Knowing that We Know

We all know stuff. Some of it is the obvious sort of things that we do not even think about, such as ‘If I don’t put this foot down I will fall over’. Other stuff we know we do think about; this is perhaps the things we learnt at school, such as ‘Henry VIII had six wives’ or ‘the square root of 64 is 8.’ Sometimes we have to think about it, or ransack our memories for the answer (say to the question ‘what were Henry VIII’s wives called?’).

The things that we know divide, then, into two classes, at least roughly. The things which we know automatically, such as catching a ball or riding a bicycle, and the things we have to think about. Granted, originally, we had to learn to catch a ball or ride a bike, but once we have done so, we can pretty well think of other things, so long as nothing unexpected happens.

The thing is that while many of us can ride a bike, swim or undertake a myriad of other activities, we are likely to struggle to explain how we come to do them. We can show someone how to ride a bike by riding a bike in front of them. We can explain that you pedal and hold the handlebars, and even that moving forward helps stability and steering, but we cannot explain exactly how a bike is ridden. We know how to ride a bike, but we cannot tell how to ride a bike.

A fair bit of life is like this, I suspect. We watch a TV chef rustle up a fabulous (looking, at least) dish out of a few dubious looking vegetables and the breast of a woodcock, without a recipe or, apparently, any idea of what the final product will look or taste like. They know what they are doing. This is experience, granted, but also some slightly mysterious knowledge that we cannot quite define; perhaps ‘intuition’ might be used to describe it.

The upshot of this is that, if you think about it a bit, we know far more than we can tell. This is not, by the way, original to me. The chemist and philosopher Michael Polanyi observed this a fair time ago, in his book Personal Knowledge, among other works (Polanyi, M., Personal Knowledge: Towards a Post-Critical Philosophy (Chicago: University of Chicago, 1962)). The critical philosophy in the sub-title refers, I think, to the ideas of Kant and his critical philosophy.

I have already given some illustrations of this principle; there are many more. In a more technical sense, there was a time when I could tell whether a vacuum system was leaking from the sound of the pumps. A pump evacuating a chamber which is leaking makes a different sound from a pump which is maintaining a vacuum at a certain low pressure. I can tell you that much, but how the sounds differ is a matter of experience: the pitch of the pump with the leaky system is lower as the pump is working harder. How much lower and how you know whether it is significant or important is a matter of practice and knowing the system and that means that you have to attend to the noises that the pump makes under various conditions, not just read off the pressure from the gauge.

My personal knowledge will differ from your personal knowledge. Our experience and what we have attended to are different, even if we grew up in the same country, trained in the same subjects and so on. That does not mean, however, that our knowledge is entirely subjective. ‘It works for me’ only goes so far. After all, murdering someone might work for me, but it certainly will not work for the other person, or for the criminal justice system. We actually have to agree on a great number of things before we hold a conversation about things we might not agree over.

One of Polanyi’s problems with the scientific world is that science (by which we mean physical science here) makes facts impersonal. The scientific world agrees, for example, that the Schrodinger equation gives a reasonable description, under many circumstances, of how the atomic-scale world works. That knowledge is held by the scientific community, somehow. It is in the courses on physics you might undertake at university, it is in the textbooks and so on.

What is often not observed, but is also true, is that the Schrodinger equation is also, and most importantly, in the mind of those physicists who use it to solve problems. It is they who write down the equation, who add the boundary conditions for the given problem they are trying to solve and attempt to obtain the answers that they want. How to do this can only be partially taught. Some of it is personal knowledge – it is why when learning a subject you have to do lots of boring exercises, to build up your personal knowledge of the subject.

One of the things it is a bit difficult to convince young researchers of is that when they come to defend their thesis, they are the world experts on the subject (or they should be). Of course, they will not feel like it, but the examiners are not strictly speaking experts. My internal examiner told be over coffee on the day of my viva that I should expect some stupid questions: ‘Not because we are trying to trick you or trap you, but because we do not know.’ I had the personal knowledge of the subject; I had done the experiments, examined the data, analysed the results and written every word of the thesis. The knowledge gained was at least partly expressed in the thesis, but only partly. I also knew what a leaky vacuum system sounded like, and this was not an explicit part of the examination.

The danger is that we then start assuming all knowledge is personal and thus everything is subjective, or relative to the individual. That is, of course, as untrue as the claim that the only things we know are publicly available facts. But that discussion is for another time.