There is a philosophical theory about whether things truly exist or not, called solipsism. The main thrust of this theory that we can only be sure of our own existence, not of the existence of anything or anyone outside of us.
A truly solipsistic person can never know whether the people that they meet are real or just figments of their imagination. For all the solipsist knows, they are just a brain floating in a tank, experiencing whatever stimuli are zapped into their vestigial spinal cord.
Solipsists are rarely fun at parties, not least because they can’t be sure that anyone else has actually shown up.
Perhaps that’s a little unfair to solipsism, but this theory brings up an interesting question.
Can we ever be sure that anyone else experiences the world the way we do?
Do we experience things the same way?
If you and I both see a red rose, we both detect the same wavelengths of light. Assuming that neither of us is colourblind, we will both say that the rose is red. But do we experience red the same way?
If we could swap minds, you might discover that what I call red looks more like green. But we both call it red because that is the name we give to that wavelength of light. My red is no less red than your red¸ they just look subjectively different.
This is due to what is known in psychology as qualia.
Qualia are the personal subjective experiences of the world around us. We can measure and quantify most stimuli and be sure they are the same objectively, but we cannot be sure that the qualia are the same.
Take for instance your standard airconditioned office. Some people like a cooler temperature and some like a warmer temperature. If I adjust the aircon to be a temperature I like, this would make some people think it is too cold, or too warm. To them it feels colder or warmer than it does to me. The temperature is the same, but the qualia are different.
Then of course there is the problem of whether other people are conscious at all.
Are you conscious?
I know that I am conscious because I have my own experiences. Given that I am a human and presumably not special in this regard (not matter what my mother tells me), I can assume that other humans are conscious too.
But, I don’t know for a fact that they are! I don’t know whether you, the reader, are conscious actually. Although if you’ve made it this far, possibly not.
In 1995 a researcher from the Department of Linguistics and Philosophy in MIT, called Ned Block, wrote a paper called On a confusion about a function of consciousness.
In it, he marked the difference between two types of consciousness:
Phenomenal-consciousness is the ability to experience the world, in colours and smells and emotions, etc.
Access-consciousness is the ability to act and speak, to reason and to rationalise.
We can easily examine whether a person or an animal has access-consciousness, otherwise known as A-consciousness. If a person is able to use some information we give them, and make a response, then they would have to have A-consciousness.
We cannot, however, easily examine whether a person has phenomenal-consciousness, or P-consciousness. This is because P-consciousness can’t be communicated. If I asked you to describe blue you might talk about what things are blue, or how blue makes you feel, or perhaps write a long-winded poem about blue as a metaphor. What you could not do would be to make me experience blue the way you do.
You (presumably) know you have P-consciousness, but you can’t prove to me that this is the case. And I can’t prove to you that I do either.
Hemispatial Neglect and Zombies
This brings us to two fun models. We’ve said that you can’t prove that anyone has P-consciousness, but can you separate the two types of consciousness entirely.
Well, you can separate them a little.
There is a condition called visual hemispatial neglect. This is where a person is unable to pay attention to one half of their vision, and so they are entirely unaware of what is there. They lack P-consciousness for their left visual field.
However, they can still use information that is there. In one experiment, patients were shown words in the area of their vision that they were blind (eg. TEA) and asked to pick from a selection the word that matched it (eg. CUP). They were able to do this better than chance, despite having no awareness of what the first word was. This shows that they had some access to that information (A-consciousness) even though they had no experience of seeing it (P-consciousness).
This ability, called blindsight, is a powerful example of how a person can act as though they have P-consciousness even though they don’t.
To think about a person who only has P-consciousness and not A-consciousness, we have to think about zombies. In modern interpretations, zombies are shambling creatures that lust for human flesh and brains.
Zombies cannot reason or make use of information, they solely act on impulse – the main one being hunger. So, it might be that a zombie has P-consciousness but not A-consciousness.
This is not a brilliant example however, as zombies A) don’t really exist and B) still use some A-consciousness to track their victims.
Neither of these examples is perfect, but they do illustrate some differences between these types of consciousness.
Are Computers Conscious?
Finally there is the question of whether computers are conscious. Not necessarily in a Skynet, Her, or Ex Machina way. But do computers exhibit A-consciousness?
There is a philosophical problem called the Chinese Room, invented by John Searle in 1980. This is related to the Turing Test, where a computer must convince a human that it is human itself.
It goes roughly as follows:
A person sits in a room with a book, a notepad, and a pencil. The room has no windows and only one door, which has a letterbox (or mail slot). From time to time a card is pushed through the letterbox with some Chinese characters on it. The person, who cannot read Chinese, takes the card and opens up the book. The book contains a vast amount of instructions, each pertaining to different possible cards. The person finds the right instructions and diligently copies the characters from the book to a sheet of paper. They then post the piece of paper out through the letterbox.
To someone who can read Chinese, it would appear that whoever is inside the room is also fluent in Chinese. They can hold a full and interesting conversation about any topic, so long as it is posted through the letterbox.
Does the person in the room understand Chinese? Does the book? Or the room itself?
The Chinese Room can be said to have A-consciousness, as it is capable of rationalising in its own way, and seems to an outside observer to be conscious. But is it really conscious?
Remember that we have no real way to measure if something has A-consciousness as well as P-consciousness, so is it impossible that the Room has P-consciousness too?
This is about the point where science gives way to religion and philosophy unfortunately, or fortunately if you prefer that!
I will leave you with one question though, which may keep you up tonight. Everyone around you acts as though they are as conscious as you are. Are you sure they are? Are you sure you aren’t a Chinese Room too?