In my reading of Gödel, Escher, Bach, one of the big themes is the emergent nature of intelligence. Watch how Hofstadter sets this up in his first discussion of the question of intelligence:

No one knows where the borderline between non-intelligent behavior and intelligent behavior lies; in fact, to suggest that a sharp borderline exists is probably silly. But essential abilities for intelligence are certainly:

to respond to situations very flexibly;

to take advantage of fortuitous circumstances;

to make sense out of ambiguous or contradictory messages;

to recognize the relative importance of different elements of a situation;

to find similarities between situations despite differences which may separate them;

to draw distinctions between situations despite similarities may link them;

to synthesize new concepts by taking old them together in new ways; to come up with ideas which are novel.

Here one runs up against a seeming paradox. Computers by their very nature are the most inflexible, desireless, rule-following of beasts. Fast though they may be, they are nonetheless the epitome of unconsciousness. How, then, can intelligent behavior be programmed? Isn’t this the most blatant of contradictions in terms? One of the major theses of this book is that it is not a contradiction at all. One of the major purposes of this book is to urge each reader to confront the apparent contradiction head on, to savor it, to turn it over, to take it apart, to wallow in it, so that in the end the reader might emerge with new insights into the seemingly unbreathable gulf between the formal and the informal, the animate and the inanimate, the flexible and the inflexible.

How do rigidly programmed behaviors become more than the sum of their parts? Check out this unbelievably good RadioLab episode about emergence.