Jimmy Gill, and his brother W. W. "Doc" Gill lived across the street from my grandmother's house. Jimmy framed pictures, Doc was a dentist. One summer, very long ago, my dad and I were outside the house when Doc — a very old man at the time — came shuffling up the sidewalk. Dad asked, "Why don't you let Doc look at your loose tooth?" Of course I didn't want him too. But dad and Doc convinced me to open my mouth and, before I could react, Doc snaked his gnarly old forefinger into my mouth and the tooth was out. That should have been the beginning of a deep-seated mistrust of doctors, but my dad and Doc knew what they were doing. The tooth was out and the extraction didn't hurt. But how times have changed. Today an ungloved hand wouldn't go near a patients mouth.

The second article features Orr's reflections on his book. The third article recounts a Yankee gunboat on the Red River during the war of Northern aggression. The links go to digitized versions of the articles; the page titles link to the scan of the article.

These shapes of these objects are arbitrary and were chosen so as not to represent something that might have meaning due to familiarity. While they have rotational symmetry, this is for convenience for something that is not related to the problem of mental privacy.

Next, let us build a physical device that takes two of these objects as input and selects one for output. Parenthesis will be used to group the inputs and an arrow will terminate with the selected output. The device will operate according to these four rules:

A network of these devices can be built such that the output of one device can be used as input to another device.

It is physically impossible to tell whether this device is acting as a NAND gate or as a NOR gate. We are taught that a NAND gate maps (T T)→F, (T F)→T, (F T)→T, and (F F)→T; (1 1)→0, (1 0)→1, (0 1)→1, (0 0)→0 and that a NOR gate maps (T T)→F, (T F)→F, (F T)→F, (F F)→T; (1 1)→0, (1 0)→0, (0 1)→0, (0 0)→1. But these traditional mappings obscure the fact that the symbols are arbitrary. The only thing that matters is the behavior of the symbols in a device and the network constructed from the devices. Because you cannot tell via external inspection what the device is doing you cannot tell via external inspection what the network of devices is doing. All an external observer sees is the passage of arbitrary objects through a network.¹

But NAND and NOR gates are universal logic gates which can be used to construct a "universal" computing device.²

So we can construct a device which can respond to the question "what logic gate was used in your construction?"

Depending on how it was constructed, its response might be:

1. "I am made of NAND gates."
2. "I am made of NOR gates."
3. "I am made of NAND and NOR gates. My designer wasn't consistent throughout."
4. "I don't know."
5. "What's a logic gate?"
6. "For the answer, deposit 500 bitcoin in my wallet."