The Indian media has scrambled to play the vigilante, led by Indian Express’s first page news headline. The urge to fight the partisan battle is encouraging a race to the bottom of intellectual rigour. As a relatively serious researcher I balked at the evidence presented by Shoaib Daniyal (Scroll, August 1st 2015) against death penalty acting as a deterrence to crime. Using case studies from United States the author concluded that “there is a consensus on the redundancy of the death penalty in deterring crime.” Even ignoring the adage of one size does not fit all i.e. there may be structural differences in the experience of United States and India, I have to point out serious methodological deficiencies in the author’s claim.
1. Correlation is not causation
The author contends that the correlation between homicide rates and death penalty should be the holy grail for its deterrence effect. Correlation, however, does not imply causation and at best acts as an eyeball test. Correlation between two variables are quite often spurious and driven by other explanatory variable (s). We really need empirical evidence on causal effect of death penalty on homicide rates to arrive at any conclusion.
2. Literature evolves
The author uses one empirical study published in 1950s as evidence against any correlation between rates of homicide and death penalty. While I don’t expect the writer to have presented a thorough literature review, a look at recent empirical evidence would have been instructive. For example Dezhbakhsh and Shephard (2006) in a panel study of 50 states show almost 23 percent increase in murder rates during the period when United States Supreme Court imposed a moratorium on death penalty (1972-76), compared to the years before and after. The authors also find a significant variation across states in murder rates’ response to death penalty.
3. Brutalization effect does not capture state characteristics
The writer refers to Brutalization effect i.e. increase in murder rates with the death penalty as a “compelling” evidence against death penalty. He however does not account for two key issues- the problem of reverse causality i.e. states may impose death penalty in response to high homicide rates, which may explain why states without death penalty have lower murder rates than states with a death penalty. Second, there may be other institutional factors explaining the fall in death rates in North Carolina or California, after the removal of death penalty. For example Levitt (2001) in his seminal paper showed that legalized abortion in 1970s accounted to about 50 percent drop in crime in the 90s. In other words the association between death penalty and lowering of murder rates may be due to a third explanator.
The existing empirical evidence, as admitted by the writer, points towards some deterrence effect of death penalty in the United States. Majority of the empirical literature in the past decade show that death penalty has a deterrent effect. For example, out of 22 empirical studies on death penalty 14 report some deterrence, seven show no effect while one is inconclusive. One could debate on the efficacy of death penalty while factoring in moral considerations. For example, if an additional death sentence causes two fewer homicides we can debate on its utility to the society. However, to put together shoddy argumentation as critical scrutiny is a blatant disregard of the reader’s intellectual capacity.
 Dezhbakhsh, Hashem, and Joanna Shepherd, "The Deterrent Effect of Capital Punishment: Evidence from a Judicial Experiment," Economic Inquiry 14 (2006): 512-535.
 John J. Donohue & Steven D. Levitt, 2001. "The Impact Of Legalized Abortion On Crime," The Quarterly Journal of Economics, MIT Press, vol. 116(2), pages 379-420, May.
 Hashem Dezhbakhsh & Paul Rubin, 2007. "From the "Econometrics of Capital Punishment" to the "Capital Punishment" of Econometrics: On the Use and Abuse of Sensitivity Analysis," Emory Economics 0715, Department of Economics, Emory University (Atlanta).