. His suicide after being coerced into hormone treatment is a massive blot on the intellectual landscape in Britain. It is an enduring source of shame. Turing's work remained classified for decades because of the fear that war might break out again and knowing how to break the complex codes used by the Germans was too valuable an advantage to throw away. Nowadays, cryptography has advanced to the point where keeping Turing's work a secret no longer confers much advantage.

Turing was prescient in many ways. Not only did he set the paradigm for how digital computers work, but he understood that one day such machines might become so sophisticated that they were indistinguishable from intelligent beings. He was the first person to consider artificial intelligence (AI). Thinking about AI led him to construct one of the most famous thought experiments ever proposed. The Turing Test is not only a way to distinguish intelligence, it is actually a way of thinking about intelligence without getting bogged down in the details of how intelligence works. For Turing and many of us, the argument is that if a machine can communicate in a way that is it indistinguishable from a human being, then we must assume that it is intelligent, however it achieves this. It's a pragmatic definition of intelligence and one that leads to a practical threshold, beyond which all AI researchers wish to pass.

However underpinning the test are some assumptions about communication, language, and intelligence that I wish to examine. The first is that all human beings all seem to be considered good judges for the Turing Test. I think a good case can be made for considering this a false assumption. The second is the assumptions that mere word use is how we define not only intelligence, but language. Both of these are demonstrably false. If the assumptions the test is built on are false, then we need to rethink what the test is measuring, and whether we still feel this is a sufficient measure of intelligence.

Turing Judges.

The idea of the Turing Test is that a person sits at a teletype machine that prints texts and allows the operator to type text. The human and the test subject sit in different rooms and use the teletype machines to communicate. A machine can be said to pass the Turing Test if a human operator of the teletype cannot tell that the subject is not human. This puts word use at the forefront of Turing's definition of what it means to be intelligent. 

Human beings use of language is indeed one of our defining features. Animals use faculties that hint at a proto-language facility. No animal uses language in the sense that we do. At best animals show one or two of the target properties that define language. They might for example have several grunts that indicate objects (often types of predator), but no syntax or grammar. There has been significant interest in programs that sought to teach apes to use language either as symbols or gestures. But most of this research has been discredited. Koko the gorilla was supposedly one of the most sophisticated language uses, but her "language" in fact consisted of rapidly cycling through the repertoire of signs, with the handler picking the signs that made most sense to them. In other experiments subtle cues from handlers told the animals what signs to use. More rigorous experiments show that chimps can understand some language, particularly nouns, but then so can grey parrots, some dogs, and other animals. Crucially they don't use language to communicate. In fact a far more impressive demonstration of intelligence is the ability of crows to improvise tools to retrieve food, or the coordinated pack hunting of aquatic mammals like orca and dolphins. So animals do not use language, but are none the less intelligent. 

Humans are all at different levels when it comes to language use. Some of us are extraordinarily gifted with language and others struggle with the basics. The distinctions are magnified when we restrict language to just written words. This restriction alone is doubtful. Language as written language, even if used for a dialogue, is only small part of what language use consists of. A great deal of what we communicate in language is conveyed by tone of voice, facial expression, hand gestures, or body posture. Those people who can use written language well are rare. So a Turing judge is not simply distinguishing a machine from a human, but is placing a machine on a scale that includes novelists and football hooligans. What happens when the subject responds to any question by chanting "Oi, oi, oi, Come on you reds!"? Intelligence, particularly as measured by word use, is not a simple proposition. 

The Turing Test using text alone would be more interesting if we could define in advance what elements would convince us that the generator of the text was human. To the best of my knowledge this has never been achieved. We don't know what criteria constitute a valid or successful test. We just assume that any generic human being is a good judge. There's no reason to believe that this is true. As I've mentioned many times now, individuals are actually quite poor at solo reasoning tasks (See An Argumentative Theory of Reason). Reason does not work the way they we thought it did. Mercier & Sperber have argued that at least one of the many fallacies that we almost inevitably fall prey to—confirmation bias—is a feature of reason, rather than a bug. M&S argue that this is because reason evolved to help small groups make decisions and those who make proposals think and argue differently to those who critique them. On this account, any given individual would most likely be a poor Turing judge. 

Humans beings evolved to use language. Almost without exception, we all use it without giving it much thought. Certain disorders or diseases may prevent language use, but these stand out against the background of general language use: from the Amazon jungles to the African veldt, humans speak. The likelihood is that we've been using language for tens of thousands of years (See When Did Language Evolve?). But writing is another story. Writing is unusual amongst the world's languages, in that only a minority of living languages are written, or were before contact with Europe. Writing was absent from the Americas, from the Pacific, from Australia and New Guinea. The last two have hundreds of languages each. Unlike speaking, writing is something that we learn with difficulty. No child spontaneously begins to communicate in writing. Writing co-opts skills evolved for other purposes. And as a consequence our ability to use writing to express ourselves is extremely variable. Most people are not very good at it. Those who are, are usually celebrated as extraordinary individuals. Writers and their oeuvre are very important in literary cultures.

So to chose writing as the medium of a test for intelligence is an extremely doubtful choice. We don't expect intelligent human beings to be good at writing. Many highly intelligent people are lousy writers. We don't even expect people who are gifted speakers to be good at writing, which is why politicians do not write their own speeches! Writing is not a representative skill. Indeed it masks our inherent verbal skill.

In fact it might be better to use another skill altogether, i.e. tool making. A crow can modify found objects (specifically bending wire into a hook) to retrieve food items. Another important manifestation of intelligence is the ability to work in groups. Some orca, for example, coordinate their movements to create a bow-wave that can knock a seal off an ice-flow. This is a feat that involves considerable ability at abstract thought, and they pass this acquired knowledge onto to their offspring. The ability to fashion a tool or coordinate actions to achieve a goal are at least as interesting as manifestations of intelligence as language is.

Language and Recognition.

My landlady talks to her cats as though they understand her. She has one-sided conversations with them. Explains to them narratively when their behaviour causes her discomfort, as though they might understand and desist (they never do). She's not peculiar in this. Many people feel their pets are intelligent and can understand them even if they cannot speak. Why is this? Well, at least in part, it's because we recognise certain elements of posture in animals corresponding to emotions. The basic emotions are not so different in our pets that we cannot accurately understand their disposition: happy, content, excited, tired, frightened, angry, desire. With a little study we can even pick up nuances. A dog that barks with ears pinned back is saying something different to one that has its ears forward. A wagging tail or a purr can be a different signal depending on circumstances. A lot of it has to do with displays of and reception of affection. 

Intelligence is not simply about words or language. Depending on our expectations the ability to follow instructions (dogs) or the ability to ignore instructions (cats) can be judged intelligent. The phrase emotional intelligence is now something of a cliché, but it tells us something very important about what intelligence is. A dog that responds to facial expressions, to posture and tone of voice is displaying intelligence of the kind that has a great deal of value to us. Some people value relationships with animals precisely because the communication is stuck at this level. A dog does not try to deceive or communicate in confusingly abstract terms. An animal broadcasts its own disposition ("emotions") without filtering and it responds directly to human dispositions. Many people would say that this type of relationship is more honest.

There's a terrible, but morbidly fascinating, neurological condition called Capgras Syndrome. In this condition a person can recognise the physical features of humans, but their ability to connect those features with emotions is compromised. Usually when one sees a familiar face there is an accompanying emotion that tells us what our relationship with the person is. If we feel disgust or anger on recognition, then we know them to be enemies, perhaps dangerous and we act to avoid or perhaps confront them. If the emotion is joy or love then we know it's a friend or loved one. In Capgras the emotional resonance is absent. With loved ones the absence of that emotion is so strange that the most plausible explanation often seems to be that these are mere replicas of loved ones, or lookalikes. The lack of emotion in response to a known face can be incapacitating in the sense of disrupting every existing relationship. In the classic novel, The Echo Maker, by Richard Powers, the man with Capgras is able to recognise and respond to his sister's voice on the telephone, but does not feel anything when he sees her. The same is true for his home and even his dog. The only way he can explain it is that they are all substitutes cleverly recreated to fool him. Only he isn't "fooled" which creates a nightmarish situation for him. 

The problem, then, with the Turing Test is that it is rooted in the old Victorian conceit about reason being our highest faculty. Reason was, until quite recently, considered to float above the mere bodily processes of emotion. In other words it was very much caught up in Cartesian mind/body dualism and the metaphors associated with matter and spirit (See Metaphors and Materialism). Reason is associated, by default, with spirit, since it seems to be distinct from emotion. We now know that nothing could be further from the truth. Cut off from emotions our minds cannot function properly. We cannot make decisions, cannot assess information, and cannot take responsibility for our actions. The Turing test assumes that intelligence is an abstract quality, separable from the body. But these assumptions are demonstrably false.

What Kind of Intelligence?

I've already pointed out that language is more than words. I've expanded the idea of language to include the prosody, gesture and posture associated with the words (which as we know shapes the meaning of the words). An ironic eyebrow lift can make words mean something quite different than their face value. The ability to use and detect irony depends on non-verbal cues. This is why, for example, irony seldom works on Twitter. Text tends to be taken on face value, and attempts at irony simply cause misunderstanding. This is true in all text based media. In the absence of emotional cues we are forced to try to interpolate the disposition of the interlocutor. Getting a computer to work with irony would be an interesting test of intelligence!

Indeed trying to assess the internal disposition of the hidden interlocutor is a key aspect of the Turing Test. Faced with a Turing Test subject I suspect that most of us would ask questions designed to evoke emotional responses. This is because we intuit that what makes us human is not the words we use, but the feelings we communicate. Someone who acts without remorse is routinely referred to as "inhuman". In most cases humans are not good at making empathetic connections using text - which is why text-based online forums seem to be populated with borderline, if not outright, sociopaths. It's the medium, not the message. Personally I find that doing a lot of online communication produces a profound sense of alienation and brings out my underlying psycho-pathology. Writing an essay however is far more productive exercise than trying to dialogue in text. Even the telephone, with it's limited frequency range, is better for communicating, because tone of voice and inflection communicates sufficient to establish an empathetic connection. 

So if a computer can play chess better than a human being (albeit with considerable help from a team of programmers) then that is impressive, but not intelligent. The computer plays well because it does not feel anything, does not have to respond to its environment (internal or external), and does not have any sense of having won or lost. It has nothing for us to relate to. Similarly, even if a computer ever managed to use language with any kind of facility, i.e. if it could form grammatically and idiomatically correct sentences, it would probably still seem inhuman because it would not share our concerns and values. It would not empathise with us, nor us with it. 

I suppose that in the long run a computer might be able to simulate both language and an interest in our values so that in text form it might fool a human being. But would this constitute intelligence? I think not. A friendly dog would be more intelligent by far. Which is not to say that such a computer would not be a powerful tool. But we'd be better off using it to predict the weather or model a genome than trying to simulate what any of us, or any dog, can do effortlessly.

An argument against this point of view is that our minds are tuned to over-estimate intelligence or emotions in objects we see. So we see faces in clouds and agency in inanimate objects. So an approximation of intelligence would not have to be all that sophisticated to stimulate the emotions in us that would make us judge it intelligent. For example, in movies robots are often given a minimal ability to emote in order to make them sympathetic characters. The robot, Number five, in the film Short Circuit has "eyebrows" and an emotionally expressive voice and this is enough for us to empathise with it. So perhaps we will be easily fooled into believing in machine intelligence. But this means that simulation of intelligence is insufficiently impressive because people are easily fooled.

This point is brilliantly made in the movie Blade Runner. The Voight-Kampff test is designed to distinguish "replicants" from humans based on subtle differences in emotional responses. The replicants are otherwise indistinguishable from humans. The test of Rachael is particularly difficult because she has been raised to believe she is human (the logic of the movie breaks down to some extent because we do not learn by Deckard persists in asking 100 questions if Rachael is answering satisfactorily). Ridley Scott has muddied the waters further by suggesting that the blade runner, Deckard, is himself a replicant, though based on the original story and the context of the film this seems an unlikely twist.

So there are two major problems here: what makes a good Turing test; and who makes a good Turing judge. The whole set up seems under-defined and poorly thought out at present. My impression is that passing the Turing test as it is usually specified is a trivial matter that would tell us nothing about artificial intelligence or humanity that we do not already know. 

Conclusion

It seems to me that we have many reasons to rethink the Turing Test. It seems to be rooted in a series of assumptions that are untenable in light of contemporary knowledge. As a test for intelligence the Turing Test no longer seems reasonable. On one hand the way that it defines intelligence is far too limited. The definition of intelligence it uses is rooted in Cartesian Dualism which sees intelligence as an abstract quality, not rooted in physicality, not embodied. And this is simply false. Emotions, as felt in the body, for example, play a key role in how we process information and make decisions.

As much as anything our decision on whether or not an entity is intelligent or not, will be based on how we feel about it, how interacting with it feels to us. We will compare the feeling of interacting with the unknown entity, to how it feels to interact with an intelligent being. And until it feels right we will not judge that entity intelligent.

In Turing's day we simply did not understand how decision making worked. We still thought of abstract reasoning as a detachable mental function unrelated to being embodied. We still saw reason as the antithesis of emotion. Now we know that emotion is an indivisible part of the process. We must now consider that reason itself may not have evolved for seeking truth, but merely for optimising decision making in small groups. At the very least, the lone teletype operator needs to be replaced with a group of people; and mere words must be replaced by tasks that involve creativity and cooperation. A machine ought to show the ability to cooperate with a human being to achieve a shared goal before being judged "intelligent". The idea that we can judge intelligence at arms length, rationally, dispassionately has little interest or value any more. We judge intelligence through interaction, physical interaction as much as anything.

As George Lakoff and his colleagues have shown, abstract thought is rooted in metaphors deriving from how we physically interact with the world. Our intelligence is embodied and the idea of disembodied intelligence is no longer tenable. As interesting as the idea may appear, there is no ghost in the machine that can be extracted or instantiated and maintained apart from the body. Any attempts to create disembodied intelligence will only result in a simulacrum, not in intelligence that we can recognise as such.

Buddhists will often smugly claim this as their own insight, though most Buddhists I know are crypto-dualists (most believe in life after death and karma for example). I've argued at length that the Buddha's insight was into the nature of experience and that he avoided drawing ontological conclusions. Thus, although we read the texts as being a critique of doctrines involving souls, the methods of Buddhism were always different from the methods of Brahmanism. The Brahmins sought to experience the ātman as a reality, and from the Upaniṣadic description ātman could be experienced as a sense of oneness or connection with everything in the world (oceanic boundary loss). Buddhists deconstructed experience itself to show that nothing in experience persisted and that therefore, even if there was a soul we must either always experience it, or it could never be experienced, and since we start off not experiencing it, no permanent soul can ever be experienced (which is not a comment on whether or not such a soul exists!). Therefore the experiences of the Brahmins are of something other than ātman. Only after Buddhists had started down the road of misguided ontological speculation did this become an opinion about the existence of a soul. So the superficial similarities between ancient Buddhist and modern scientific views is an accident of a philosophical wrong turn on the part of Buddhists. They got it partly right by accident, which is not really worth being smug over.

History shows that we must proceed with real caution here. Our Western views on intelligence have been subject to extreme bias in the past and this has led to some horrific consequences for those people who failed our tests for completely bogus reasons. We must constantly subject our views on intelligence to the most rigorous criticism and scepticism we are capable of. Our mistakes in this field ought to haunt us and make us extremely uncomfortable. This is yet another reason why tests for intelligence ought to require more interactivity. If we do create intelligence we need to know we can get along with it, and it with us. And we know that we have a poor record on this score.

The Turing Test seems not to have been updated to take account of what we know about ourselves nowadays. The test itself is anachronistic. The method is faulty, because it is based on a faulty understanding of intelligence and decision making. We are not even asking the correct question about intelligence. With all due respect to Alan Turing, he was a man of his time, a glorious pioneer, but we're moved on since he came up with this idea and it's had its day. 

~~oOo~~

See also: Why Artificial Intelligences Will Never Be Like Us and Aliens Will Be Just Like Us. (27 June 2014)

Yāmagaṇḍika: Telling the Time in Ancient India

Revision 2.0 - 3 May 2015

My Pāḷi reading group has been working through the commentary to the Kāraṇiya Metta Sutta which I translated for this blog some years ago (11 Jun 2010). In this text we come across an unusual term that has no counterpart in the suttas. In picturing some bhikkhus zealously meditating in the forest it describes them as yāmagaṇḍikaṃ koṭṭetvā. This is a curious expression and in this essay I'll attempt to elucidate what it means. The compound yāmagaṇḍika occurs only twice, both times in commentarial texts (Paramatthajotikā SnA 1.193; Papañcasūdaniyā, MNA 1.122) and these should be enough to allow us to gain some clarity. We'll see that the commentator does not see his own time in context, but wrongly assumes that his milieu reflects that of the Buddha some centuries earlier. 

The gerund koṭṭetvā must come from the verb koṭṭeti (from a rare root √kuṭ or kuṭṭ) 'to beat, crush, pound'. For example it is the action associated with a mortar (udukkhale koṭṭetvā DN ii.341) and with pounding grain (dhaññaṃ koṭṭenti Thī  117). It has other minor senses in PED, but these don't seem relevant here. The compound yāmagaṇḍika combines yāma and gaṇḍikā. We'll take these one at a time. 

According to PED gaṇḍikā derives from gaṇḍa 'a swelling; a stalk or shaft' + -ikā. The formation gaṇḍikā means 'a stalk or shaft', particularly 'the trunk of a tree' and by association 'a block of wood'. However there is a potential confusion here with ghaṇṭā 'bell' or ghaṭikā 'gong'. As we will see the CST edition of the text is quite unreliable and this means we must allow for errors. In the Digital Pāḷi Reader version of this text, we find yāmaghaṇḍikaṃ koṭṭetvā. The spelling -ghaṇḍikaṃ occurs in the Majjhima Ṭīkā  (the sub-commentary on MNA 1.121) "yāmaghaṇṭikaṃ paharati"  (MNṬ 1.196) though the Aṭṭhakāthā has -ga-. The Khuddaka Nikāya Commentary—which parallels the Suttanipata commentary—also has -gh-.

Pañjaranatha Mahākāla
with gaṇḍikā

DOP sv ghaṇṭī/ghaṇḍī, suggests a confusion with gaṇḍi and ghaṇṭā. If it does mean 'block' then it must refer to a resonant gong-like block that is 'pounded' (√koṭṭ) as a time signal. Buddhadatta's Concise Pali-English Dictionary defines gaṇḍikā as "(f.) a hollowed block of wood which is used to serve the purpose of a bell; a gong." A gaṇḍī or gaṇḍikā is the characteristic implement of a form of Mahākāla known as Pañjaranatha. In the image on the right he holds it across his body (thanks to Maitiu for pointing this out).

Yāma is complicated because it has homonyms that derive from different verbs. From √yam 'hold, hold back' + -a we get yāma 'restraint'; and from √yā 'go' + -ma we get yāma 'motion, going, progress'. The latter is used figurative to mean 'a watch of the night'. We frequently read in Pāḷi of the three watches of the night (tiyāmā): paṭhamayāma, majjhimayāma, and pacchimayāma (first, middle, and last watches). The practice of dividing the night in particular in watches was common in the ancient world. The Latin name for these periods was vigilia, whence English 'vigil'. Incidentally yāma can also be a collective noun for people or things related to the God of the afterlife, Yama, in this case his name means 'twin', from √yam 'combine'.

The compound, yāmagaṇḍika, can really only be a tatpuruṣa so it must mean something like 'the block of restraint', or 'the gong of the watches'. The context is that the monks are resolute night and day, devoted to wise attention, and sitting at the foot of trees meditating. It may be that 'beating the block of restraint' is a metaphor that we no longer understand, similar to the Buddha saying to Upaka the Ājīvaka in the Ariyapariyesana Sutta, āhañchaṃ amatadundubhiṃ 'I beat the drum of the deathless' (MN i.171). It's not entirely obvious what this means since drums are primarily for entertainment in our society.

However, I believe that here we must read yāma as 'watch of the night' and the phrase means 'beating the block or pounding the gong that marks the watches'. For confirmation we can look at the second of the two occurrences of yāmagaṇḍika at MNA 1.122 (already mentioned above):

Ajagaravihārepi kāḷadevatthero antovasse yāmagaṇḍikaṃ paharati, āciṇṇametaṃ therassa. Na ca yāmayantanāḷikaṃ payojeti, aññe bhikkhū payojenti. Atha nikkhante paṭhame yāme there muggaraṃ gahetvā ṭhitamatteyeva ekaṃ dve vāre paharanteyeva vā yāmayantaṃ patati,

We immediately strike a problem in that ajagara probably means 'python' or some other large snake and doesn't fit the context, and the spelling of the next word (with -tth-) is suspect. Consulting the Dictionary of Pāli Names we find an entry for a Thera named Kāḷadeva:

"...incumbent of Vajagaragiri-vihāra. He is mentioned as having known the exact passage of time without the help of an "hour-glass" (yāmayantanālika). MA.i.100f

This is in fact, a reference to the passage we are about to analyse. It's thus apparent that the CST (Burmese) edition is incorrect here and we must amend it to:

Vajagara[giri]vihārepi kāḷadevathero antovasse yāmagaṇḍikaṃ paharati, āciṇṇametaṃ therassa. Na ca yāmayantanāḷikaṃ payojeti, aññe bhikkhū payojenti. Atha nikkhante paṭhame yāme there muggaraṃ gahetvā ṭhitamatte yeva ekaṃ dve vāre paharante yeva ca* yāmayantaṃ patati. 

The Elder Kāḷadeva of Vajagaragiri Monastery, performs this striking of the block of the watches till the end of the rains. And he does not use a measuring device as other monks did. At the end of the first watch the Elder takes up the hammer (muggara) and strikes twice for every measure of time, just as the watch-mechanism falls. 

* The text has vā, but I think this must also be wrong, and have amended to ca. 

My translation of this passage is a little rough, but the main points are clear. For our purposes two things are important. It is entirely clear that yāma must refer to 'a watch of the night' rather than 'restraint'. Secondly we read that Kāḷadeva did not yāmayantanāḷikaṃ payojeti, that he used a hammer (muggara) to strike the block, and then yāmayantaṃ patati. And this helps to fill out what the author of the Metta Sutta commentary was thinking.

One of the problems of living a regular life is keeping time. The early forest monks had no way of telling the time apart from the sun, moon and stars. Pāḷi distinguishes day (diva) from night (ratti) and we read of monks doing things in the morning-time (pubbaṇhasamaya) or evening-time (sāyaṇhasamaya). We know that the phases of the moon—full moon (puṇṇacanda) and new moon (navacanda)—were important for organising the lives of monks. The moon takes on a magical significance for some Buddhists as a result of this. The watches of the night, however, are far more difficult to determine. How did monks, living in a forest, know when the watches began and end. Presumably the first watch started at dusk and the last ended at dawn, but what marked the other boundaries? Presumably one versed in astronomy would be able to keep track of when certain stars were due to rise and set, but the three month retreat is during the rain season when the skies are perpetually cloudy. 

The simple answer is that the first monks almost certainly did not keep accurate track of the time and that the watches were assessed subjectively. And we can point out that no references to time keeping apart from observing the sun and moon are referenced in the suttas. The texts we are dealing with here, however, are from 5th century Sri Lanka and from an environment of highly organised, large scale, urban monasteries.

If we now look at the phrase yāmayantanāḷikaṃ payojeti we can see that the DOPN glosses it is as "the help of an hour-glass". Now an hour-glass is anachronistic here, they did not exist in this time or place. But yanta does mean 'mechanism' and nāḷika 'a tube or measure'. So we know that Kāḷideva did not, as other monks did, employ (pa√yuj) a measure/tube device for the watches (yāma-yanta-nāḷika). This suggests some kind of clock, but is the idea plausible? I had a dig around in some horological books and apparently it is plausible to think that in first millennium India there were water-clocks.

Water-clocks come in two forms: a vessel with a hole that allows water to leak out slowly, and the slight more sophisticated sinking bowl, in which a bowl with a hole in it gradually sinks into a container of water. The books suggest that the sinking-bowl water-clock was common in India by medieval times and so accurate that it probably delayed the introduction of mechanical clocks. Importantly the attendant of water-clock announced the end of the time period by striking a 'gong'.  The Gujarati word  for which was ghaḍiyār. There's an outside possibility that this word is related to gaṇḍikā or ghaṭika.

Persian Water Clock.

We do know that the Achaemenid Persians possessed just such water clocks, from the records of Alexander's conquests in India by Callisthenes of Olynthus. We know that similar water-clocks were employed to mark the passage of time in monasteries in North India by the 7th century. This information comes from the records of Yijing (義淨 aka I-Tsing; ) a Chinese monk who lived 635–713 CE, and spend 25 years travelling, taking the southern sea route to India. Yijing's account (see translation by Takakusu 1896: 142-6) is widely recycled in a variety of other sources, for example Misra (1998) simply quotes Takakusu at length, while Sharfe (2002) paraphrases and the Wikipedia article on water-clocks cites Sharfe. Yijing records the use of sinking bowl water clocks in several monasteries, with each using slightly different measures and signalling conventions. The bowls were made of copper and were very expensive, generally being the gift of a king to a monastery. Such clocks were also used by the ancient Britons. 

Sri Lankan
water-clock bowl
McGill. 

So it seems at least plausible that urban monks in fifth century Sri Lanka measured the hours of the day using a water-clock and marked the increments by striking some kind of gong (probably wooden given how expensive metal was). And what our commentators have done is imagine that this is also what monks did in the Buddha's time. Thus when they tell the story of the Metta Sutta they project this technology backwards. And we know that they have done in this other ways as well. For example they projected South Indian kinship patterns familiar, to them in Sri Lanka, onto the family tree of the Buddha and his family, even though these patterns were out of place in North India (See Attwood 2012). But it is extremely unlikely that forest monks in the fifth century BC uses anything so elaborate to measure time.

One little loose end is that having struck the gong with the hammer, yeva ca yāmayantaṃ patati. Now, patati comes from √pat 'fall, fly' and it's not usually a transitive verb. Yanta being a neuter noun we can read this as 'and just as the watch-mechanism falls'. If the yāmayanta falls at the end of the time period, then this is consistent with a sinking bowl style water clock.

It is fascinating how a short phrase like this one can open a window into history. And while here we are not talking about the time of the Buddha, but of the period of the Sri Lankan commentators, it is still a glimpse of history. It reinforces the point that the commentaries reflect their own time rather than any earlier time. They are apt to project their own culture and technology backwards onto the past, making them unreliable guides to the past. Thus when we consult the Pāḷi commentaries for insights into the suttas we must be cautious in drawing historical conclusions. The commentators were no doubt sincere, but they had a vested interest in trying to establish that the past was reflected in the present because it was one way of establishing their legitimacy as bearers of the tradition. It shows how very tenuous lineage is as a guide to legitimacy or authenticity. 

~~oOo~~

Bibliography

Attwood, Jayarava. (2012) 'Possible Iranian Origins for Sākyas and Aspects of Buddhism.' Journal of the Oxford Centre for Buddhist Studies, 3.

Misra B.N. (1998) Nālandā: Vol. 1. Sources and Background. B.R. Publishing Corporation.

Sharfe, Harmut. (2002) Education in Ancient India. Brill 2002. 

Takakusu, J. trans. (1896) I-Tsing, A Record of the Buddhist Religion : As Practised in India and the Malay Archipelago (A.D. 671-695), Clarendon Press 1896. Reprint. New Delhi, AES, 2005.