The debate about Piketty’s book remains unabated (see Steve Horwitz’s and Bas van der Vossen’s posts and references therein.) I cannot contribute to this debate because (with the exception of its normative premises) I am unqualified to do so. Rather, I’d like to address the problem of confirmation bias. As is known, the book was enthusiastically and rather uncritically received by progressives. This enthusiasm sounds like a case of confirmation bias. Progressives are in dire need of a sound argument for coercively redistributing wealth, and here they have one. Similarly, some libertarians and conservatives might have been too quick in rejecting the book, for symmetrical reasons.

My own attitude is to practice what I preach and try to avoid confirmation bias. Non-economists (philosophers, political scientists, jurists) often need to assess empirical theories and facts. For example, suppose a philosopher wants to argue that justice requires helping the poor and is trying to decide whether the minimum wage does that. Let us assume that 50% of reliable research says no, the minimum wage causes unemployment and thus does not help the poor, while 50% of equally reliable research says yes, the minimum wage does not have that effect and therefore helps the poor. Since the issue is unresolved, the professional obligation of the philosopher is, I contend, to suspend judgment. She is not entitled to argue for the minimum wage anyway. The assertion “economists do not agree about the minimum wage; therefore, I am entitled to support it” is fallacious, because the one reason to support the minimum wage, that it is supposed to help the poor, is unavailable.

But by the same token, it is wrong to exaggerate the lack of consensus. For example, specialists converge on the beneficial effects of trade. Say 95% of economists affirm this. The philosopher (or historian, whatever) is not entitled to pick the 5% outliers and say that the issue is unresolved or, worse yet, to oppose trade because he is convinced by the outliers. He is not a specialist, so by definition he is not in a position to arbitrate on the issue even if the split was greater than it is.

The same rationale applies to the assessment of Piketty by non-specialists. Specialists are debating right now two crucial empirical issues in the book: the highly technical question of the rate of return of capital and the less technical but still specialized empirical data about the increase of inequality over time. To me, those issues are, for now, unresolved and I therefore suspend judgment.