Most of us reason by analogy most of the time: "This worked before, it will work again." "We're the Uber of laundry." "I'll do what my competitor does." This borrowed thinking is efficient but often wrong.

Elon Musk famously distinguished first principles from analogical reasoning: "Through most of our life, we get through life by reasoning by analogy, which essentially means copying what other people do with slight variations. [First principles] allows you to cut through the fog and see what is actually possible."

The danger of analogy is that it borrows assumptions from other contexts without examining whether they apply. In this topic, you will learn to recognize when you are reasoning by analogy, evaluate whether the analogy is valid, and escape to first principles when it is not.