The Emotion Machine

worse.

That turned out to be a severe limitation, because a Difference-Engine, by itself, has no way to plan several steps ahead—for example, by the methods suggested in §5-5—so it cannot sustain a short-term loss for the purpose of later, larger gains. So, although their system could solve many problems, this limitation seems to have led Newell and Simon to move in other directions.[111] In my opinion, they should have persisted, because this project had so many good ideas that I find it strange that it was not further developed in later years. In any case, we can’t expect any one method to solve every problem—and our forthcoming project will try to embody the concepts that Newell and Simon abandoned.

In retrospect, one could argue that the system got stuck because it was not equipped with ways to reflect on its own performance—the way that people can ‘stop to think’ about the methods that they have been using. However, in a great but rarely recognized essay, Newell and Simon did indeed suggest a very ingenious way to make such a system reflect on itself.[112]

On the positive side, the General Problem Solver was equipped with several ways to reduce each kind of difference, and it even included a place for ways to introduce new kinds of representations.

What if one fails to solve a problem, even after using reflection and planning? Then one may start to consider that this goal may not be worth the effort it needs—and this kind of frustration then can lead one to ‘self- consciously’ think about which goals one ‘really’ wants to achieve. Of course, if one elevates that level of thought too much, then one might start to ask questions like, “Why should I have any goals at all,” or, “What purpose does having a purpose serve”—the troublesome kinds of questions that our so-called “existentialists” could never found plausible answers to.

However, the obvious answer is that this is not a matter of personal choice: we have goals because that’s how our brains evolved: the people without goals became extinct because they simply could not compete.

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Goals and Subgoals

Aristotle: We deliberate not about ends, but about means. … We assume the end and think about by what means we can attain it. If it can be produced by several means, we consider which one of them would be best …[and then] we consider by which means that one can be achieved, until we come to the first cause (which we will discover last).[113]

Section §2-2 considered some questions about how we connect our subgoals to goals—but did not stop to investigate how those subgoals might originate. However, a Difference-Engine does this by itself because, every difference it needs to reduce becomes another subgoal for it! For example, if Joan is in Boston today, but wants to present a proposal in New York tomorrow, then she will have to reduce these differences:

The meeting is 200 miles away.

Her presentation is not yet complete.

She must pay for transportation, etc.

Walking would be impractical because that distance is too large, but Joan could drive, take a train, or an airplane. She knows this ‘script’ for an airplane trip:

Each phase of this script, in turn, needs several steps. She could “Get to the airport” by bicycle, taxi, or bus, but she decides to drive her car, which begins with a series of subgoals like these:

When Joan reviews that airplane trip, she decides it would waste too much of her time to park the car and pass through the security line. The actual flight from home to New York takes no more than an hour or so, and the railroad trip is four hours long, but it ends near her destination—and she could spend all that time at productive work. She ‘changes her mind’ to take the train.[114]

Similarly, when Carol decides to change this into this , she will need to split this job into parts, and that will need several subgoals and scripts.

Then each of those subgoals will turn out to require several more parts and processes—and when we developed a robot to do such things, its software needed several hundred parts. For example, Add a block needed a branching network of subgoals like these:

Each of those subgoals has problems to solve. Choose must not select a block that is already supporting the tower top. See must recognize objects regardless of color, size, and shades of light—and even when they partly obscured by other objects. Grasp must adapt the robot’s hand to the perceived size and shape of the block to be moved. And Move must guide the arm and hand through paths in space that never strike the tower’s top or hit the child’s face.

How do we find out which subgoals we’ll need to achieve before we can accomplish a job? You could discover them by trial and error, or by doing experiments inside your mind, or recalling some prior experience. But perhaps our most generally useful method is to use a Difference-Engine—because every difference that this detects could thereby become a new subgoal for us.

To summarize, our idea is that “to have an active goal” amounts to running a Difference Engine-like process. I suspect that, inside each human brain, many such processes all run at once, at various levels in various realms. These range from instinctive systems that work all the time—like those that maintain our temperatures (and these are so opaque to reflection that we don’t recognize them as goals at all)— up to those highest self- conscious levels at which we keep trying try to be more like the persons we wish we were.

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§6-4. A World of Differences

“Some minds are stronger and apter to mark the differences of things, others to mark their resemblances. The steady and acute mind can fix its contemplations and dwell and fasten on the subtlest distinctions: the lofty