Writing in a review of Justin Fox’s book The Myth of the Efficient Market, Richard Thaler (2009) has drawn attention to two dimensions of the efficient markets hypothesis, what he refers to as:
- ‘No free lunch’, what economists refer to as ‘informational efficiency’;
- ‘The price is right’, what economists refer to as ‘Pareto efficiency’.
My recent research with Carine Nourry and Alain Venditti argues that while there are strong reasons for believing there are no free lunches left uneaten by bonus-hungry market participants, there are really no reasons for believing that this will lead to Pareto efficiency, except, perhaps, by chance (Farmer, Nourry, Venditti 2012).
In separate work, I look at the policy implications of this, showing that the Pareto inefficiency of financial markets provides strong grounds to support central bank intervention to dampen excessive fluctuations in the financial markets (Farmer 2012b). These are strong and polarising claims. They are not made lightly.
Not irrationality, frictions, sticky prices nor credit constraints
Some economists will be sympathetic to my arguments because they believe that financial markets experience substantial frictions. For example, it is frequently argued that agents are irrational, households are borrowing constrained or prices are sticky. Although there may be some truth to all of these claims, my argument for direct central bank intervention in the financial markets does not rest on any of these alleged market imperfections.
Other readers of this piece will wish to challenge my view based on the assertion that competitive financial markets must necessarily lead to outcomes that cannot be improved upon by government intervention of any kind. That assertion has been formalised in the first welfare theorem of economics that is taught to every first-year economics graduate student.
The first welfare theorem provides conditions under which free trade in competitive markets leads to a Pareto efficient outcome, a situation where there is no way of reallocating resources that makes one person better off without making someone else worse off. In my work with Nourry and Venditti (Farmer, Nourry, Venditti 2012), we show why the conditions that are necessary for the theorem to hold do not characterise the real world.
We make some strong but standard assumptions:
- Households are rational and plan for the infinite future;
- They have rational expectations of all future prices;
- There are complete financial markets in the sense that all living agents are free to make trades contingent on any future observable event