Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: A brief history of computers, published by Adam Zerner on July 19, 2023 on LessWrong.

Recently I've been learning about the history of computers. I find it to be incredibly interesting. I'd like to write a post about it to summarize and comment on what I've learned.

I'm a little hesitant though. I'm no expert on this stuff. I'm largely learning about it all for the first time. So then, take all of this with a grain of salt. It's more of a conversation starter than a finished product. If you want something authoritative, I'd recommend the Stanford Encyclopedia of Philosophy.

Logic

Let's start with logic. Computers are largely based on boolean logic. Y'know, 1s and 0s. AND, OR, NOT. George Boole did a bunch of important work here in the mid 1800s, but let's try backing up even further. Was there anything important that came before Boolean logic?

Yeah, there was. It goes all the way back to Aristotle in ~350 BCE. Aristotle did a bunch of groundbreaking work in the field of logic. Furthermore, after "breaking the ground", there weren't any significant developments until the mid 1800s. Wow! That's a long time. An unusually long time. In other fields like mathematics, natural sciences, literature and engineering, there were significant advances. I wonder why things in the field of logic were so quiet.

Anyway, let's talk about what exactly Aristotle did. In short, he looked at arguments in the abstract. It's one thing to say that:

Filo is a dog

Therefore, Filo has feet

It's another thing to say that:

R is a P

Therefore, R has Q

The former is concrete. It's talking about dogs, feet and Filo. The latter is abstract. It's talking about P's, Q's and R's. Do you see the difference?

Before Aristotle, people never thought about this stuff in terms of P's and Q's. They just thought about dogs and feet. Thinking about P's and Q's totally opened things up. Pretty cool. Abstraction is powerful. I think this is very much worth noting as an important milestone in the history of computers.

Ok. So once Aristotle opened the flood gates with categorical logic, over time, people kinda piggybacked off of it and extended his work. For example, the Stoics did a bunch of work with propositional logic.

Propositional logic is different from categorical logic. Categorical logic is about what categories things belong to. For example, earlier we basically said that dogs belong to the category of "things with feet" and that Filo belongs to the category of "dogs". With those two statements, we deduced that Filo must also belong to the category of "things with feet". It makes a lot of sense when you think about it visually:

On the other hand, propositional logic is about things being true or false. For example, with this:

I don't have an umbrella

we can deduce things like:

"It is raining or I have an umbrella" is true

Propositional logic is about truth and uses operators like AND, OR, NOT, IF-THEN, and IF-AND-ONLY-IF. Categorical logic is about categories and uses operators like ALL, NO and SOME.

After propositional logic, subsequent work was done. For example, predicate logic kinda piggybacked off of propositional logic. But in general, nothing too crazy was going on. Let's jump ahead to the mid 1800s and George Boole.

Boole introduced stuff like this:

(p and q) is false

(p or q) is true

(not (p and q)) is true

But wait a minute. I'm confused. Didn't we get that sort of thing from propositional logic all the way back in 300 BCE from the Stoics? In researching this question I'm seeing things saying that it did in fact already exist, it's just that Boole made it more "systematic and formalized". I don't understand though. In what way did he made it more systematic and formalized?

Oh well. Suffice it to say that boolean logic was a thing that we knew about. Let's move on.

Jacquard loom

I was going to star...