How can fallible creatures like us (claim to) know something? The scientific method is about answering that question well. To answer the question well, we have made at least three big innovations:
1. Empiricism. But no privileged observer. What you observe should be reproducible by all others.
2. Open to criticism: If you are not convinced about the method of observation, the claims being made, criticize. Offer reason or proof.
3. Mathematical Foundations: Reliance on math or formal logic to deduce what claims can be made if certain conditions are met.
These innovations along with two more innovations have allowed us to ‘scale.’ Foremost among the innovations that allow us to scale is our ability to work together. And our ability to preserve information on stone, paper, electrons, allows us to collaborate with and build on the work done by people who are now dead. The same principle that allows us to build as gargantuan a structure as the Hoover Dam and entire cities allows us to learn about complex phenomenon. And that takes us to the final principle of science.