At some point Frank Knight stated that the economic agent (humans)
do not have a fixed set of preferences (goals, values) the achievement
of which  they set out to maximize with logical rigour (consistently and
fully).  Rather they spend their lives searching for values.  That is, their
preferences never come  to a stable equilibrium on the basis of which
utility (achievement) can be maximized.

      Of course these are not his words.

      Where did he say it?

Robin Neill