Skepticism is prudent in all scholarly disciplines, including the social sciences, because error is always possible in scholarly work. Social scientists, therefore, may not reach the correct conclusion about whether the frequency of a societal activity is affected by an intervention such as law or government policy. Unsurprisingly, studies in the social sciences, as well as studies in the natural sciences, have reported findings as to cause-effect relationships that were not reproduced in follow-up research.

Since the booby traps in quantitative research on law/policy effectiveness are not widely known, a pool of unwary consumers exists for the findings of flawed research. Notably, this pool includes persons concerned with the numerical size of the human population who believe that social science research has proven that the adoption and implementation of policies expanding the availability of family-planning methods bring about a relatively rapid and large diminution in human fertility and population growth. According to this belief, policies that promote access to family planning on their own materially lower the incidence of childbearing. For example, in a publication by a leading university-based school of public health in the United States, five former directors of the population and reproductive health program at the U.S. Agency for International Development contended that the provision of family-planning services in the past has cut the global rate of growth of the human population, that the magnitude of global population growth in years to come will ‘depend[] largely upon future rates of contraceptive use,’ and that the worldwide use of contraception will expand in the future only if the United States appreciably increases the assistance it provides internationally for family planning. Their contention, moreover, was tied to empirical research: Studies of the impact of programs involving the ‘community-based distribution’ of family-planning methods and information, the authors wrote, have yielded ‘impressive results in dozens of countries throughout the developing world’ and have demonstrated a significant role for these programs in leading couples to rely on contraceptives.

Are claims like these accurate? Can the numerical increase of Homo sapiens be materially reduced just by creating and expanding family-planning programs? The answer should begin with a brief overview of types of deficiencies that can lurk in research on law/policy effectiveness.