Concept Notes 1: Market Fundamentals & The Law of Demand
1. What is a Market?
In economics, a market is not restricted to a geographical location (like Chandni Chowk or Crawford Market). A market is an institutional mechanism or arrangement that facilitates direct or indirect contact between buyers and sellers to negotiate price and exchange goods and services (e.g., e-commerce platforms, stock exchanges, commodity wholesale mandis).
2. The Law of Demand & Ceteris Paribus
- The Law of Demand: Holding all other factors constant (ceteris paribus), there exists an inverse relationship between the price of a commodity and its quantity demanded:
$$P \uparrow \implies Q_d \downarrow \quad \text{and} \quad P \downarrow \implies Q_d \uparrow$$
- Ceteris Paribus Assumptions (Other Things Held Constant):
- Income of the consumer remains unchanged.
- Tastes, preferences, and fashions remain constant.
- Prices of related goods (substitutes and complements) remain unchanged.
- No expectation of future price alterations.
[ THE LAW OF DEMAND ]
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[ REASONS FOR DOWNWARD SLOPE ] [ SHIFTS VS MOVEMENTS ]
1. Law of Diminishing Marginal Utility - Movement along curve:
(Each extra unit gives lower satisfaction) Caused solely by OWN PRICE change
2. Income Effect (Expansion / Contraction)
(Lower price increases real purchasing power) - Shift of entire curve:
3. Substitution Effect Caused by non-price factors: income,
(Lower price makes good cheaper than substitutes) tastes, population, related goods
3. Movements Along vs Shifts in Demand Curve
| Type of Change | Primary Causal Factor | Graphical Manifestation | Terminology |
|---|---|---|---|
| Change in Quantity Demanded | Change in Own Price of the commodity ($P_x$) | Movement along the same existing demand curve | Price drops $\rightarrow$ Expansion (Extension)<br>Price rises $\rightarrow$ Contraction |
| Change in Demand | Non-price determinants (Income, Tastes, Price of Substitutes/Complements) | Complete bodily shift of the demand curve | Favorable shift $\rightarrow$ Rightward Shift (Increase)<br>Unfavorable shift $\rightarrow$ Leftward Shift (Decrease) |