Question

Different Indifference Curves Should Not Cross: If the weak prefer- ence ordering is “rational”, then indifference curves cannot cross (or, more generally, indifference sets cannot intersect). In some undergraduate presen- tations of a result along these lines1, either monotonicity or strong mono- tonicity (some form of “more is preferred to less” property) is also assumed. The reason for this is, presumably, that it simplifies the explanation of the result. Nonetheless, from a theoretical perspective, this approach is unde- sirable because it involves making a superfluous assumption. Attempt to establish the validity of this result without assuming anything other than the “rationality” of the weak preference ordering.

Answer 1

Let me answer the question in the following way.

Indifference Curve

An indifference curve is a downward sloping curve that shows various combinations of two goods that yield the same level of utility to the consumer.

Why two indifference curves doesn't intersect each other?

If two indifference curve intersects each other, we will get a contradictory result in terms of preference ranking. This is actually because at the point of tangency, the higher curve will give as much as of the two commodities as is given by the lower indifference curve. It is an absurd and impossible situation. At the same time, consumer is rational and he will always try to maximise his benefits or satisfaction.