The opening line that "The work of engineers used to be about taking small parts that they understood entirely and using simple techniques to compose them into

The opening line that "The work of engineers used to be about taking small parts that they understood entirely and using simple techniques to compose them into larger things that do what they want" is not correct. Emergent behaviour has always been an issue for complex system. Just look at the story behind the Tacoma Narrows Bridge. Computing is extremely complex, so the issue is probably more acute, but it is not unique.