Why is the bliss point utility function convex even though it has concave portions to it ?

According to Nicholson and Snyder (authors of Microeconomic theory - Basic principles and extensions) a function has diminishing MRS and is convex only if it is quasi-concave. Accordingly, I checked quasi concavity for the bliss point utility function $U (x, y) = 12x + 16y –x^2 – y^2$, and it showed that the function is quasi concave throughout. This means that the function should be convex throughout, but that is not the case here.

  • $\begingroup$ @denesp Where are you for this one? $\endgroup$
    – EconJohn
    Jan 5, 2018 at 5:50
  • $\begingroup$ @EconJohn One does not get notifications if tagged in a question where one has no posts. I am also unsure what you mean? I am not the single arbiter of truth. $\endgroup$
    – Giskard
    Jan 5, 2018 at 11:16
  • $\begingroup$ @denesp whoops, Didn't know that. In the past you seemed to be knowledgeable on bliss points i.e. economics.stackexchange.com/questions/13782/… $\endgroup$
    – EconJohn
    Jan 5, 2018 at 21:17

1 Answer 1


Quasi-concave utility functions represent convex preferences. But that preferences are convex means that the weakly-better sets are convex, it is not about the convexity of any function.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.