Saturday, January 12, 2013

The Science of Common Sense

How do 'things' really work? When people begin to answer that question, on various topics, for themselves, it should be uncontroversial to say that they are using their minds. Let us, for the purpose of this discussion, sidestep the common-sense term mind (more on that later), and say that we're discussing the brain, part of our biological endowment. Since people are not conscious of most of what goes on in their body, they are similarly not conscious of what goes on in their mind. So when they begin to think "How does the mind really work?" most of the actual work going into forming and answering this question, is something they are doing naturally, work they are unaware of -- it is unconscious work. In the same way that you are not conscious of the mechanism that allowed you to digest breakfast, you are not conscious of how you learn, how you think, how you speak, how you communicate. These things are inaccessible to introspection (thinking that they are is an ancient mistake, mostly associated with John Locke). This is not because you're being insensitive. It is because these are obscure mechanisms, and uncovering them is a hard biological problem, harder than understanding, say, how we digest breakfast, which is itself only roughly understood. This conversion of something we think we know, into real questions about how things work, and the struggle to know the answers, and even consider what form the answers may take, is science. It is obviously very far from common sense, on any topic. Science turns everyday, commonsense things into mysteries.

So, we may think that, say, we communicate by "agreeing on the meaning of terms", because that's a high-level description of something commonsense that we do everyday. But if you try to apply this to the actual mechanism with which we communicate, our minds, it is simply not true. We can communicate only because we are born with essentially identical mechanisms that see the world and assign meaning to it in nearly identical ways. The assignment of a term to these meanings in the head happens naturally, not by agreement, and the method of assignment is so highly determined that the network uncovered by fMRI's of our brain, for the meaning an isolated idea or word, is essentially the same across languages and individuals. We did not learn our language by "agreeing on the meaning of terms", sensible as this sounds, but instead by the natural biological development of our language faculty as we grew up. The "assigned terms" are almost never consciously "assigned", and those which we do assign are the most trivial part of what we are doing when we are thinking or speaking in a language. Meaning is, instead, highly determined by our biology. Not only does every language have noun phrases, verb phrases, nouns and verbs, etc., but when we say screwdriver, in any language, the same network in our brain lights up, which means that we really can only understand a screwdriver in one way. Our interaction with the word is highly species-specific (the conceptual overlap with other animals is still unknown) and this is what allows us to communicate.

It is also what allows us to learn. So, we do not learn by "repeating the same thing over and over". That's "common sense" because this is something we do to force ourselves to remember something under pretty unusual circumstances. But actual learning and memory do not operate in this way. There are parts of our brain which are biologically structured to unconsciously learn certain things in particular ways, and that's most of what we do. When we learn something about an "object", our brain has somehow already divided the world into "objects" and "predicates" so that we could learn something. An that's just the tip of the iceberg.

While these ideas on cognition have recently started to stare us in the face with current neural imaging technology (for example, the work of Marcel Just) they resurfaced in the linguistic work of Noam Chomsky and the cognitive science revolution in the late 1950's, which was inspired partly by all the talk from the 40's and 50's of the computer as a "giant brain" ... which went hand-in-hand with discussion of the brain as a "giant computer". From this perspective, "common sense" was about as useless in helping us determine what "memory" is, as it is in helping us figure out what an "atom" is.

These issues have been discussed for thousands of years -- Plato knew there was innate knowledge (see the dialogue known as "Meno"); Galen knew that the brain was the seat of consciousness, and Nemesius that different parts of the brain provided different functions; Proclus knew that ideas had some kind of fundamental structure; Basil of Caesarea knew that the meanings of words were notions in the mind rather than the structure of things in the outside world.

These views of the mind as highly-structured are often pushed aside for a "common sense" or "pragmatic" views of the mind as a Tabula Rasa, a blank slate or a network of associations among identical elements, which mysteriously takes impressions from the outside world. Nothing like this has ever been found in a living creature, and yet the idea recurs many times, sometimes for engineering reasons (see the current state of computer engineering and its machine learning sub-field) and sometimes because the theories, of obscure qualities underneath common sense, were often badly invented and not too useful. Celsus reviews the state of medical theories at about the time of Tiberius, and says that while you need to think hard about what you're doing, and talk to as many other doctors as possible about underlying causes, experience seems to trump the theoretical side of medicine. In the 18th century, the great Scottish Enlightenment physician William Cullen humbly proclaims that, while we must search for the causes of disease, we must also realize that we are very badly equipped to do so, and our imagination can often leap well beyond any grounding in reality. In physics, this was well known: Newton "frames no hypothesis" because he'd reached the limit of what could be reasonably said about gravity. He had a theory, of course: he had modeled what he could. But anything else would be invention.

Unfortunately Tabula Rasa is a theory too. And a fanciful one at that. It has been demonstrated, repeatedly, to be only useful as an engineering tool, not as a biological model. It may be common sense, but, as we've seen, that doesn't make it science.

Beyond being discarded as a tool for understanding, though, there may be another role for common sense in science.

The fact that we, and other creatures, have a common sense, is critically important. The structure of common sense, while complex, seems to have patterns, which we can begin to examine empirically. In the same way that modern linguistics used natural evaluation ("is this sentence grammatical?") as the basis for experiment, we can perform non-invasive tests upon ourselves to find the structure and contour of the faculty of common sense. This can be backed up by fMRI studies on the structure of common sense, so that we don't get lost in fanciful theoretical discussions (including those dead-end Tabula Rasa ones ... the fMRI could have stopped behaviorism at a very early stage).

We could, in this way, also study what we think of as mind, in the common sense notion, including not just the structure in our brain that represents this word 'mind', but also the way we think about our abilities, methodologies, et cetera.

Beyond that, of course, is one of the central concerns of this blog, namely, what part of common sense is closely tied to parts of the laws of nature? Well, although on a simple level the answer is "everything", what I mean is: which part is genetic, which part is epigenetic, which part was shaped by selective pressures, which by biophysics, and which part of our understanding, feeling, common sense and other natural endowment, is related to structure in nature that we are just beginning to study (for example, in the Evo-devo movement in biology). Although we know something complex is behind all this, and that we don't understand much of it, we can't really approach those questions in an organized way until we start to understand  the structure of common sense in our mind, along with our other faculties such as imagination, memory, feeling etc.

Christopher Alexander's work represents a pragmatic waypoint in this scientific project: a point where we can acknowledge that something is going on (i.e., the evident structure of things with feeling is different than things which lack it) and that we can use it (use feeling and a good unfolding sequence to create something with feeling) and acknowledge that we need to outline a scientific program to, someday, actually uncover what is going on.