Try to delete the part or process.

Actively attempt to remove features or processes to reduce bloat and build things that are required, instead of adding things which prevent you from reaching the projects goals. Or as Musk says "if you don't run at tight margins, you're going to get nothing to orbit."

This principle originated from building spaceships but is generally applicable to building anything complicated.

Why

  • Build what you need - It is easy to add unnecessary features to solve problems because you can make arguments to rationalize every use case. Instead of attempting to make existing features cover the work.
  • It reduces complexity - A reduction in complexity means fewer chances of something going wrong, which is especially important if you're launching things into space 🚀
  • Ship faster - Running with fewer features means you reach your deadlines quicker.
  • Reduces bloat - Forcing an evaluation of a feature means you will ensure the feature is still valuable to you as the project progresses.

Article

The principle originated from Elon Musk, during his Starbase Tour: https://youtu.be/t705r8ICkRw?t=837

Here's the transcript:

"If you're not occasionally adding things back in 10% of the time, you're clearly not deleting enough."

"The bias tends to be very strongly towards let us add this part or the process step in case we need it."

"But you can basically make [just] in-case arguments for so many things. And for a rocket that is trying to be the first fully reusable rocket. - There's never been a fully reusable rocket. This is the holy grail of rocketry".

"So you really need to run at tight margins. Because if you don't run at tight margins, you're going to get nothing to orbit."

"So you've got to delete the part or process and you can't hedge your bets."

"That's why the grid fins, for example, do not fold down. Because that's a whole extra mechanism that we don't need. As long as the grid fins basically follow the flow, they are not really disturbing the flow. It's really neither here nor there. As long as they don't have a high angle of attack, it doesn't matter. "

"But in any case, it's the thing we could add later. So now these grid fins are humongous. We will go see them. But they're like, I mean, a dinosaur bear trap."

"And if you have a whole mechanism for folding them, that's clearly a part you don't need. So this is clearly a good design decision. That actually I didn't come up with, and it was like, great. But it followed the principle of delete the part, delete the process."

"I was like, great, good idea, let's not fold them. Why are we folding them anyway?"