Your question here was one of the biggest open questions in political economy (now just economics) in the early 20th century. It motivates the modern foundation of the field, and earned itself the moniker the marginal revolution https://en.m.wikipedia.org/wiki/Marginal_Revolution
It resulted in an explosion of theoretical and empirical literature in microeconomics, and in many ways creates the field we know today.
It resulted in an explosion of theoretical and empirical literature in microeconomics, and in many ways creates the field we know today.