"There are only two hard things in Computer Science: cache invalidation and naming things" - Phil Karlton http://people.famouswhy.com/phil_karlton/ (NB: "hard" things)
While we're being flippant: Every problem in computer science can be solved by adding another level of indirection - except for the problem of too many levels of indirection
I don't think you read the article. It is only saying that there are two things you need to know in jest. If you looked at the article, you'd see that many fields, such as CS, have more than one set of "two things" that you need to know.
I will not comment on whether most fields can really be boiled down to just two notes, but you'll notice that the author states that one of the "things" about his rule of two things, is that everyone you ask will give you a different two. Since the multiple CS entries are all (I think) from different people, they do not violate the author's assertion.
The answers in the article are pretty cool, except for the programming ones. Just like in programming, people try to get cute with conciseness and end up making pretty unfunny jokes. Once you have heard the word "idiot" in anything having to do with programming, subsequent mentions are yawners.
But the whole idea of narrowing down everything to two core principles is awesome; so +1 from me, certainly.
The Two Things about Biology:
1. Evolution is the process through which genetic structures that are better equipped to reproduce viable copies will tend to proliferate.
2. Except for the Platypus.
Obviously the premise of "two things" is fairly ridiculous, but I bet it's an interesting thing to ask people at parties. I cannot stand party small talk, and the most fun I've had socialising with strangers were when I ask them straight questions like these.
Another thing I ask people, just out of curiosity since it's not insightful at the same level, is to just go through their average day. Sort of like a bottom-up description of their work/study/whatever live, instead of the top-down answer you get when you ask "so, what do you do".
Axiom of Choice has been on shaky ground for the past 50 years and really only continues it's existence through inertia. The second one has some deep wisdom in it though :)
While we're being flippant: Every problem in computer science can be solved by adding another level of indirection - except for the problem of too many levels of indirection