Indifference maps and their features

An indifference map is a family of indifference curves, each showing a different level of satisfaction.

We assume monotonic preferences: the consumer prefers a bundle with more of at least one good and no less of the other. For example, (5, 8) is preferred to (5, 7) and to (4, 8).

From this follow the features of indifference curves:

• They slope downward from left to right. If one bundle has more of one good, it must have less of the other to give the same satisfaction.
• A higher curve gives higher utility. A curve further from the origin contains bundles with more goods, so they are preferred.
• Two indifference curves never intersect. If they did, the crossing point would be equal to bundles on both curves, which would make two unequal bundles equally good. That is impossible.

Example: with monotonic preferences, (6, 6) > (6, 5) > (5, 5): the first has more of good 2 than the second, and the second has more of good 1 than the third.