The understanding of human beings is vastly taken to be powerful, a source of power, the thing that makes us as a species “Kings over the Earth”. We are not kings. And to understand does not mean you can do anything. It just means that, if you could, you would be more likely to know you could.
Understanding is just a kind of familiarity. It just means you are used to something. You’ve done it times enough that you can reasonably expect to be able to cope with most of the outcomes.
There are some times, though, where different people, with different life histories, can compare their familiarity in matters where their experiences had little in common to one another. How exactly does this work?
While expressed in these terms this does not really sound like an important problem, it is interesting that it frames many issues in the theory of knowledge. Because in some senses perfect communication is impossible since life experiences are never the same (by definition) and thus we cannot avoid the possibility that they are impossible to compare — we can both taste the exact same chicken but we can’t be sure that the taste felt is the same.
Familiarity is a related problem, though not exactly the same. Familiarity is being used to circumstances and circumstances are also impossible to compare.
To be precise, circumstances cannot be compared while you are living them, because you can not guarantee that your perspective is inclusive. Judging from outside, you can sometimes make a fair appraisal of the circumstance. This is almost the definition of a “laboratory”: A structure that allows you to make a fair appraisal of a given circumstance. But life is not a laboratory and familiarity is not something that is easy to export.
The very idea of familiarity does imply that some circumstances are similar to others. We can extract traces of them that are equal. But the whole is never equal, or if it was equal we could not know because we can’t reach the whole of our circumstance.
So the familiarity can be exported and (given some restrictions) it can be measured. We can’t count how many circumstances a given familiarity refers to, because there are infinite circumstances. But we can average how much energy it is needed to make a given familiarity to work in each new circumstance over the long run. In other words, we do not measure the circumstance itself, but the flux of circumstances we are subjected to.
In a meta-way, we also do not measure the other’s circumstance or familiarity, but our experience of their way of acting, and through it their own appraisal of their own flux of circumstances.
Thus what we know about our understanding is not what we know, as for example would appear in a list of subjects in a curriculum or summary. What we know about what we know is a performance average.
One of the words used for understanding is comprehension. Ironically, it comes from “to arrest”. It reflects the wrong perception that we have acquired what we know. But another way to read comprehension is inclusion. In that you arrested it through making it part of you, maybe changing yourself into something that is both yourself and facets of the other at the same time. Arresting through similarity. The control of caring.
So comprehending is trying to shape our familiarities into something that can be exchanged into other’s lives.