Amazon Principle Engineer Review

In Amazon, if a feature spans multiple systems and teams; it usually requires a review from a Principal Engineer (PE review).

In one of the internal talks, a Principal Engineer (PE) shared a simple technique they employ to drive the PE review. It was to repeatedly ask "why" like a five year old.

For example the conversation in a PE review can go something like this:

Engineer: We're creating a system to duplicate an item in different marketplaces.

PE: Why?

Engineer: To allow customers to buy the same item in different marketplaces.

PE: Why does it have to be duplicated for that to happen?

Engineer: Because each marketplace has a separate catalog

PE: Why is it separate?

And so on...

This technique forces the engineers to dig deeper into their own design and question the foundations on which it is built.

It is possible we're treating the symptoms of an issue instead of addressing the root cause and by repeatedly asking "why", we may expose some assumptions we've made or issues we did not consider in our initial design.

Good thing about this technique is that you don't have to be a Principal Engineer to use it. Even if we're fresh out of college, we can ask "why" in a design meeting. If it doesn't uncover anything new, it will at least help us understand the system deeply.

“Millions saw the apple fall, Newton was the only one who asked why?” - Bernard M. Baruch