Reasoning from First Principles

Reasoning from First Principles

Reasoning from First Principles rather than from analogy is important for new breakthroughs according to legendary businessman Elon Musk. He says most people conduct their lives by reasoning from analogy. We see someone else doing something and we copy; even if we give it a slight iteration on the theme. 

Why? Because it’s mentally easier to reason by analogy than from First Principles.

First Principles is a way of looking at the world by boiling things down to the most fundamental truths. Figure out what you know is true, or are reasonably sure is true, and then reason up from there. This takes a lot more mental energy.

Elon uses battery packs as an example. You might say battery packs are really expensive and that’s just the way it is, and that’s just the way it will always be. If you apply this analogous reasoning you’ll never be able to get to the next new thing. 

Historically batteries cost about $600 per kilowatt hour. You might assume it’s not going to get much better than that. Reasoning from First Principles you’d ask what are batteries made from? What are some of the material constituents of the batteries? Cobalt, nickel, aluminum. Add some carbon and some polymers for separation, and steel. Break it down to its basic components. What would each of those things cost if you bought them on the London Metal Exchange? What is the spot market value? 

You’ll discover the actual cost is $80 per kilowatt hour. Next you think of clever ways to take the materials and combine them into a battery cell. You end up with batteries that are cheaper than anyone realizes. And that is the power of reasoning from First Principles.