and Therefore, along an indifference curve, These examples might be useful for modelling individual or aggregate demand. Biology As used in biology, the indifference curve is a model for how animals 'decide' whether to perform a particular behavior, based on changes in two variables which can increase in intensity, one along the x-axis and the other along the y-axis. For example, the x-axis may measure the quantity of food available while the y-axis measures the risk involved in obtaining it. The indifference curve is drawn to predict the animal's behavior at various levels of risk and food availability. Criticisms Indifference curves inherit the criticisms directed at utility more generally. Herbert Hovenkamp (1991) has argued that the presence of an endowment effect has significant implications for law and economics, particularly in regard to welfare economics. He argues that the presence of an endowment effect indicates that a person has no indifference curve (see however Hanemann, 1991) rendering the neoclassical tools of welfare analysis useless, concluding that courts should instead use WTA as a measure of value. Fischel (1995) however, raises the counterpoint that using WTA as a measure of value would deter the development of a nation's infrastructure and economic growth. Austrian economist Murray Rothbard criticised the indifference curve as "never by definition exhibited in action, in actual exchanges, and is therefore unknowable and objectively meaningless." See also Budget constraint Community indifference curve Consumer theory Convex preferences Endowment effect Level curve Microeconomics Rationality Substitute good Utility–possibility frontier Notes References Further reading External links Anatomy of Cobb–Douglas Type Utility Functions in 3D Anatomy of CES Type Utility Functions in 3D Family economics Economics curves Utility 1881 in economics