First Principles

“I think it is important to reason from first principles rather than by analogy. The normal way we conduct our lives is we reason by analogy. [When reasoning by analogy] we are doing this because it’s like something else that was done or it is like what other people are doing — slight iterations on a theme.

First principles is kind of a physics way of looking at the world. You boil things down to the most fundamental truths and say, “What are we sure is true?” … and then reason up from there.

Elon Musk

In design, the first principles are the irreducible essence of a user's task or goal. It is not about the steps or the artifacts, but the user goal state. Usually, these will be short statements that seem somewhat obvious. If you cannot reduce a user task to first principles, then likely you don't understand the task.

Essential User Task

An essential user tasks tends to be simple (maybe even obvious), foundational and irreducible.

The first step to good design is to understand what the user needs to accomplish and why. Our favorite example is the programmable thermostat: for decades thermostats accreted features and behaviors: setpoints, programmability, connectedness, memory, battery backup and so on, but the user experience of them remained awful. In 2010 NestLabs deduced that the original designs all failed to grasp the essential user task: maintain situation-aware comfort when the user is at home, and to save power at all other times. Given this simple, clear essential user task, it becomes painfully obvious that features like setpoints and programs were artifacts the designers imposed on the user that did not directly address the user's core need.

Example essential user tasks:

I need to prepare to host 20 people at a backyard BBQ Saturday.

I need to launch 5,000 kilos into low Earth orbit.

This may seem simplistic, but when you pare back the goal to its irreducible version, you can see how anything the designer adds is really an artifact, and not the goal itself. Artifacts are the choices that service the goal. For a BBQ there are many questions and artifact that derive from the essential user task: Supplies? Instacart? Whole Foods? BevMo? Prep? Furniture? RSVPs? As user and design stories build, it should be possible to validate that each one directly services the essential user task. You can cut everything else.

It's important not to confuse these artifacts with the essential user task itself. The approach to addressing the essential user task will be different among designers, and that will result in a different set of artifacts, but each set, if it really services the essential task, should render a praiseworthy solution.