Saturday, March 5, 2011

The brain in the vat

I haven’t, so far, burdened you with news of my Epistemology class, fraught as it is with scepticism, realism, anti-realism, a priori knowledge, foundationalism, coherentism, internalism, externalism, semantic externalism, contextualism, invariantism....arrgghhhh!!!!! But recently some of these –isms were brought into focus through the consideration of a rather popular philosophical thought experiment known as ‘the brain in the vat’ (or BIV to its friends). Epistemology is the study of knowledge: what it is, how we get it, how we know we know anything, and other such interesting and fundamental issues.

In the ‘brain in the vat’ scenario, you are to imagine a brain which is en-vatted in a nutritive liquor, perhaps by a mad scientist, perhaps it just evolved that way; and it is hooked up to a computer which sends signals to it along its neural pathways. These signals reproduce exactly the sensations and thoughts that the brain would have if it was at home in a human body. Now, say this BIV had a thought of a tree. Say you have a thought of a tree. Qualitatively, the two thoughts are the same, because the computer has sent signals to the BIV which ensure that. Can we – should we – conclude that the two thoughts, yours and the BIV’s, are identical?

A philosopher who is a Semantic Externalist will say ‘no’. And his or her reason will be because the thought of a tree is meaningless unless it is caused by the external experience of a tree. In other words, your thought of the tree is informed by, referenced by, your having seen a tree at some time. The BIV’s thought of the tree is not caused by any such reference.

Why does this matter? I hear you ask. Actually, this is pretty fundamental. The problem in Epistemology is a pesky character named The Sceptic. This character is sometimes personified in a renegade philosopher, sometimes in a member of the doubting laity (such as your good self, perhaps). But even if only theoretical, The Sceptic is always there. He or she is the person who asks: ‘but how do you know that?’ One of his/her favourite questions is: ‘how do you know the external world exists?’ How do you know you have a hand? How do you know there is a tree there? How do you know you are not just dreaming? Or hallucinating? How do you know that an Evil Demon (or deceiving god) hasn’t taken you over and implanted these false ideas in your mind?

You think this sounds too weird to be bothered about? have a look at this particularly weird website.  I also refer you to the movie ‘The Matrix’, which was based on the hypothesis that the entire human race had been placed into giant vats and fed a virtual reality at the hands of a malignant artificial intelligence. You might also consider ‘The Truman Show’. How do you know you aren’t in one of those situations?

Jim Carey wonders...
Unless we can show that the ‘brain in a vat’ premise is wrong, we can’t refute the sceptic who says: ‘but how do you know that what you think you see, even what you think you think, is reality?’ The BIV scenario also throws up interesting features about the relation between mind and world, and meaning and reality, which get a lot of philosophers excited, if no-one else.

So what about the Semantic Externalist who says that the BIV hasn’t really had a ‘thought’ about a tree, because it has never experienced a tree? How does this help us refute the sceptic? If you’ll just bear with me, I now have to bring in a teensy weensy syllogism or two. This is a version of the sceptic’s argument:

1.       You do not know that you are not a brain in a vat.

2.       If you do not know that you are not a brain in a vat then you do not know that you are currently drinking water.

3.       So, you do not know that you are currently drinking water.

To overcome this valid and seemingly true logical argument, it is necessary to attack either (or both) the first or second premise. For example, you could try attacking the first premise by arguing that the mind is a complex physical system and it is not possible for your mind to exist in a matterless world (you would then be called a ‘Materialist’). You could also argue that the second premise is not logically sound.

Perhaps the anti-sceptic could come back with:

1.       I think that water is wet.

2.       No brain in a vat can think that water is wet.

3.       So, I am not a brain in a vat.

You will notice that to support premise 2 above, it is helpful to argue that the BIV’s ‘thoughts’ are not causally based and therefore it does not ‘know’ that water is wet.

Have I lost you? I think I’ve had enough myself....If you want to read more about it, the Wikipedia short-version is here; and a more scholarly Stanford Encyclopedia entry is here. 

My Epistemology lectures are given by A C Grayling, whom I have mentioned before on this blog. The lectures are erudite, swift (we have never yet filled the allotted two hours) and – to me - obscure. Professor Grayling now and then says airily “as you will know from your undergraduate epistemology...” Yeek! Since I don’t have any undergraduate epistemology, this necessitates a lot of back-reading and furious study between lectures. I make frantic notes about things I’ve never heard of (Gettier problems? What’s a Gettier problem?) and dash home to look them up. Not all of them are as dramatically interesting as the brain in a vat.

The Prof.
This week Professor Grayling favoured the class with a glimpse of his new book, forthcoming in April. It is called “The Good Book – A Humanist Bible”. It is a large hard-cover tome, vying with The Bible in terms of door-stopping usefulness. He explained that The Bible is (as you probably know) a collection of a wide variety of documents from antiquity, put together by many different authors, and heavily redacted – that means cut and pasted, inserted and rearranged, with, as Professor Grayling put it, inconvenient ‘nots’ removed: edited, in a word. He has followed the same process with his Humanists’ Bible, drawing on many historical texts, ‘shamelessly plagiarising’, as he also put it. He too has redacted and edited and re-arranged these texts. His criteria was that none of those he chose should refer to a divine being, or encourage adherence to the word of a divine being, or promise an afterlife. He told us there was a lot of good stuff in it...I will naturally snap up a copy when it hits the shops.

The book is already on on-line bookshop sites fro pre-order. Here's the blurb:

Drawing on the wisdom of 2,500 years of contemplative non-religious writing on all that it means to be human - from the origins of the universe to small matters of courtesy and kindness in everyday life - A.C. Grayling, Britain's most popular and widely read philosopher, has created a secular bible. Designed to be read as narrative and also to be dipped into for inspiration, encouragement and consolation, "The Good Book" offers a thoughtful, non-religious alternative to the many people who do not follow one of the world's great religions. Instead, going back to traditions older than Christianity, and far richer and more various, including the non-theistic philosophical and literary schools of the great civilisations of both West and East, from the Greek philosophy of classical antiquity and its contemporaneous Confucian, Mencian and Mohist schools in China, down through classical Rome, the flourishing of Indian and Arab worlds, the European Renaissance and Enlightenment, the worldwide scientific discoveries of the 19th and 20th centuries to the present, Grayling collects, edits, rearranges and organises the collective secular wisdom of the world in one highly readable volume. Contents of this title include: "Genesis"; "Proverbs"; "Histories"; "Songs"; "Wisdom Acts"; "The Lawgiver Lamentations"; "Concord Consolations"; "Sages"; and, "The Good Parables".
He told us that his 'Genesis' begins with the apple falling from the tree in Newton's garden.

Meanwhile, Professor Grayling hasn’t yet issued any essay questions for Epistemology, which on the one hand means I don’t have to start the essay struggle; but on the other hand is merely putting off the evil day. Perhaps I am just a brain in a vat and none of this is real.

Images from:

No comments:

Post a Comment