These days the name of Alan Turing is associated as much with computers as the name Isaac Newton is with gravity. Quite rightly so. Whilst his work on cryptanalysis at Bletchley Park during World War Two might cause some to consider him a shadowy figure in the world of twentieth century espionage, I would like to think that in the long historical view it will be a thought experiment of his that will be remembered most of all - the Turing Test.

In its simplest form the test states that if an interrogator having a conversation over a keyboard (online chat, basically) with a second party cannot distinguish between a real person and a computer program, then the computer (program) could be said to be thinking.

Even though this once thought experiment has now been carried out in reality, (most notably at the Loebner Prize which has been carried out annually since 1991) no-one yet wants to stick their neck out and claim that a machine has definitely passed and ipso facto can think.

This is partly because, despite the prodigious speed at which computer technology has progressed over the past twenty years, this progression has been in completely unexpected directions. No-one really predicted the extent and functionality of the World Wide Web and yet in on 12 January 1992 we were not even remotely close to HAL becoming operational at the HAL Laboratories in Urbana, Illinois. Now, ten years after the date of the ill fated Discovery mission, HAL still seems a very long way away.

It’s also because Artificial Intelligence seems to be a moving target. Whilst we are still a long way from HAL, you do get the impression that even if intelligent talking computers were constructed, there would be those who would continue to insist that they weren’t “really” thinking, that they were only mimicking human intelligence. There has even been a pre-emptive attempt to debunk the Turing Test.

Like the Turing Test was originally, it's a thought experiment. It is known as the Chinese Room and was devised by philosopher John Searle.

The Chinese Room is a large wooden box in which sits an Experimenter. On his or her desk there is a set of complex instructions – whether these are in the form of data on a computer’s hard disk or a series of handsome leather bound volumes is entirely irrelevant. The Experimenter also has access to a large number of sheets of paper and several pencils.

There is a slot in one wall of the room. Through this slot people post questions in Chinese. The Experimenter doesn’t understand Chinese – but this doesn’t matter. Without needing a translation, he or she can look up the Chinese characters in the data, and by following a long series of steps listed in the instructions, eventually come up with and write down an answer to the question, also in Chinese characters, and post it back through the slot.

However long this might take (which doesn’t matter as it’s a thought experiment), the interrogator on the outside has now received an intelligible answer. If this went on long enough, it would be possible for the Chinese Room to pass the Turing Test.

But, crows the Experimenter, I don’t speak a word of Chinese!

The room has passed the Turing Test but the Experimenter wasn’t thinking about the questions - he or she didn’t even hear them.  The Experimenter was able to simulate their half of an intelligent conversation without actually understanding it at all. This proves that machines can’t actually think, whatever the Turing Test might claim.

Or does it?

I would say not. All that the Chinese Room experiment proves is that the Experimenter can follow instructions without understanding Chinese. And just because he or she doesn't understand Chinese, it doesn't mean that an understanding of Chinese isn't going on somewhere...

The notion of the Chinese Room disproving the possibility of artificial intelligence is a demonstration of Cartesian Theatre thinking. By saying that the Experimenter doesn't understand Chinese ergo no understanding of Chinese is going on, the Experimenter is being cast in the role of the homunculus, the soul - the room itself and the instructions themselves being relegated to mere machinery.

In fact the opposite may well be true.

The Experimenter is no more than part of the machine - why should he or she understand Chinese any more than the plywood making up the box's exterior or the pencils with which he uses to draw the Chinese Characters do? Consciousness and understanding is something that arises from a whole system and whilst our Experimenter doesn't understand Chinese him or her self, the system as a whole most demonstrably does understand Chinese. And certainly a knowledge of Chinese would have been required when the instructions were written – when the Chinese Room learned.

Of course it would be nonsense to describe the Chinese Room being discussed here as conscious seeing as all the instructions do is allow responses to be produced very slowly and all it can do is conduct simple conversations in Chinese. It has no inner life and as such I assume would always answer the same question in the same way.  Similarly whilst Deep Blue may be a chess champion it had none of the other qualities that made Garry Kasparov a conscious being. However, this is simply a question of scale. A large enough Chinese room (or perhaps a city-sized building consisting of millions of Chinese rooms each with a different purpose) with myriad operators could well be conscious and self aware when viewed as a whole even though this would be on a far different scale from that we are used to.

However, scales of time and space are irrelevant when it comes to the discussion of intelligence and consciousness - as we demonstrated in The Experiment of Thugg 2.0 back in September 2010. All that matters is that the data is processed and the inclusion of an Experimenter who doesn't understand Chinese in the equation is irrelevant and humano-centric. Your eyes don't speak English and yet you are reading and understanding this. A Chinese room would probably be far more efficient with a computer and a printer attached to the input and output and yet would produce exactly the same results as the inclusion of an Experimenter.

The Chinese Room appears to be a remnant of dualistic thinking. By denying the right of machines to be conscious the proponents of such theories are surreptitiously positing the existence of a separate soul as the seat of understanding and consciousness.

I thought we’d got past that.

It is surprising how seriously some people take fiction sometimes.

The word canon originally meant the books of the Bible that were official and contained the true scriptures as laid down by the various churches and faiths who concerned themselves with such things. It has since been sequestered by the enthusiasts of various fictional worlds to mean the events and stories that officially "happened" in that universe.

When a fictional world or universe is created often additional spin off fiction is produced - initially to capitalise on any possible popularity of the franchise and turn a tidy buck. Some early examples of such works were the Star Wars novels Splinter of the Minds Eye and Han Solo at Stars End which were churned out shortly after the success of the original Star Wars film (the one that is now rather dully referred to as A New Hope).

Despite claims on the covers that these novels were "from the adventures of Luke Skywalker" they really didn't seem to have much to do with the series of films that followed, having been written as quick cash ins before it had been realised just how phenomenally successful the franchise would become. They never really became incorporated into the wider story (which is a shame as the Han Solo novel contained a droid called Bollux).

Looking into what consists Star Wars canon now, it all seems insanely complicated. However it is a naught compared to the baroque complexities of Star Trek canon which has to incorporate five live action TV series, an animated series, eleven movies to date and numerous novels and comics. Despite the Sisiphean magnitude of this task there do seem to have been attempts by the makers to provide in universe explanations for inconsistencies between the earlier and later iterations of the narrative.

Personally I don't think it really matters, a story is a story is a story and I can enjoy a well written novel featuring Kirk, Spock and McCoy far more than a poor TV episode, despite the fact that the latter would be considered more canonical by the powers that be (i.e. the fans).

However, if you really want to see deep debate about canon and what happened or didn't, then you need look no further than Doctor Who fandom. During the show's original run the only books produced were novelisations of the TV stories and where these contradicted one's memories of the episodes themselves I tended to imagine that the events in the novels were what would have been filmed in the absence of time and budget restraints. The Target novelisations had the limitless budget of the reader's mind's eye, splintered or not.

The only stories outside regular continuity were those in the comics, and personally I didn't lose any sleep wondering when Jon Pertwee's Doctor managed to fit in the solo travels during which the TARDIS was swallowed by a living planet into the adventures he had on screen with Jo and Sarah-Jane. It was just another story to enjoy.

But then the TV series was cancelled in 1989 and it all got very complicated...

First out of the traps was the series of "official" novels, the New Adventures, which continued the story where the TV series had left off. At the time I fully intended to start buying these and following the story but it soon became overwhelming. When they started publishing Missing Adventures as well it was all too much and I decided not to bother. Whilst I would occasionally buy a book when I needed something to read, I didn't feel the need to collect them all. It was too complicated and I had to give up hope of following everything that might have happened to The Doctor.

After all, they were only stories. Fiction. No more or less real than what I might imagine in my head.

The appearance of the TV movie in 1996 stirred things up a bit and gave the books a kick but it wasn't until 1999 that an entire new level of complexity was added to the equation. Original Doctor Who audio plays started being produced by a company called Big Finish starring the original actors. These felt far more like real Doctor Who than the books, especially at a time when it seemed unlikely ever to return to our screens...

How wrong we were. In 2005 the Doctor was back on TV and furthermore the audio plays continued to be produced. Some of them were even broadcast on BBC radio.

Generally I just thought this was a good thing. More stories. More fiction. More Doctor. But some people got very upset by inconsistencies in the narrative that had arisen as a natural consequence of allegedly adjacent adventures being written and recorded decades apart.

Some simply refused to accept the audio adventures as canon. Others tied themselves in intellectual knots trying to explain away these continuity errors - I recall a long thread on a forum wondering why, when he was dying at the climax of the 1984 TV adventure The Caves of Androzani, the Doctor only had visions of the companions he'd had during the past three years on TV and not of Erimem the Ancient Egyptian princess who traveled with him and Peri during Big Finish audio adventures which supposedly took place between the previous story (Peri's debut, Planet of Fire) and this one.

This seemed to me to be a non-question. A no brainer. Erimem's first audio story, Eye of the Scorpion, was recorded in 2001, some 17 years after Caves of Androzani had been televised. Of course the Doctor wouldn't remember her, and no amount of mental sleight-of-hand would produce a satisfactory in-universe explanation for why he didn't. Nor should it. It was a story and no matter how good a story there was no way it could incorporate elements of another story written seventeen years later.

But this kind of thing seemed to really upset some people. Seriously. If you think about the original purpose of story and narration, it becomes clear as to why this might be.

We are the only animals (that we know) that tell stories. We narrate, and some might claim that it is this ability itself that gives rise to our consciousnesses, our selves. In order to remain sane and maintain a coherent sense of self it is important that these stories make sense, that they are consistent. It's no good remembering that you went to school in Golders Green in 1982 if another memory claims that was part of the five years you spent living in Australia. By definition reality has to be consistent; it's one of the ways we can tell the difference between it and dreams.

And may be the reason why canon-fans get so upset about continuity errors in their favourite fictional universe.

More than anything else they want the Doctor to be real.

They want it all to make sense because in some way it all actually happened. They still live in hope that one day they will walk around the corner and see a tall blue Police Box standing where there was only empty space five minutes before, ready to whisk them away from this dull consistent world into an exciting, but nonetheless still consistent, universe.

I know how they feel. I used to feel that too. But I never felt that it all had to fit together. If I wanted to be scientific about it Many Worlds Theory and parallel universes could take care of any inconstancies. But even forgetting all that there was no reason why a real person couldn't have imaginary stories told about them.

Just because I wrote a short story when I was at primary school about how I went to Narnia it doesn't mean that I don't exist.

Does it?

These days there is no excuse for not knowing the answer to trivial questions. The answer is always on the end of a google and we now have google at our fingertips most of the time.

However, it is sometimes more fun not to know something. I have no idea what the Elgin Marbles actually are and I prefer it that way. I know that they're in the British Museum, I know that people think that the UK should return them to Greece, but I have absolutely no desire to type the phrase "Elgin Marbles" into a search engine and dispose of my ignorance.

This is because what I imagine they might be is more fun.

When I was a kid I had one of those furry pencil cases; mine was orange and I didn't use it to keep pencils in. Oh no, I used it for my collection of marbles.  I was obsessed with marbles. In retrospect it was a short lived obsession, but it seemed all consuming at the time.  It was symptomatic of the wider craze sweeping the school; in the playground in between lessons all you could hear was talk of Oners, Tenners, Chinas, Clears and other nomenclatures which now escape me. The strange thing was that we rarely seemed to actually play the game of marbles itself.  We just collected them, in the same way as we collected other things like miniature plastic heads of the England World Cup Squad (despite a total lack of interest in football), sets of fake coins or Star Wars bubblegum cards.

There were even some myths and legends associated with marble collecting.  I remember very well the tale of the mythical Tenner Clear. A Clear was a marble that was plain glass; not that exciting in itself. A Tenner was a marble allegedly ten times the size of a normal one. They did exist; in reality they were only three times the diameter of a normal Oner, rather than ten although they would have had nearly ten times the volume.

I had never seen a Tenner Clear and in my head it took on marvellous properties, like a crystal ball in which you could see your future, an amulet that would bestow upon the owner the power to collect all the marbles he or she could have ever desired.

Whispers started circulating that there was a Tenner Clear under the Prefab.

The Prefab was a giant Portakabin which housed the reception classes and had been erected at one end of the playground, probably in the 1950s or 60s. It was raised from ground level on supports underneath which, perhaps unwisely, there was just enough room for a child to crawl. No one ever did of course, we were all too scared.

But then the rumours arose.  There was a Tenner Clear under the Prefab.  It was only visible from the side of the Prefab that faced away from the main school building. We all got down on our bellies and peered beneath, yes, there it was, we were sure of it.  Amongst the broken glass, fragments of brick, rusty tins, moss and spiders there was quite plainly something circular and tantalisingly marble-like reflecting the light back at us. It was dark but we were sure of it.

Which one of us would be brave enough to crawl under there and claim their prize?

Several playtimes came and went, most of which were spent lying flat on the concrete staring at the Tenner Clear. Then one boy braver than most took it upon himself to crawl under there in a bid to make the Tenner Clear his own. I remember watching as he disappeared from the daylight and made his way slowly across to where the treasure was. However, he turned round and started heading back towards the light far too early. When he emerged he said that there was no Tenner Clear - it was just the bottom of a Coke can reflecting the light back at us. He stood up and we all gasped - thick dark red blood was oozing from a wound on his knee. In the darkness he'd crawled over some broken glass.

In response to this accident, the school authorities sealed off the underside of the Prefab with stout chicken wire. I was convinced that the Tenner Clear was still under there, now unreachable, even though a first hand report had said it didn't exist. Lying on my stomach in the dust I peered through the chicken wire and persuaded myself that I could still see it. It didn't look like the bottom of a Coke can to me.  One day I would come into school with some wire cutters and go under there myself.

Perhaps this was what faith in God felt like.

Whenever I hear about the Elgin Marbles I imagine they're marbles of this kind. I am completely uninterested in disabusing myself of this fancy.

Maybe one of them is a Tenner Clear.

I'm sure this has happened before. Do you think it has happened before? Don't you remember reading a blog entry by me on the subject of déjà vu?

However in this case it actually has. I did indeed write about déjà vu back in September 2009. I'm not intending to go over the same ground here, but recently woke from a dream with some new insights into what might make this bizarre sensation, this mental feedback, tick.

In the original blog entry I hypothesised that déjà vu was caused by the short term memory (in other words the current experience, the present, the now) being misidentified as long term memory. This does make some kind of sense. However doesn't explain one of the stronger sensations that can be experienced during a promnesiac episode. Often my experience of déjà vu is not so much I'm sure this has happened before but rather I am sure that I have dreamed this before. This makes me inclined to think that déjà vu may be the activation of a system that is usually only intended for use during unconsciousness.

In waking life the short and long term memory have quite clear and separate purposes. The long term is your backstory, who you are, what you're doing here and how you got there. It sits on the organic equivalent of a hard disk, immutable and unchanging from day to day, at least in theory. The short term is the working space of the consciousness, the RAM, the now. You can see how the latter of these two memory types might work just as well when dreaming, but perhaps not the former...

When do dreams actually begin? If you think about it, they don't. There isn't a moment when you settle down in the cinema seat of the Cartesian Night Cinema, hand in a bucket of warm popcorn, the lights dim and the words Our Feature Presentation appear on the screen. Dreams sneak up on you when you're not looking, climb inside your head and attempt to convince you that you were embroiled in this story all along, that the reason it seems a bit incoherent is that you simply weren't concentrating. If you start wondering about this kind of thing too much during a dream you might find yourself having to run away from a monster or trying to explain to everyone on a crowded bus why you don't have any underpants or trousers on.

Any period of awareness that doesn't begin in bed is a very bad thing. In prehistory it would very probably mean that you'd been knocked unconscious by a predator and so feelings of panic and terror would be useful for removing oneself from danger. In the modern world the panic and terror remains even if the blackout is caused by over-drinking. So in order to prevent every dream starting out as a nightmare the brain has to fool you into thinking you were there all along. A large chunk of false short-term memory would do the trick nicely. There was a bit before, even if you can't quite remember what it was now.

Of course this isn't the only way that the dreaming brain has to pull to wool over your sleeping eyes. In order for dreams to make sense your imagined past quite often has to be very different from reality. So a false long-term memory also has to be constructed, one which, provided you don't examine it too closely, will serve to shore up the imaginary present you think you're living through. It's a common occurrence in dreams that you suddenly remember things that of course always were the case, only you'd forgotten. That the Queen used to live next door to you. That you could fly when you put your mind to it. That you could sometimes travel back in time. That you used to be a character in Eastenders. And so on.

This false long-term memory can't be a coherent structure as this would imply that a brand new one would have to be pieced together for every dream, which would in turn have to be scripted in advance. This clearly isn't the case. The false long-term memory must therefore consist simply of a mechanism which, when queried, always replies "Yes, that's right, that's what happened" in order to support whatever absurdity the dreaming brain is currently entertaining as reality.

So if this false long-term memory is accidentally activated during wakefulness and applied to whatever you are currently experiencing you might think it had happened before.

Or perhaps, if the scent of a dream lingers around the response from this mechanism, that you'd dreamed it before.