This is my first Marvin Minksy book. I've read about his ideas, and probably read a few articles by him. The book is well written and covers many ideas on how the brain might work. It took me a while to read it, because there was so much information.

He uses a platontic-dialectic style by injecting rhetorical comments/questions by characters (Citizen, Student, etc.). The device worked ok in this book, but I found it a bit tedious. Perhaps I'd prefer a simple rhetorical question than the text interspersed with fictional character comments.

[p5] Citizen: I still think your view of emotions ignores too much. For example, emotional states like fear and disgust involve the body as well as the brain, as when we feel discomfort in the chest or gut, or palpitations of the heart, or when we feel faint or tremble or sweat.

I agree that this view may seem too extreme-but sometimes, to explore new ideas, we need to set our old ones aside, at least temporarily. For example, in the most popular view, emotions are deeply involved with our bodies' conditions. However, Chapter 7 will take the opposite view, by regarding our body parts as resources that our brains can use to change [p6] (or main rain) their mental stares! For example, you sometimes Can make yourself persist at a plan by maintaining a certain facial expression.

[p6] Accordingly, when we design machines to mimic our minds-that is, to create Artificial Intelligences-we'll need to make sure that those machines, root, are equipped with sufficient diversity:

If a program works in only one way, then it gets stuck when that method fails. But a program that has several ways to proceed could then switch to some other approach, or search for a suitable substitute.

This idea is a central theme of this book-and it is firmly opposed to the popular view that each person has a central core-some sort of invisible spirit or self-from which all their mental abilities originate. For that seems a demeaning idea-that all our virtues are secondhand-or that we deserve no credit for our accomplishments, because they come to us as gifts from some other source. Instead, I see our dignity as stemming from what we each have made of ourselves: a colossal collection of different ways to deal with different situations and predicaments. It is that diversity that distinguishes us from most of the other animals-and from all the machines that we've built in the past-and every chapter of this book will discuss some of the sources of our uniquely human resourcefulness.

I enjoy the concept of suitcase-like words. It's important to be able to pick apart the words we use every day as if they mean one thing; they don't. Words are complex conceptions. Understanding words requires talking about them in a particular context, and even then, we have different connotations for the same word.

[p97] All this should lead us to conclude that consciousness is a suitcase-like word that we use to refer to many different mental activities, which don't have a single cause or origin-and, surely, this is why people have found it so hard to "understand what consciousness is." The trouble was that they tried to pack into a single box all the products of many processes that go on in different parts of our brains-and this produced a problem that will remain unsolvable until we find ways to chop it up. However, once we imagine a mind as made of smaller parts, we can replace that single, big problem by many smaller, more solvable ones-which is just what this chapter will try to do.

The following is a strong argument for testing as a critical part of software evolution.

[p105] The same sort of constraint also seems to apply whenever we try to improve the performance of any large system. For example, after every change we make in an existing computer program, we usually find that this has created additional bugs-and then we need to make yet more corrections. In fact, many computer systems eventually become so ponderous that their further development Stops, because their programmers can no longer keep track of what all the previous programmers did.

Similarly, it appears that our brains result from processes in which each new part in based on some older designs, but also includes exceptions to it. Indeed, I suspect that large parts of our brains work mainly to correct mistakes that other parts make-and this is surely one reason why the subject of human psychology has become so hard. We can expect to discover neat rules and laws that partly explain many aspects of how we think. However, every such "law of thought" will also need a sizable list of exceptions to it. So psychology will never be much like physics, in which we frequently find "unified theories" that work flawlessly.

[p112] Aaron Sloman 1994: "People are too impatient. They want a three-line definition of consciousness and a five-line proof that a computational system can or cannot have consciousness. And they want it today. They don't want to do the hard work of unraveling complex and muddled concepts that we already have, and exploring new variants that could emerge from precisely specified architectures for behaving systems."

[p180] I do not mean to dismiss all prospects of building a baby-machine, but I suspect that any such system would develop too slowly unless (or until) it was equipped with adequate ways to represent knowledge (see Chapter 8). In any case, iv seems fairly clear that human brains are innately equipped with highly developed ways to learn (some of which don't start to operate until long after birth). The researchers who have tried to build such machines have used quire a few ingenious schemes, but it seems to me that each of those machines got stuck because of not having ways to overcome one or more problems like these:

[p181] The Optimization Paradox: The better a system already works, the more likely each change will make it worse-so it gets more difficult for it to find more ways to improve itself

The Investment Principle: The better a certain process works, the more we will tend to rely on it, and the less we will be further inclined to develop new alternatives--especially when a new technique won't yield good results until you become proficient with it.

The Complexity Barrier: The more that the parts of a system interact, the more likely each change will have unexpected side effects.

Evolution is often described as a process of selecting beneficial changes but most of evolution's work involves rejecting changes that have bad effects! This surely is why most species evolve to occupy narrow, specialized niches that are bounded by all sorts of hazards and traps. It is not often recognized that while genetic evolution can "learn" to avoid the most common kinds of mistakes, it is virtually incapable of learning large numbers of very uncommon mistakes. Indeed, only a few "higher animals" have escaped from this by evolving language-like systems through which they can inform their descendants about accidents that happened to some of their ancestors' relatives.

[p185] Alan Watts 1960: "No one imagines that a symphony is supposed to improve in quality as it goes along, at that the whole object of playing it is to teach the finale. The point of music is discovered in every moment of playing and listening to it. It is the same, I feel, with the greater part of our lives, and if we are unduly absorbed in improving them we may forget altogether to live them."

[p206] Douglas Lenat 1997: "Analogy works because there is a lot of common causality in the world, common causes which lead to an overlap between two systems, between two phenomena or whatever. We, as human beings, can only observe a tiny bit of that overlap; a tiny bit of what is going on at this level of the world .... [So] whenever we find an overlap at this level, it is worth seeing if in fact there are additional overlap features, even though we do not understand the cause or causality behind it.

[p210] Decisiveness: We often speak of "making a choice," as though this were a deliberate act. However, that "action" may. in fact, be nothing more than the moment at which you stopped some process that was comparing alternatives-and then, by default, you simply adopted the one that was then at the top of some list. In such a case, a person may speak of using "free will"-but an observer could also see it as nothing more than a sort of admission (or even a boast) that one does not have a clear idea about what mental process produced that result.

[p239] Poincare 1913: "What is it indeed that gives us the feeling of elegance in a solution, in a demonstration? It is the harmony of the diverse parts, their symmetry, their happy balance; it is all that introduces order, all that gives unity, that permits us to see clearly and to comprehend at once both the ensemble and the details."

[p257] If you "understand" something in only one way, then you scarcely understand it at all-because when something goes wrong, you'll have no place to go. Bur if you represent something in several ways, then when one method fails, you can switch to another. Thar way, you can rum things around in your mind to see them from different points of view-until you find one that works for you!

[p271] As children, we not only learn particular things, but we also acquire new thinking techniques. However, no infant could ever invent, by itself, enough co develop an adult intelligence. So perhaps our most important skill is how we learn, not only from having our own experiences, but also from being told things by other people.

[p275] "The best way to have a good idea is to have lots of ideas." -- Linus Pauling

We admire our Einsteins, Shakespeares, and Beethovens-and many people insist that their accomplishments ate inspired by "gifts" that cannot be explained. If so, then machines could never do such things because (at least, in that popular view) no machine could hold any such mysteries.

However, when one has the fortune to meet one of those persons whom we portray as "great," one finds no single, unusual trait that seems to account for their excellence. Instead (at least it seems to me), all that we find are unusual combinations of otherwise common ingredients. I.

They are highly proficient in their fields. (But by itself we just call this expertise.)

They have more than usual self-confidence. (Hence better to withstand the scorn of peers.)

They often persist where others would quit. (But others may just call this stubbornness.)

They accumulate more Ways to Think. (But then they'll need better ways to switch.)

They habitually think in novel ways. (But so do others, albeit less frequently.)

They have better systems for self-control. (So they waste less time on irrelevant goals.)

[p278] This section has mainly aimed to explain why some people get better ideas than others do. But what if we change that question to ask, instead, what could make one person become less resourceful than another one? Here is one process that could tend to limit the growth of ones versatility:

The Investment Principle: If you know two different ways to achieve the same goal, you'll usually start with the method that you know best. Then, over time, that method may gain so much additional strength that you'll tend to use it exclusively---even if you have been told that the other technique is the better one.

[p328] For example, whenever something touches your hand, it seems to you that you instantly sense that you have felt a touch on your hand-and that this happened immediately, without any complex processing. Similarly, when you look at a color and sense that it's red, no intermediate steps seem to intervene-and so you can find nothing to say about it. Surely this is at least partly why so many philosophical thinkers conclude that there can be no "mechanical" explanation of why different stimuli seem each to have particular qualities: they simply have not worked hard enough to imagine adequate models of those processes; instead, they mainly attempted to show that no such models would ever be possible.