It's been 17 years since I started working in my 1st real job. It was in a bank and it was introduction week. There were 50 other students in the same situation as I and we were all sitting in an awe inspiring room full of ornaments. We were waiting for the next speaker. An elderly man entered the stage. The experience of decades could be seen in the wrinkles in his face. And I will never forget what he told us:

No matter what kind of business department you will work in, always remember that it's all about ledgers.

So this old banker's mental model was the ledger. Actually he was using the T account representation of a ledger in his presentation. And he explained, that no matter what kind of financial business he was working on, he always transferred it on ledgers in his mind. Retail credit, cash transfer, trade finance, lending, money market, funding, ... you name it. By applying all problems on ledgers he could easily understand the business of each and every department in the bank.

Are there Mental Models in IT?

After reading James Clear's article about mental models (and Richard Feynman) I asked myself what mental models we have in IT. What abstractions can we use to reason about any kind of problem we're confronted with? Whenever I reason about a new system I instantly think about its data modelling, so I guess these 2 might qualify as mental models in IT:

• Entity Relationships (ER)
• Object Oriented Programming (OOP)

Are design patterns a mental model? I don't think so. Each pattern suits a special problem, so a pattern is by far not generic enough to work as a mental model. And what about the sum of all patterns? No, I think trying to find patterns is just human behaviour.

What about Functional Programming (FP)? Since I'm not proficient in FP I don't know if it can work as a mental model. Does it?