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Chapter 2 A Theory of Preferences. Theory of Preferences is based on three ideas regarding individuals:. They have consistent preferences. They seek to maximize preferences. They are willing to make tradeoffs between different goods. Completeness Assumption:.
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Theory of Preferences is based on three ideas regarding individuals: • They have consistent preferences. • They seek to maximize preferences. • They are willing to make tradeoffs between different goods.
Completeness Assumption: • Given any two bundles, one of the following is true: - Bundle 1 is preferred to bundle 2 - Bundle 2 is preferred to bundle 1 - Bundle 1 is indifferent to bundle2
Transitivity Assumption: • Given any three bundles: - If bundle 1 is at least as good as bundle 2 and bundle 2 is at least as good as bundle 3, then bundle 1 is at least as good as bundle 3.
Non-satiation Assumption: • Given any two bundles, if bundle 1 contains more of one good than bundle 2, and it does not contain less of the other good, then bundle 1 is preferred to bundle 2.
Maximization Assumption: • Individuals always make choices that leave them better off.
Continuity Assumption • Through any consumption bundle in which the quantity of at least one good is positive, there is a continuous indifference curve.
Marginal Rate of Substitution • The marginal rate of substitution (MRS) is the rate at which someone is willing to trade-off one good for another while maintaining the same level of satisfaction. • More precisely, the marginal rate of substitution of good 2 for good 1 at any point (X1,X2), denoted as MRS (X1,X2), is the absolute value of the slope of the indifference curve at that point. (See Figure 2.7).
Diminishing Marginal Rate of Substitution • Note that in Figure 2.7 the MRS diminishes in a movement down the indifference curve. • A person whose preferences are shown in Figure 2.7 is less willing to substitute good 2 for good 1 at point B than at point A.
Figure 2.9 Different preferences and different indifference curves