Novel Challenges to the Interaction between “Deliberation” and “Voting” in Modern Democratic Processes: A Paradox Presented by the Axiom of Non-Negative Response toward Democratic Deliberation.


Introducing a groundbreaking discovery that illuminates the intricate interplay between ‘discussion’ (deliberation) and ‘voting’—the foundational pillars of contemporary democracy. This pioneering research delves into a two-step democratic process, wherein participants engage in ‘discussion’ (deliberation) with fellow participants before proceeding to the crucial act of ‘voting’. It uncovers the essential normative relationship that should govern the connection between ‘discussion’ (deliberation) and ‘voting’.
Presenting a groundbreaking normative principle, denoted as ‘NNRD’, which advocates that individuals who have effectively persuaded others during the deliberative phase should not face adverse outcomes in the subsequent voting stage as a result of their persuasive success.
Offering a theoretical proof that establishes the inherent impossibility of devising a ‘voting’ mechanism capable of simultaneously honoring unanimous individual preferences, ensuring equitable treatment for all, and upholding the newly proposed ‘NNRD’ principle. This seminal contribution provides valuable insights into the development of novel democratic procedures that effectively integrate both ‘discussion’ (deliberation) and ‘voting’ components.

What we know from previous studies (e.g., scientific and historical background)

“Social choice theory” represents a prominent branch of political economy devoted to examining the derivation of social outcomes from individual preferences. Notably, it delves into the performance and implications of various voting rules, such as majority voting, plurality rule, Borda rule, and others. Within social choice theory, a notable body of work revolves around “impossibility theorems” that reveal the absence of voting rules or decision procedures capable of simultaneously satisfying essential normative principles. These principles demand that voting rules yield rational, non-arbitrary, stable, and fair social outcomes.

As a consequence of these findings, scholars have recognized that the mere adoption of a specific aggregative voting rule is not sufficient for the establishment of a genuine justification of a given decision. This realization stems from the inherent limitations of aggregative voting outcomes, which fail to guarantee the attainment of rational, non-arbitrary, stable, and fair results. Consequently, scholars and democratic theorists have embraced a paradigm shift, known as the “deliberative turn,” wherein democratic legitimacy and justification are grounded in the process of democratic deliberation, rather than relying solely on voting.

This transformative concept posits that outcomes possess democratic legitimacy when they can be reached through a free and reasoned agreement among equals. Joshua Cohen captures this essence aptly, stating, “Outcomes are democratically legitimate if and only if they could be the object of a free and reasoned agreement among equals” (“Deliberation and Democratic Legitimacy”).

Novel objectives and aims of the research

There is now a growing consensus among democratic theorists that ‘deliberation’ and ‘aggregation’ (or voting) have their own respective virtues and that each plays an important role in the democratic process that cannot be properly reduced to the role performed by the other. The political philosopher and democratic theorist Robert Goodin neatly summarizes this in the following slogan: `First talk, then vote.’ (Goodin 2008, Innovating Democracy: Democratic Theory and Practice after the Deliberative Turn: 124). Therefore, we assume the implementation of a two-stage democratic process, wherein the participants engage in reasoned democratic deliberation in the first stage and then vote for a particular outcome in the second aggregative voting stage. Our paper investigates what the proper normative relationship between the first stage of democratic deliberation and the second stage of voting should be.

Newly developed methods and inferences drawn using them

To achieve this objective, we put forth a novel axiom termed “NNRD” (Non-Negative Response toward Democratic Deliberation). The fundamental principle underlying NNRD asserts that, in the event individuals alter their preferences in response to persuasive democratic deliberation, the social choice rule should ensure that these persuaders do not face detrimental consequences as a result of their successful persuasion (refer to Figure 1). Put simply, any voting rule that places those who have effectively persuaded others at a disadvantageous position due to their successful deliberative efforts should be avoided.

Through meticulous and logically rigorous analysis rooted in social choice theory, we demonstrate that no aggregative voting rule can simultaneously fulfill the requirements of NNRD alongside other mild axioms that embody the core tenets of deliberative democracy, such as honoring unanimous consensus and political equality. Nonetheless, we propose two potential avenues of escape, although each necessitates the relinquishment of certain fundamental democratic values. For instance, one approach entails adopting a voting rule that defaults to a predetermined outcome unless there emerges a singular alternative that garners unanimous agreement. Alternatively, granting veto power to select individuals represents another potential solution. Nevertheless, both of these escape routes entail compromising either democratic efficiency through unanimous consensus or political equality.

Figure 1 depicts a scenario where, in the absence of deliberation (‘talk’), a park is selected through a vote. However, after successful persuasion by park supporters during deliberation, the outcome shifts, and a road is ultimately chosen instead. This example exemplifies the need for our newly proposed principle, ‘NNRD’, which aims to prevent situations wherein individuals who have effectively persuaded others find themselves in a worse-off position as a consequence of their persuasive efforts, solely due to the voting outcome.
Ripple effects and social impact of research

Our research findings indicate the formidable challenges associated with devising a two-stage democratic process that effectively integrates democratic deliberation in the initial stage and aggregative voting in the subsequent stage, while simultaneously ensuring that the voting outcomes faithfully reflect the outcomes of successful deliberation and uphold unanimous preferences and political equality. Consequently, these findings raise significant concerns regarding the overall credibility of our democratic processes, even when they incorporate elements of democratic deliberation.

Future challenges

In light of our impossibility theorem, it becomes imperative to explore additional avenues, commonly referred to as “escape routes,” that enable us to reconcile the principles of NNRD with the preservation of other fundamental normative values inherent in deliberative democracy. These escape routes serve as crucial means to navigate the challenges posed by the theorem and seek viable solutions that honor NNRD while upholding the essential tenets of deliberative democracy.

Researcher’s comments

We all hope that our democratic system engenders favorable political outcomes that enhance and advance society as a whole. However, the presence of numerous impossibility theorems within social choice theory has unveiled the inherent instabilities and arbitrary nature of relying solely on aggregative voting procedures. Consequently, one of the primary motivations for incorporating deliberation into our democratic process is to address these deficiencies associated with aggregative voting. However, even if democratic deliberation is performed successfully, it would be futile if the successful outcomes of such deliberation fail to translate effectively into improved political outcomes during the subsequent aggregative voting stage. It is our intention that our research serves as a catalyst, fostering greater awareness among politicians and policymakers regarding the limitations intrinsic to our democratic processes. By doing so, we aim to inspire endeavors aimed at refining and enhancing our overall democratic decision-making process, ultimately benefiting society at large.

*1 Impossibility Theorem

Within the realm of social choice theory, an impossibility theorem attests to the absence of a voting or decision procedure capable of fully satisfying a specific set of ideal conditions, commonly referred to as axioms. These axioms represent fundamental principles that voting and decision procedures are expected to adhere to. Among the most renowned impossibility theorems is Arrow’s impossibility theorem, formulated by the distinguished scholar Kenneth Arrow. This theorem establishes that, under specific rational conditions, it is impossible to achieve a fair derivation of social preference from individual preferences.

*2 Democratic deliberation

Democratic deliberation is the practice of engaging in transparent and public discussions and debates centered around a specific agenda. It serves as a vital platform, enabling individual citizens to freely express their perspectives while actively listening to and considering the viewpoints put forth by fellow citizens. Through this process, participants have the opportunity to engage in mutual persuasion, fostering an environment where reasoned arguments are exchanged. The intended outcome is twofold: firstly, to broaden participants’ understanding by exposing them to new perspectives, and secondly, to encourage the critical evaluation and potential revision of their own viewpoints. Ultimately, democratic deliberation seeks to leverage this collective exchange of ideas to drive the democratic process towards the achievement of improved social outcomes.


Journal: American Journal of Political Science
Title of original paper: (The Impossibility of) Deliberation-Consistent Social Choice
Authors:Tsuyoshi ADACHI (Waseda University, FPSE) Hun CHUNG (Waseda University, FPSE); Takashi KURIHARA (Tokai University, FPSE)
Article Publication Date: 8 May 2023