Are there units of thought? An interesting conversation here between Asifa Majid and Jon Sutton. There are a number of interesting points, but the one that I found most thought-provoking was the reference to searching for those tantalising units. I think I had been lazily assuming that any such search had been abandoned long ago – if not quite with the search for perpetual motion and the universal solvent, then at least a while back.
I may, though, have been mixing up two or more distinct ideas here. In looking for the units of thought we might be assuming that there is some ultimate set of simplest thought items, a kind of periodic table, with all thoughts necessarily built out of combinations of these elements. This sort of thinking has a bit of a history in connection with language. People (I think Leibniz was one) used to hope that if one took all the words in the dictionary and defined them in terms of other words, you would eventually get down to the basic set of ideas, the ‘primitives’ which were really fundamental. So you might start with library, define it as ‘book building’, define building as ‘enterable structure’, define structure as ‘thing made of parts’ and feel that maybe with ‘thing’, ‘made’, and ‘parts’ you were getting close to some primitives. You weren’t really, though. You could move on to define ‘made’ as ‘assembled or created’, ‘assembled’ as ‘brought or fixed together’… Sooner or later your definitions become circular and as you will have noticed, alternative meanings and distinctions keep slipping through the net of your definitions.
The idea was seductive, however; linked with the idea that there was a real ‘Adamitic’ language which truly captured the essence of things and of which all real languages were corruptions, generated at the fall of the Tower of Babel. It is still possible to argue that there must be some fundamental underpinning of this kind, some kind of breaking down to a set of common elements, or languages would not all be mutually translatable. Masjid gestures towards another idea of this kind in speaking of ‘mentalese’, the hypothetical language in which all our brains basically work, translating into real world languages for purposes of communication. Mentalese is a large and controversial subject which I can’t do justice to here; my own view is that the underpinnings of language, whether common or unique to each individual, are not likely to be another language.
Could there in fact be untranslatable languages? We’ve never found one; although capturing the nuances of another language is notoriously difficult, we’ve never come across a language that couldn’t be matched up with ‘good enough’ equivalents in English. Could it be that alien beings somewhere use a language that just carves the world up in ways that can’t be rendered across into normal Earth languages? I think not, but it’s not because there is any universal set of units of thought underneath all languages and all thoughts. Rather, it is first because all languages address the same reality, which guarantees a certain commonality, and second because language is infinitely flexible and extensible. If we encountered an entirely new phenomenon tomorrow, we should not have any real difficulty in describing it – or at least, it wouldn’t be the constraints of language that made things difficult. Equally we might have difficulty working out the unfamiliar concepts of an alien language, but surely we should be able to devise and borrow whatever words we needed (at this point I can feel Wittgenstein’s ghost breathing impatiently down my neck and insisting that we could not understand a lion, never mind an alien, but I’m going to ignore him for now).
So perhaps the search for the units of thought is not to be understood as a search for any kind of periodic table, but something much more flexible. Masjid refers to George Miller’s famous suggestion that short term memory can accommodate only seven items, plus or minus two depending on circumstances. This idea that there is a limit to how many items of a ‘one-dimensional’ set we can accommodate is appealingly tidy and intuitive, but it obviously works best with simple items; single tones or single digits. Even when we go so far as to make the numbers a little larger questions arise as to whether ‘102’ is one, two, or three items, and it only gets worse as we try to deal with complex entities. If one of the items in memory is ‘the first World War’ is it really one item which we can then decode into many or an inherently complex item?
So perhaps it’s more like asking how many arms an amoeba has. There is, in fact, no fixed set of arms, but for a given size of amoeba there may well be a limit on many pseudopodia it can extend at any one time. That feels more like it, though we should have to accept that the answer might be a bit vague; it’s not always clear whether a particular bit of amoeba counts as one, two, or no pseudopodia.
Or put it another way: how many images can a digital screen show? If we insist on a set of basic items we can break it down to pixel values; but the number of things whose picture can be displayed is large and amorphous. Perhaps it’s the same with the brain; we can analyse it down to the firing of neurons if we want, but the number of thoughts those neurons underpin is a much larger and woollier business (in spite of the awkward fact that the number of different images a digital screen can display is in fact finite – yet another thorny issue I’m going to glide past).
And surely the flexibility of an amoeba is going a bit too far, isn’t it? Masjid points out some evidence that our choice of thought items is not altogether unconstrained. Different languages have different numbers of colours, but there is a clear order of preference; if two languages have the same number of colour words, there’s an excellent chance that they will name more or less the same colours. Different languages address the human forelimb differently, some using words that include the hand while others insist that the two main halves are spoken of separately, never the arm as a whole. Yet no languages seem to define a body part composed of the thumb and first half of the forearm.
Clearly there are two things going on here; one is that our own sensory apparatus predisposes us to see things in certain ways – not insurmountable ones that would prevent us understanding aliens with different biases, but universal among humans. Second, and perhaps stranger, reality itself seems to have some inherent or salient forms that it is most convenient for us to recognise. Some of these look to be physical – a forearm just makes more sense than a ‘thumb plus some arm’; others are mathematical or even logical. The hunt for items of thought loosely defined by our sensory or mental apparatus is an interesting and impeccably psychological one; the second kind of constraint looks to raise tough issues of philosophy. Either way I was quite wrong to have thought the hunt was over or abandoned.