First principles thinking requires you to dig deeper and deeper until you are left with only the foundational truths of a situation. Why this is needed? This is needed because different solutions present themselves at different layers of abstraction. This is the “art of reductionism“.
So how do we do this?
Just follow the Feynman technique, and four simple steps:
1. Pick and study a topic.
2. Take out a blank sheet of paper and write at the top the subject you want to learn. Write out what you know about the subject as if you were teaching it to someone who is unfamiliar with the topic—and not your smart adult friend but rather a ten-year-old child who can understand only basic concepts and relationships.
3. When you must use simple language that a child can understand, you force yourself to understand the concept at a deeper level and to simplify relationships and connections among ideas. If you struggle, you have a clear understanding of where you have gaps in knowledge. This is valuable feedback, because you have now discovered the edge of your mental capabilities. Knowing the limits of your knowledge is the dawning of wisdom.
4. Return to the source material, and then reread and relearn it. Repeat step 2 and compile information that will help you fill in those gaps in your understanding that you identified in step 3. Review and simplify further as necessary.