Chapter 1 described the puzzling turnaround in attention to national security by conservative Japanese politicians in 1997. Chapter 2 argued that this is best explained by a shift in their electoral strategies from pork for groups of voters in their respective districts to broad policy issues like national security, brought about by electoral reform to the House of Representatives (HOR) in 1994. Chapter 3 explained how candidate election manifestos and quantitative text analysis were used to obtain measures of the degree to which each of the 7,497 serious candidates competing in the eight HOR elections between 1986 and 2009 were relying on pork, policy, and within the policy category, national security policy. Chapters 4, 5, and 6 used those measures to test four hypotheses derived from the argument. Chapters 5 and 6 derived eight categories of alternative hypotheses that could plausibly account for both the shift in strategies and the turnaround in attention to national security, and tested those using measures of the ideological positions adopted by candidates during these eight elections, the topics of 126,275 voter petitions presented to the Diet during this time, public opinion polls, and other new data. Together, these chapters provide compelling evidence that conservative Japanese politicians began paying more attention to national security in 1997 because their electoral strategies changed, and not because of any other variable.
This begs the question, what influence has their new attention to national security had on Japanese security policy? Before answering this question, it is important to think about why it is difficult to evaluate the relationship between their new electoral strategies and Japanese security policy. This is because we cannot observe what Japanese security policy would have looked like in the absence of their new electoral strategies. The standard approach for scholars interested in evaluating the causal impact of a treatment like electoral reform on an outcome like security policy is to identify a set of countries that resemble Japan, some of which received the treatment and some of which did not, and examine what their security policies look like after some received the treatment. If the security policies across the two sets of countries were then found to vary, we could attribute that variation to the effects of the treatment because we know the countries were similar in other regards before they received the treatment.