[josephg]

I have a funny relationship with this. I also come from a formal CS background too. The old joke is that there are two lies in Computer Science: firstly its not science, and secondly it isn't really about computers.

But the reality is, I still can't tell you what Computer Science actually is. Is it:

- About understanding how to control computers (which are fast electronic machines)

- About inventing programming, from the ground up. (A weird sub-discipline of mathematics and category theory)

or

- Learning to make software in order to improves the lives of humans

We sort of need to learn all three aspects. Haskell programs run slower than C++ programs because haskell isn't written in harmony with the physical CPU cores we've made. Making fast programs is pointless if our software doesn't solve user needs. And solving user needs are impossible if we can't express ourselves clearly to the computer - which programming language theorists are obsessed with.

I think the basics of hardware is part of CS, but maybe a CS undergraduate degree doesn't give anyone enough time to really go broad in the field. I dunno!

[zonotope]

> About understanding how to control computers (which are fast electronic machines)

Computer Systems Engineering

> About inventing programming, from the ground up. (A weird sub-discipline of mathematics and category theory)

Computer Science

> Learning to make software in order to improves the lives of humans

Software Engineering

[josephg]

I mean, I hear what you're saying - but all of those things also seem to be a single discipline.

Otherwise, where do operating systems fall? Are they systems engineering? They don't seem to be entirely about the hardware to me, and they were a core part of my CS program. What about SeL4 - which is a formally verified operating system project?

How about programming languages like C or Rust? Is that computer science, or systems engineering? How about Excel - the world's most popular programming language - that happens to be functional? Are financial planners doing computer science when they program a spreadsheet?

The lines are blurry everywhere. My CS program offered 3 different degrees, like you said - Computer engineering, Computer Science and Software Engineering. The only difference was the CS degree had a lot of electives, and the other two filled those electives in with (different) required subjects.

Maybe CS is just "lets play with some cool things on computers!". And there's a big playpen of things to explore. Thats more or less how it feels to me.

[saurik]

The lines between these majors definitely blur and some of the required courses do overlap; yet, they are still separate majors, the same way that the many specific sub-disciplines of biology are separate majors despite also having blurry overlap.

[linhvn]

Computer Science is not about learning to make software, although it is usually a byproduct, as strong understanding of fundamental allows you to design software correctly from the first principle. Programming; however, is usually done through training at work.

Computer Science is about understanding what computation can and cannot achieve, and more importantly, how to achieve it (that is where it differs from Mathematics, where mathematicians are usually not interested in the how part). Under this definition, we can put typical college subjects into consideration:

* Data Structures and Algorithms: about studying how to manipulate data to solve a task efficiently.

* Complexity Theory: about formal classification of hardness of problems. What makes a computational problem "hard" or "easy"?

* Computer System: about how to construct a software system to achieve certain purposes. What are the constraints in a system (performance, security, privacy, correctness, fault tolerance, etc), and how to design a system to address such constraints? What tradeoffs to be made when you cannot meet all the desired requirements?

* Distributed System: how to design system with a few to massive number of computers that are connected in a network? How do you reason about fault tolerance, consistency, sharding, and so on?

* Operating System: about how to create abstraction to the hardware, that allows for other softwares to interact with it without having to explicitly deal with the hardware?

The list could go on, but I just give a couple of examples.

[ihatepython]

- Learning to make software in order to improves the lives of humans

This is not a discipline that I am aware of

- Learning to make software in order to make the lives of humans miserable

This is a discipline, but not quite Computer Science

- Learning to make software so that great engineers become average engineers, and incompetent engineers become managers

This is software engineering

[jltsiren]

There is also the part of CS that could be described as the science of computation.

The lines between academic fields are primarily administrative. Their main purpose is to facilitate undergraduate education. They are also fuzzy and vary between institutions. A person working in a CS department could find their home in the mathematics department at another university. Or physics. Or economics. Or biology. Or somewhere else. No matter what CS was at your university, it can be something very different at another.