The Privatization of Roads and Highways - Ludwig von Mises Institute

Public Goods and Externalities: The Case of Roads 133
to know it by simply asking him. Both, however, are incorrect.
The latter, the questionnaire method, may easily be dismissed.
The empirical unreliability of questionnaires and public opinion
polls alone should give us pause for thought. Furthermore, the
fact that people lie clearly invalidates this method as a good
foundation for scientific economics.
It might be argued nevertheless that the individual himself
surely knows his own preferences by introspection. Our answer,
once again, is no. The evidence of impulsive buying is overwhelming.
How many of us have walked down the street with
nothing further from our minds than the purchase of an ice
cream cone, only to find ourselves, seemingly without any conscious
volition, plunging hand into pocket, relinquishing the
required sum, and avidly eating away? Is it that we “really” or
“unconsciously” were thinking of ice cream? While that could be
true, it need not be. Regardless, however, of the exact psychological
mechanics involved, it is clear that, before the purchase,
introspection might well have failed to reveal the hidden desire.
We must therefore conclude that, in at least some cases, the individual
economic actor may not know his own value scales. Motivational
advertising, to the extent that it is efficacious, is further
evidence of the fact that introspection will not necessarily dredge
up the true preferences of the individual. The buyer may think he
knows what he wants, but in reality, according to this argument,
some of his tastes are at the beck and call of Madison Avenue,
and not amenable to his own consciousness.
If true value-rankings can be scientifically discovered neither
by introspection nor by questionnaire surveys, how can they be?
The answer is through market purchases and sales, or more generally,
through observation of human action. Ludwig von Mises
expressed this idea as follows:
It is customary to say that acting man has a scale of wants or
values in his mind when he arranges his actions. On the basis
of such a scale he satisfies what is of higher value, i.e., his more
urgent wants, and leaves unsatisfied what is of lower value,
i.e., what is a less urgent want. There is no objection to such a