Common Sense

We found a way to make a tower builder out of parts. But Builder is really far from done.

For example, how could Find determine which blocks are still available for use? It would have to “understand” the scene in terms of what it is trying to do.

We’ll need theories both about what it means to understand and about how a machine could have a goal.

Consider all the practical judgments that an actual Builder would have to make. It would have to decide whether there are enough blocks to accomplish its goal and whether they are strong and wide enough to support the others that will be placed on them.

By the time we are adults, we regard all of this to be simple “common sense”. But that deceptive pair of words conceals almost countless different skills.

Common sense is not a simple thing. Instead, it is an immense society of hard-earned practical ideas – of multitudes of life-learned rules and exceptions, dispositions and tendencies, balances and checks.

Dreyfus calls the ability to intuitively respond to patterns without decomposing them into component features “holistic discrimination and association”¹:

When things are proceeding normally, experts don’t solve problems and don’t make decisions; they do what normally works.

As each new group of skills matures, we build more layers on top of them. As time goes on, the layers below become increasingly remote until, when we try to speak of them in later life, we find ourselves with little more to say than “I don’t know.”