What Is Understanding?

Dustin A Smith

This paper will help you to understand understanding. Although it may be difficult to articulate what understanding is, people have no trouble identifying understanding, so I will start out with examples.

Let's look at a situation where we would say someone ``does not understand'' something. Suppose a young child came up to you and said, “If you drink too much, you will have a hangover.”

Yes, you agree with the child, but wonder: How did the child come to know this? Presumably they learned this from someone else, and not from heavy drinking. But, do they understand what they are saying?

First, let us start with an extreme. Maybe the child is just paroting a sequence of phonemes,


and do not even know where the words begin and end. But, more likely, the child will know what most of the words mean, and was able to establish some concept of relating the action:

A person drinking too much to have the direct effect of causing the person to have a hangover

Grant the child this ability to understand the link between an action and a consequence, but these are just regularities of the ways we composes our sentences (IF (X) THEN (Y)). Even if the child knows this much, do they recognize that drinking implies drinking alcohol and that a hangover is a headache? Surely they would have to know this much before we would finally agree that they understand what they are saying. Let us ask it:

See, we were right, our straw child did not understand! But we would have granted the child more credit if they could have provided an answer we think is sensable:

Now we are talking understanding (and incrimination of the parents). What is understanding here?

"Understanding is the ability to connect a representation to many other representations. If you understand something in only one or two ways, you scarcely understand it at all."1

Here in Minsky's explanation, you understand things when you have redundant connections and alternative routes, so that when one line of thinking fails, you are not stuck.

Having an index is the first step towards understanding

Look at these various symbols that all are associated with the word symbol apple:



Above are many cues which allow apple related memories to be retrieved. These memories may have different natures (company, fruit, computer, toy, food, plant, the word 'apple' ...) When you are reasoning about one of these, you may be using, or switching between, many representations at once.

Understanding is marked by interconnections, but the first step toward understanding is being able to find the right represention from your perception. In other words, you need to have a way to retrieve the correct associations in the first place---think of someone speaking a foreign language, where you are not sharing the same indices: you cannot "understand" them.

It is interesting to ponder how much of our representations are associated with perceptual cues, versus those indexed with language (reading, speaking) which require very little interaction with the environment.

Back to our example with the child. If the child were to have made the statement while you were drinking a glass of wine, then they would have demonstrated this indexing principle. You would imagine they made the connecton between the statement Drink Too Much with their observation of you drinking.

Understanding is answering the right questions

Another property of understanding is having the correct associations for a given index. There are no "correct associations" in absolutes, but we have generally agreed upon connotations for the concepts we try and communicate (some call them "denotations," [2]). Some of these associations can activate other indicies (see K-Lines). Recall how we discovered whether the child understood what they were saying: through interrogation. Answering typical questions about the topic is the hallmark of understanding.

What constitutes a typical question? Questions depend on the goal that you are pursuing, because the answer will allow you to fill in a slot on one of your representations or plans.

This is left vague, but the specifics are difficult to discuss, or even speculate about, without some model of how the knowledge being represented.

Appendix: Failures of Understanding

Here are some general types of understanding failures:
  1. Too few connections
  2. Bad connections (misunderstanding)
  3. Not having an index for retrieval (ie, not knowing a word)
  4. Wrong symbols used in index (a communication failure)

References & Meanderings

[1] Marvin Minsky, The Society of Mind and The Emotion Machine (2007).

[2] The term denotation has the unjustified connotation that there is something more "true" about the particular set of associations because they are documented. In my view, denotations are just the majority's conensus of connotations (and by the time they are documented and published, they are probably outdated).