Neil Lyons

Freelance Web Developer based in the UK.

Reasoning from first principles

I watched an interview where Elon Musk talks about having a framework for thinking. Which he describes as “reasoning from first principles” with the opposite being “reasoning by analogy”.

Reasoning from first principles is about breaking the world around us down into fundamental truths and reasoning up from there.

Reasoning by analogy is about comparing things to how they have been in the past or other things which are similar and drawing similar conclusions.

The example Elon Musk uses is a battery pack. Historically they have been expensive. Reasoning by analogy would mean that this is how they will always be. Reasoning from first principles requires thinking. What are the costs associated with building a battery pack today and can this be improved upon? Which requires thinking about what are the raw materials? How much do they cost? What will the factory costs be? Labour costs? etc etc. You can see it requires a lot more mental energy.

Reasoning by analogy is definitely quicker and easier. You don't have time in day to day life to consider every decision from first principles. But it might be worth reconsidering some decisions/beliefs from first principles, to see if a better decision can be made or a better perspective can be gained.

It is an interesting topic to think about. I think it also explains our tendency as humans at being too quick to judge, stereotypes, and people being stuck in their ways.

After writing this I discovered a really well written article about first principles which goes into a lot more detail