The document discusses the concepts of incrementalism and marginalism. It provides 3 key points:
1) Incrementalism refers to implementing changes gradually through many small incremental steps, while marginalism uses marginal concepts in economic theory related to small changes in quantity.
2) The main difference is that incrementalism focuses on gradual implementation through many small changes over time, whereas marginalism analyzes the impact of small changes in quantity on other economic variables like revenue, cost, and profit.
3) Price elasticity is then defined as a measure of how responsive quantity demanded is to changes in price, and the determinants of price elasticity like availability of substitutes are explained.