It is common to argue that the U.S. public has a political polarization problem. This perceived division within the American populace understandably generates concern among the nation’s allies, such as Japan, who rely on a stable and dependable United States to maintain robust bilateral relations. A “Disunited States” could potentially undermine the trust and cooperation that underpin international alliances, particularly in areas like security and trade, which are vital to the Japan-U.S. partnership. Before accepting this premise at face value, however, it is important to scrutinize the evidence supporting the claim of polarization. What exactly constitutes polarization, and how do we ascertain its presence and extent within the U.S.? These questions are foundational to understanding the issue and its implications.
The United States has operated under a two-party system for nearly its entire history, a structure that inherently fosters political competition. Every two or four years, during congressional and presidential elections, significant segments of the population cast votes for opposing candidates and align themselves with different political parties. Historically, this pattern of alternating support has not been interpreted as a symptom of dysfunction. On the contrary, political disagreement—even when it spans a wide array of issues and policies—is widely regarded as a natural and healthy feature of a functioning democracy. The ability of citizens to express divergent views and engage in robust debate is a cornerstone of democratic governance, ensuring that no single perspective dominates unchecked.
To delve deeper into the nature of polarization, it is useful to consider the distinctions drawn by Robert Tallisse and Scott Aikin, philosophy professors at Vanderbilt University.[1] They differentiate between “political polarization” and “belief polarization,” arguing that the latter poses a far greater threat to societal cohesion. Political polarization refers to the divergence of policy preferences or ideological leanings among individuals or groups, a phenomenon that can coexist with civil discourse and compromise. Belief polarization, however, is a more insidious process, wherein “interactions with like-minded others transform us into more extreme versions of ourselves.” This escalation of conviction, driven by echo chambers and reinforced by group dynamics, can erode the capacity for dialogue and mutual understanding, pushing individuals toward intransigence.
Given these definitions, how do we assess the level and type of polarization present in the U.S. today? This inquiry is not merely academic; it carries significant implications for international relations, particularly between the U.S. and Japan. For Japan, understanding the American public’s attitudes toward their nation—both as a country and in terms of specific policies like joint security arrangements or trade agreements—is critical to gauging the reliability of their partnership. Are Americans polarized in their perceptions of Japan? Do they view the alliance with enthusiasm, skepticism, or indifference? These questions remain underexplored, yet they are essential to evaluating the health of the bilateral relationship.
Public opinion polls offer one avenue for addressing these uncertainties. In both the U.S. and Japan, polling is a common tool for gauging societal attitudes. Media outlets often fixate on “horse-race polls,” which track candidates’ electoral prospects or, in Japan’s case, a cabinet’s approval ratings based on sampled public opinion. While these snapshots generate headlines, they reveal little about the electorate’s stance on substantive policy matters. In democratic systems, polls that probe public support for specific policies arguably hold greater value than those focused solely on electoral horse races. Policy-oriented polling can illuminate the priorities and divisions within a population, providing a clearer picture of where consensus or contention lies.
Regrettably, polling questions focused on foreign policy are scarce in both nations’ surveys, and those specifically addressing the Japan-U.S. relationship are rarer still. This paucity of data might suggest a lack of controversy surrounding the alliance, as pollsters tend to gravitate toward areas of conflict or public unease. The relative stability of U.S.-Japan relations—marked by decades of cooperation in security, economic, and cultural spheres—may explain this gap. However, the absence of polling does not necessarily confirm consensus; it could simply reflect a lack of attention to the issue. Even if more foreign policy polling data were available, particularly concerning Japan-U.S. policies, its accuracy would remain a matter of debate, especially in the U.S., where polling faces significant methodological challenges.
One of the most pressing issues in U.S. polling is non-response bias, a problem that undermines the reliability of survey data. Non-response bias occurs when a substantial portion of the population declines to participate in polls, leaving researchers with a sample that may not represent the broader public. In practice, very few Americans respond to polls today, rendering those who do a self-selecting minority—potentially outliers in their views or behaviors. While polling techniques have grown more sophisticated, with statistical weightings applied to correct for sampling imbalances, the sheer scale of non-response has become increasingly difficult to mitigate. According to researchers Amnon Cavari and Guy Freedman, survey response rates in the U.S. have plummeted from around 70 percent in the 1980s to less than 10 percent in recent years, a decline that complicates efforts to measure public opinion accurately.[2]
Cavari and Freedman identify two primary drivers of this drop in response rates. The first is the challenge of contact rate. In an era where nearly everyone has caller ID on their phones, people routinely screen out calls from unfamiliar numbers, including those from pollsters. If individuals cannot be reached, they cannot be polled, and there is no clear evidence that the decision to ignore unknown callers correlates with specific political or policy preferences. This factor, while significant, is relatively neutral in its impact on polarization measurements. The second driver, however, is more troubling. Among those who do answer a pollster’s call, many refuse to participate once they learn the purpose of the outreach. Cavari and Freedman’s research reveals that those who ultimately cooperate tend to be highly politically engaged—a group that is not necessarily representative of the general population.
This self-selection among respondents has profound implications for assessing polarization, particularly belief polarization. In the context of historically low response rates, the characteristics of those who opt into policy surveys become critical. Highly engaged individuals, by virtue of their immersion in political discourse, are more susceptible to belief polarization, at least on domestic issues. They are more likely to inhabit ideological echo chambers, consume partisan media, and align closely with their chosen political tribes. As a result, survey data may disproportionately reflect the views of these polarized outliers, skewing perceptions of division within the broader public. If politicians rely on such data to guide their decisions, they may adopt more extreme positions, further amplifying the cycle of polarization.
Intriguingly, Cavari and Freedman propose a distinction between the effects of non-response bias on domestic versus foreign policy data. They argue that politically engaged respondents, while prone to polarization on domestic matters, may be less so on foreign policy questions. These individuals are often better informed about international affairs, potentially leading to more nuanced and less dogmatic views than those of the general public. If true, this suggests that U.S. voters might be more polarized on foreign policy than surveys indicate—a counterintuitive finding that challenges conventional assumptions.
This hypothesis, however, is not without its flaws. Recent political developments, such as the stark partisan divide over U.S. support for Ukraine and European security, suggest that polarization extends beyond domestic issues into the foreign policy realm. The Republican and Democratic parties have rarely been more at odds on such matters, making it harder to accept that highly engaged partisans shed their ideological leanings when addressing international concerns. For instance, debates over military aid to Ukraine or responses to China’s rising influence reveal deep fissures that mirror domestic divides, complicating the notion of a more moderate foreign policy consensus among the engaged.
Turning to the U.S.-Japan relationship, these dynamics underscore the need to account for non-response bias when evaluating polarization’s impact. Without reliable data, assumptions about American attitudes toward Japan—whether supportive, ambivalent, or hostile—remain speculative. This uncertainty highlights several avenues for future research:
- How do survey response rates in Japan compare to those in the U.S., and what factors account for any differences?
- Are variations in response rates driven by cultural attitudes toward surveys, technological differences, or distinct polling methodologies?
- What do existing survey data reveal about polarization on foreign policy issues within the Japanese public?
- How do U.S. and Japanese attitudes align or diverge on specific foreign policy challenges, such as Ukraine, Gaza, China, Taiwan, and North Korea?
Addressing these questions could illuminate the true extent of polarization and its implications for the U.S.-Japan alliance, offering a clearer path forward for both nations in an increasingly complex global landscape.