Charles Petzold

Babies Are Illogical: The “Lost” “Chapter” of “Code”

May 28, 2008
New York, N.Y.

I recently discussed how I cut some pages from my 1999 book Code: The Hidden Language of Computer Hardware and Software in a futile attempt to get the page count down. Those pages focused on some logic puzzles of the Victorian author beloved by geeks worldwide: the Rev. Charles Dodgson, a.k.a. Lewis Carroll.

Yesterday evening I rummaged around in my attic — actually I did the New York City equivalent, which involved visiting the Manhattan Mini Storage building on Spring and Varick — and found the box in which in the summer of 1999 I dumped all the existing printed and hand-written pages of Code and some magnetic media. The magnetic media turned out to be four 100-megabyte Zip disks, and fortunately we still own a Zip drive with a USB cable, and fortunately the disks were still readable. (It's only been nine years. I suspect the magnetic-media-anxiety-factor is much worse at the 20-year time period.)

Here's the original beginning of Chapter 10:

10. Babies Are Illogical

I replaced this all with the sentences "What is truth? Aristotle thought that logic had something to do with it. The collection of his teachings known as the Organon (which dates from the fourth century B.C.E.) is the earlier extensive writing on the subject of logic....

Later in the chapter (equivalent to page 92 of the printed book) I deleted the following after discussing the "All men are mortal..." syllogism:

The words sorites is Greek for "heap" and refers here to a heap of syllogisms. There is also a "sorites paradox" that involves a real heap of grain. Take one grain out and you still have a heap. By induction, you can continue removing grains and it still remains a heap even when no grains are left.

Boolean logic is a logic of classes. You can also solve sorites using predicates and implication. While working on Chapter 12 ("Logic and Computability") of my forthcoming book The Annotated Turing: A Guided Tour through Alan Turing's Historic Paper on Computability and the Turing Machine I tried to get Lewis Carroll involved once again. This is a rather sketchy passage from an early draft of Chapter 12:

Google Book Search has a copy of Symbolic Logic, and the book was also republished by Dover. The sample sorites begin on page 112, but be forewarned that some of the puzzles in this book are anti-Semitic and rascist, which comes as a shock even if you're accustomed to reading Victorian literature.

Although Symbolic Logic says "Part I. Elementary" on its title page, Carroll did not live to publish subsequent parts. The book Symbolic Logic, edited with annotations and an introduction by William Warren Bartley, III (Harvester Press, 1977) has a recreation of the uncompleted and long-lost Part II.