The advocates of the sunk cost fallacy state that, since an agent ponders in his decisions marginal costs against marginal incomes, any consideration upon sunk costs would be irrational. Notwithstanding, as soon as we accept the arguments of the said sunk cost fallacy and try to put its recommendations into practice, we discover that we have just become an easy prey of a more severe kind of irrationality: the one that concerns with intransitive preferences.

Jon Elster exemplifies the sunk cost fallacy with the case of a huge snowfall that pours onto the city the very same day we were planning to attend a theatre play whose tickets we had bought the previous days and are not refundable. Elster points out that, since our attendance to the play will not bring the money we had paid for the tickets back, there is no reason to make the decision on whether or not to attend the play on the basis of the sunk costs of the tickets. The correct reasoning should take into account only the cost of enduring the heavy snowfall in order to reach to the theatre where the play would be performed. Nevertheless, the same Jon Elster makes the disclaimer that a zealous observance of avoiding the sunk cost fallacy could lead to make choices following non transitive preferences.

If we change our mind every day, discarding previous decisions and assuming a new direction just because a new opportunity has arisen, we risk to end up in the ruin. Transitive preferences tend to assure the agent of a certain profit and non transitive ones exposes him to losses. In evolutionary games simulations, agents who act according to transitive preferences outshine agents who do not. It seems, then, that the rational agents walks on the edge of the razor, between sunk cost fallacies and non transitive preferences.

That is why there is not such a thing as a sunk cost fallacy. The rational agent, to be such, must ponder a whole plan against an alternative plan in a whole as well, which in some cases, both of them last several periods of time. It is true that in the “very short term” all past costs are sunk and that it only matters the opportunity costs, but most decisions are made in the short term, which lasts more than just a moment. Otherwise, the very concept of transitive preferences would lack any meaning.

Of course certain costs are sunk: if the flux of earnings that a good of capital produces just covers the variable costs of putting it to work (for example, a truck whose earnings just pay for the gas and the salary of the driver), the more rational choice is to use it until it becomes full obsolete and do not replace it with a brand new unit.

But the sunk cost fallacy does not provide a criterion to distinguish sunk costs from just mere costs of a single plan. What a rational agent with transitive preferences discards in his considerations will be named sunk costs, and what he does not, will not. A pure tautology.

Even the snowfall case does not explain satisfactorily the said fallacy: when the agent bought the tickets, their cost were inferior to the income of watching the play, but a heavy snowfall adds not a marginal cost but increases the marginal cost of the plan composed by the cost of the tickets plus the cost of enduring the snowfall.

Notwithstanding, the sunk cost fallacy derives into a philosophical puzzle: what is the subject? How are relations between time and being and between being and becoming. It seems that our permanence as rational agents depends mostly upon not to put into practice the opportunistic approach of the sunk cost fallacy ad libidum.

Moreover, the matter has a political strand: constitutional constraints demand from the authorities to take into account the weight of certain principles in their decisions and those principles could be disregarded if the decisions are purely made on the basis of expediency. If it is the same authority the one who decides whether certain constitutional principle should be followed or not, then all the citizens would be left exposed to arbitrariness.

The considerations about the length of the period a plan should last, the responsibility upon the consequences of our past choices, and the weight of the constitutional principles on the legitimacy of political decisions, become rational if they are not pondered by an isolated agent but in the framework of the interplay among several agents.

This framework of human interaction upon which the agent’s choices take place had been characterised by Friedrich A.Hayek as a spontaneous, or abstract or extended order. He proposed to leave the term “economics” to the explanation of the choices made by an isolated agent and to establish the science of “catallaxy” as the study of the complex phenomena involved in the said structure of interactions. In the same line, James M.Buchanan labelled the interplay of individual agents as “symbiosis” and proposed to redefine the task of the political economy to its study.  More recently, in 2009, Douglass C. North, John Joseph Wallis and Barry R. Weingast, in Violence and Social Orders: A Conceptual Framework for Interpreting Recorded Human History, coined the term “open access orders” to analyse the same set of events. To this stream of thought, it also belongs Vernon L. Smith’s own account of the concept of ecological rationality.

Catallaxy, Symbiosis, Complex Phenomena, and Open Access Order or Ecological Rationality are some of the aspects of what Karl Popper once called “critical rationalism” and supersedes old problems such as those of the instrumental or subjective reason. An authentic “toolbox,” ready to be used.