The best way to refine an idea is to make something.
Build a demo of the feature you’ve been thinking about. Sketch a storyboard for the scene you want to film. Write the new song you've been humming.
When you make something, you create clarity. You move a conversation from the abstract to the concrete. You spend your energy on real problems, not imagined ones.
Apple does this when they build new products.
Ken Kocienda, an engineer on the original iPhone team, wrote:
Demos were fundamental to our work at Apple. We used them to highlight the potential, explore the concepts, show the progress, prompt the discussion, and drive the decisions for making our products.
Demos were a company-wide ritual at Apple, with Steve Jobs deeply involved. He’d offer his exacting opinions on seemingly minute product details, down to the individual interactions on the keyboard.
Something similar was also true of how Apple built the hardware for the iPhone. They tested out, and later invented, countless new materials to get to an experience they were satisfied with.
They didn’t spend time writing down a set of product principles that would guide them. Instead, according to Kocienda, they let their approach “flow from the work.”
The process of making something reveals what you really believe.
When you make stuff, you also figure out if your ideas are any good to begin with. It wasn't until the Wright Brothers tried to fly their first glider that they realized the accepted aerodynamic theories and equations of their day were wrong.
It's too easy to weasel out of important details when you let your ideas stay locked in your head. Reality has a surprising amount of detail!
When you try to explain or clarify an idea, words can only get you so far.
To get the rest of the way, make something.
Related: I've always loved this video of Pharrell discovering Maggie Rogers. They spend the first couple minutes discussing her background, but it isn't until he hears her music that he fully grasps what makes her special.