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Society of Mind

8.6 levels

We sometimes think of memory as though it could transport us back to hear the voices of times gone by and see the sights of the past. But memory can't really take us anywhere; it can only recall our minds to prior states, to visit what we used to be, by putting back what was in the mind before. We introduced the level-band theory to provide a way for a memory to encompass some range or level of detail of descriptions, as when, in remembering that kite experience, certain aspects were recorded firmly and others weakly or not at all. The concept of a level-band can be applied not only to descriptions of things, but also to our memories of the processes and activities we use in order to achieve our goals — that is, the mental states we re-create that once solved problems in the past. The problems we have to solve change with time, so we must adapt our old memories to our present goals. To see how level-bands can help with that, let's now return to Play-with-Blocks — but this time let's suppose that our child has grown to maturity and wants to build a real house. Which agents from the old building-society can still be applied to this new problem?

The new house-building agency can certainly use many of Tower Builder's skills. It certainly will need Add's lower-level skills like Find and Get and Put. But House Builder won't have so much use for Tower Builder's highest-level agents like Begin and End — because these were specialized for making towers. Nor will it have much use for Builder's lowest-level skills, like those in Grasp, because picking up such small blocks isn't the problem. But most of the skills embodied in Builder's middle level-bands will still apply. These seem to embody the sort of knowledge that is most broadly and generally useful, whereas uppermost and lowest level-bands are more likely to be based on aspects of the problem that are specific to an older goal or to the particular details of the original problem. But if our memory machinery has been designed so that the contents of those distant fringes can be easily detached, the extra knowledge stored in them will rarely do much harm and can often be helpful. For example, Tower Builder's fringe details could tell us what to do in case our house should grow very tall or require a high chimney.

We started out by using level-bands for describing things — but we ended up using them for doing things! In the next few sections we'll see that it is no accident that level-related ideas play many different roles in how we think.