Market failure is bad for your health but social injustice is worse.

Smith and Petticrew succinctly outline the challenges we face in evaluating the impact of public health interventions tackling social determinants: challenges driven by multiple agencies with varying and sometimes conflicting interests, complex causal pathways and outcomes that extend beyond health. Looking ahead they call for a new evaluation approach, one that focuses on the whole before it focuses on any single part: a macrorather than a micro-approach. They generously invite comment, which is valuable as their conclusions are important and bear repetition and re-emphasis. Some readers may take issue with points they make along the way. Does the contemporary agenda on socio-economic factors really represent a move away from infectious disease when prevalence of diseases such as tuberculosis remains one of the most blatant indicators of a breakdown in social and economic structure? Is the interest in social determinants really so recent or have the authors overlooked the efforts of Farr, or Virchow and others who followed who saw poverty and its associated social and political conditions as the root cause of ill health and political reform, economic development and education as legitimate instruments of public health? Others will not see themselves in the simple portrait painted of the micro-evaluation even when they locate themselves in that camp. The use of mixed methods, while not common, is not the exclusive domain of macro-evaluation. Complex logic models and techniques such as structural equation and multi-level modelling belie the claim that only single cause-effect models are employed. Measurement of non-health outcomes such as community capacity, empowerment, educational achievement and employment features in many evaluations of public health. Perspectives extend way beyond patients and health professionals. Indeed the field of community-based participatory research has developed sophisticated protocols and codes of ethics for involving community partners in research. We could discuss any of these issues, but I would like to take us back to a point made in the introduction, specifically that public health intervention is best limited to instances of market failure, to challenge and examine the consequences of this framing. Market failure is the term that economists use to describe situations where one person incurs costs or enjoys the benefits of another’s action. Second hand smoke and the spread of infectious disease from the unvaccinated are prime examples. Government intervention may then be warranted to correct the imbalance. Market failure limits when government can act and what it can do when it does act. For example, the great public health reformer, Edwin Chadwick used market failure to argue for publicly funded improvements in sanitation and to limit any obligation government had to address other social ills such as poverty and homelessness. But economic considerations such as market failure are just one rationale for government intervention. Social justice is another. Chadwick acted not out of any sense of social justice but in defence of class interest: as evidenced by his administration of England’s poor laws. Concerned that relieving the poor of the health consequences of their unsanitary habits might encourage slovenly behaviour, Chadwick’s