What does “mathematically incorrect” mean? The role of the utility function in EUT is to represent the agents preferences. Preferences can be rational (i.e. c

What does “mathematically incorrect” mean? The role of the utility function in EUT is to represent the agents preferences. Preferences can be rational (i.e. consistent) and not be represented by the logarithm of wealth. If Mr. X has some amount to invest now to pay for his child’s college in five years it’s not “irrational” to opt for something less risky than taking a loan to get a leveraged equity investment. Mr. X may not care that his portfolio wouldn’t growth at the optimal highest possible rate if left untouched forever, if that’s what you mean by “mathematically incorrect result”. Mr. X doesn’t care about your idea of “correct result”, he cares about being reasonably certain to have enough money available in five years. Now, you tell me to use the maths from EE to find the “correct” utility functions. How can I use the maths from EE to select a portfolio if I want to take out a certain amount of money in five years?