Abstraction Layers

Instructional Material

• [optional] Taboo Your Words
• [optional] Replace the Symbol with the Substance
• [optional] Abstraction Layers in Programming

Replacing the Symbol with Substance [35 minutes]

In software, an abstraction layer refers to the way that you can "abstract away" complexity in a system. For example, you, the user, don't need to know how silicon chips work in order to read this text. The vast complexity of your computer is almost entirely hidden away, out of sight, and all you have to do is "open" a "web" "page". Most of the time, it's okay to just open the web page and not worry about the underlying complexity — until someone unplugs your ethernet cable.

Abstraction layers aren't just a software thing, though. Our minds are designed to manage the dizzyingly complex system of reality and we use abstraction layers as a matter of habit. Neurological circuits automatically stitch together messy sensory inputs, allowing us to see objects as continuously solid, identify their edges, and spot their motion —

— or to perceive them as "objects" at all. On one abstraction level, a chair is a piece of furniture for sitting in. Drop down a level and it's a series of wooden sticks held together with nails. Drop down another, and it's a series of wooden sticks coated in a highly flammable substance. If you're a guest at a friend's house, you want layer one. If you're trying to repair a broken chair, you want layer two. And if you're freezing to death in a blizzard, you want layer three.

A good heuristic for identifying when you need to change your abstraction level is when you find yourself unable to devise a solution to a question or when you witness something that you know is impossible. Harry's list of unusual ways to kill someone is a prime example of shifting to a lower abstraction level when a higher one proves unsuitable.

Identifying Abstractions [10 minutes]

The world around us is full of abstractions. Work with your cohort to come up with a list of the ways in which you simplify complexity into easy-to-think-about abstractions. Try to avoid abstractions related to computers, and try to list at least fifty ways.

Example.

Three computer abstractions (which don't count, because computers are so crammed with these that it's too easy):

• "Opening" a webpage is an abstraction layer around internet packets. Packets are in turn built on top of http requests, which are built on ip, etc.
• A phone is an easy-to-use interface wrapped around a staggeringly complex artifact, which no single person knows how to build.
• Your browser's omnibar is an abstraction around the enormous complexity of indexing and analyzing the entire internet.

Three abstractions about the material world, which would count:

• A mechanical lock is a complex machine that can be reduced to two operations: "lock" and "unlock". But if you can drop down a few levels, you can do something impossible from the lock/unlock layer (picking the lock).
• A water faucet distills the complexity of plumbing, sanitizing, and water sourcing into an abstraction with two operations: "turn on" and "turn off".
• A person is an abstraction on top of a hideously complicated intelligence. Using the abstraction lets us make a number of assumptions about their behavior without needing to know the details of that specific entity's mind.

Going Down [20 minutes]

Each of the boxes below contains a scenario written at a high abstraction level. Read the scenario, and then try to drop to a lower level and describe what's going on. Come up with the best description you can as a cohort, and then hover over the answer box to see how you did. Your exact answer will differ — the important thing is to check if you had gone down the ladder far enough, rather than the specifics. (This is an inherently subjective exercise, but do your best.)

Spend five minutes per scenario. If you find yourself stuck, choose a word in your description and expand it.

Example. Suppose that the scenario is a game of baseball.

Then, you might come up with the description of an artificial group conflict in which you use a long wooden cylinder to whack a thrown spheroid, and then run between four safe positions.

Scenario 1. Two people playing the endgame of a nail-biting chess match.

Scenario 2. A person sitting on a bench and drawing on their tablet.

Scenario 3. A person talking to their friends on Discord.

Scenario 4. A delicious pot of stew cooking on the stove.

Break [10 minutes]

Take a ten-minute break.

Rationalist Taboo [45 minutes]

Now that you have a bit of practice at going down in the abstraction ladder, it's time to try a slightly harder version of the previous exercise.

The technique of rationalist taboo is describing a concept without using the concept's word, phrase, or any of its synonyms. In other words, rationalist taboo is an applied version of the previous exercise — except, rather than an artificial scenario, you have to drop down the abstraction ladder during a live conversation, about a concept that's deeply embedded in your map of reality.

Albert: "A tree falling in a deserted forest makes a sound."

Barry: "A tree falling in a deserted forest does not make a sound."

Clearly, since one says "sound" and one says "not sound", we must have a contradiction, right? But suppose that they both dereference their pointers before speaking:

Albert: "A tree falling in a deserted forest matches [membership test: this event generates acoustic vibrations]."

Barry: "A tree falling in a deserted forest does not match [membership test: this event generates auditory experiences]."

Now there is no longer an apparent collision—all they had to do was prohibit themselves from using the word sound. If "acoustic vibrations" came into dispute, we would just play Taboo again and say "pressure waves in a material medium"; if necessary we would play Taboo again on the word "wave" and replace it with the wave equation. (Play Taboo on "auditory experience" and you get "That form of sensory processing, within the human brain, which takes as input a linear time series of frequency mixes...")

— Taboo Your Words, by Eliezer Yudkowsky

Instructions [30 minutes]

Take turns going around the cohort.

Choose one of the concepts from the list below. Your job is to describe the concept without using the concept's name or banned words. You are also not allowed to use synonyms, acronyms, conjugates, etc of the name and the banned words. Err on the side of avoiding too many words, to make the game more engaging.

You win if you can get your cohort to name the concept (synonyms etc don't count). This is a back-and-forth conversation, so don't worry about getting the initial description perfect.

Once your concept has been named, move to the next member of your cohort. Start over with the first member once everyone has gone (each concept will probably only take a minute or two to name, so everyone is likely to go multiple times.)

Example. If you chose the concept Bayes Theorem, then you would avoid saying statistic, reverend, update, prior, posterior, or probability. (As well as their synonyms, acronyms, conjugates, etc.)

You might describe the concept as "A mathematical equation used to make predictions about the world's state. Each time an event occurs, you can use this equation to calculate how likely it is that the world is shaped a certain way."

List taken from Screwtape's version of the game.