Alternative Digital Platforms and the Renewal of the Public Sphere: Decidim and the Democratic Governance of Participatory Infrastructures

Abstract

The objective of this article is to examine how alternative digital platforms can be designed and governed as public-interest infrastructures capable of supporting democratic deliberation in the contemporary digital public sphere. Drawing on deliberative democratic theory, the article develops a normative framework for evaluating participatory digital infrastructures and applies it to a qualitative, theory-driven case study of Decidim, an open-source participatory platform originally developed by the Barcelona City Council. Methodologically, the study combines normative analysis with qualitative documentary analysis of official platform documentation, peer-reviewed academic literature, and the institutional and technical features of the platform. The analysis shows that Decidim operationalises key deliberative principles—such as inclusion, publicity, reason-giving, transparency, traceability, and participatory governance—through its institutional design, governance model, and deliberative affordances. The findings demonstrate that algorithmic systems and digital infrastructures are not inherently incompatible with democratic values, but can be intentionally engineered to support public deliberation and democratic will-formation. The article concludes that the reconstruction of participatory digital infrastructures as public goods constitutes a democratic imperative, requiring sustained institutional commitment, political will, and a reconceptualisation of platform design as a domain of democratic governance.

1. Introduction

The rise of social media platforms was initially accompanied by emancipatory narratives promising horizontal communication, the removal of traditional gatekeepers, rapid political mobilisation, and the democratisation of public expression. Early techno-optimist accounts portrayed these platforms as tools capable of revitalising public spheres weakened by media concentration and institutional distance between citizens and decision-makers. In this vision, digital networks appeared as infrastructures of participation, enabling citizens to voice concerns, coordinate collective action, and engage more directly with political institutions.

Over the past decade, however, this emancipatory promise has been increasingly called into question. A substantial body of research in political communication, media studies, sociology, and democratic theory has documented how dominant social media platforms contribute to fragmentation, polarisation, and epistemic instability within the public sphere (Habermas 2022; Helberger 2020; Zuboff 2019; Gillespie 2018). Algorithmic personalisation systems prioritise engagement-driven metrics, amplify emotionally charged and polarising content, and segment publics into relatively isolated communicative enclaves (Helberger 2020). At the same time, opaque governance structures and surveillance-based business models concentrate communicative power in private hands, undermining transparency, accountability, and public control over the infrastructures that increasingly mediate political life (Zuboff 2019; Pasquale 2015).

These dynamics are often described through the concept of algorithmic rationality. Whereas deliberative democracy presupposes communicative rationality—characterised by argumentation, reciprocity, openness to revision, and the possibility of mutual understanding—algorithmic rationality prioritises predictability, attention capture, and behavioural optimisation (Habermas 1996; Pasquale 2015; Srnicek 2017). The problem, therefore, is not political disagreement as such, which is constitutive of democratic pluralism, but rather the emergence of socio-technical environments that structurally weaken shared horizons of meaning, reduce the visibility of reasoned argument, and accelerate cycles of outrage and performative communication (Habermas 2022; Helberger 2020).

Parallel to the critique of commercial social media platforms, recent research in digital government and public administration has mapped and evaluated a growing ecosystem of digital tools designed to support citizen participation, transparency, and collaborative governance (Fung 2015; Nabatchi and Leighninger 2015; Shin 2024). This literature analyses how participatory platforms and civic technologies are increasingly deployed by public institutions to structure consultation, deliberation, and co-production, while also raising questions about democratic quality, institutional responsiveness, and public value creation (Shin 2024; Cardullo 2025). Rather than treating digital participation as an extension of social media logics, these studies conceptualise participatory platforms as distinct institutional and technological arrangements embedded within public governance frameworks (Fung 2015; Nabatchi and Leighninger 2015).

Against this background, the present article argues that democratic renewal in the digital age requires a shift from the critique of existing platforms to the intentional design and governance of alternative digital infrastructures oriented toward public interest and democratic values. Specifically, it advances the claim that participatory platforms should be conceived not as neutral technical tools or private innovations, but as public goods whose design, governance, and algorithms are subject to democratic justification and collective control (Habermas 1996; Helberger 2020; Zuboff 2019).

To develop this argument, the article draws on deliberative democratic theory as a normative framework for evaluating the democratic quality of digital participation infrastructures. Deliberative theory emphasises inclusion, publicity, reciprocity, reason-giving, and accountability as conditions of legitimate collective decision-making (Cohen 1989; Habermas 1996; Bohman 1996; Dryzek 2000). From this perspective, the democratic potential of digital platforms depends not only on the volume of participation they enable, but on how they structure interaction, visibility, agenda-setting, and the connection between public reasoning and institutional decision-making (Mansbridge et al. 2012; Habermas 2022).

Empirically, the article examines Decidim, an open-source participatory platform originally developed by the Barcelona City Council and subsequently adopted by public institutions and civic organisations in multiple countries (Barcelona City Council 2023; Decidim n.d.-a, n.d.-b). Decidim is analysed as a paradigmatic case of a participatory infrastructure explicitly designed as a public-interest platform, combining open-source development, institutional embedding, and participatory governance of rules and technical evolution (Barandiaran et al. 2019; Barandiaran et al. 2024). Rather than treating Decidim as a purely technical solution, the analysis situates it as a socio-technical and institutional arrangement that operationalises normative commitments to democratic deliberation (Barandiaran et al. 2024; Mansbridge et al. 2012).

The article is guided by the following research questions:

• RQ1: How can digital participatory platforms be designed and governed as public-interest infrastructures rather than commercial communication systems?
• RQ2: Which normative principles derived from deliberative democratic theory are relevant for evaluating the democratic quality of participatory digital platforms?
• RQ3: To what extent does Decidim operationalise these deliberative principles through its institutional design, governance model, and participatory affordances?

These questions are addressed through a theory-driven qualitative case study of Decidim, combining normative analysis with the examination of institutional arrangements and platform functionalities (Fung and Wright 2003; Barandiaran et al. 2019; Borge et al. 2022). By articulating deliberative democratic theory with the analysis of an existing participatory platform, the article seeks to demonstrate that algorithmic systems and digital infrastructures can be governed in ways that support democratic will-formation rather than undermine it (Habermas 1996; Dryzek 2000; Helberger 2020).

2. Deliberative Democracy as a Normative Perspective

Deliberative democracy provides a demanding normative framework for assessing the democratic quality of contemporary communication infrastructures. Its core claim is that legitimate collective decisions should arise not merely from the aggregation of preferences, strategic bargaining, or electoral competition, but from inclusive processes of public reasoning in which participants exchange arguments, justify claims, and remain open to revision (Cohen 1989; Habermas 1996; Bohman 1996; Dryzek 2000). Although deliberative theories differ in emphasis and scope, they converge on a set of core requirements, including inclusion of those affected by decisions, reciprocity among participants, publicity and accessibility of deliberation, and the provision of reasons that can be publicly scrutinised (Dryzek 2000; Mansbridge et al. 2012).

In its Habermasian formulation, deliberation is grounded in the concept of communicative rationality, understood as an orientation towards mutual understanding achieved through argumentation under conditions that minimise coercion and reduce asymmetries of power (Habermas 1987, 1996). Communicative rationality does not presuppose consensus or harmony, nor does it deny the presence of strategic action and structural inequalities. Rather, it offers a critical standard against which distortions of communication can be diagnosed and contested (Habermas 1987, 1996). From this perspective, the democratic legitimacy of political decisions depends on the extent to which they can be justified in processes of public reasoning that are inclusive, transparent, and responsive (Cohen 1989; Habermas 1996).

Within modern democracies, the public sphere occupies a central role in mediating between civil society and institutional decision-making. It functions as a space in which citizens articulate problems, exchange reasons, form opinions, and influence political agendas (Habermas 1996, 2022). Deliberative democracy therefore assigns particular importance to the conditions under which public communication takes place. When these conditions are systematically distorted—by unequal access, opaque selection mechanisms, or incentives that privilege emotional mobilisation over reasoned argument—the legitimacy-generating function of the public sphere is undermined (Habermas 2022; Helberger 2020).

This insight has become especially salient in the context of digital communication. While digital media initially appeared to expand opportunities for participation and expression, research has increasingly shown that dominant platform architectures introduce new forms of communicative distortion. Algorithmic ranking systems shape visibility and relevance according to engagement metrics that favour sensationalism, polarisation, and performative communication (Helberger 2020). At the same time, the opacity of platform governance and the concentration of infrastructural power in private actors weaken the possibility of public justification and democratic oversight (Gillespie 2018; Pasquale 2015).

From a deliberative perspective, these dynamics represent not merely empirical pathologies but normative failures. They indicate a growing disjunction between the requirements of communicative rationality and the operational logic of digital platforms (Habermas 2022; Helberger 2020). As a result, deliberative democratic theory offers both a critical lens for diagnosing the democratic deficits of contemporary digital infrastructures and a normative orientation for imagining alternative institutional and technical arrangements (Dryzek 2000; Mansbridge et al. 2012).

Crucially, deliberative democracy directs attention away from isolated acts of participation towards the systemic conditions that structure public reasoning. It emphasises that democratic legitimacy emerges from the interaction of multiple arenas, institutions, and communicative processes rather than from single platforms or events (Mansbridge et al. 2012). This systemic orientation is particularly relevant for the analysis of digital infrastructures, which increasingly function as connective tissue linking citizens, civil society organisations, and public institutions.

Against this background, deliberative democracy provides a coherent normative framework for evaluating digital participation platforms not in terms of user engagement or efficiency alone, but in terms of their capacity to support inclusion, reason-giving, accountability, and meaningful links between public discourse and institutional decision-making (Habermas 1996; Dryzek 2000; Fung 2015). It is this framework that underpins the normative architecture developed in the following section.

3. Principles for a Deliberative Normative Architecture

Building on deliberative democratic theory and critical scholarship on digital platforms, this article proposes five principles for a deliberative normative architecture for alternative participatory infrastructures. These principles do not describe a single ideal-type platform, nor do they prescribe specific technical solutions. Rather, they articulate normative and institutional commitments that can guide the democratic design, governance, and evaluation of participatory digital platforms conceived as public-interest infrastructures (Habermas 1996; Dryzek 2000; Helberger 2020; Winner 1980).

3.1. Public-Interest and Non-Commercial Governance

The first principle concerns the governance and political economy of digital participation infrastructures. A growing body of critical research argues that platforms organised around advertising, data extraction, and behavioural monetisation are structurally misaligned with democratic values (Zuboff 2019; Srnicek 2017). When communicative infrastructures are governed primarily as profit-generating assets, design choices tend to privilege engagement maximisation, attention capture, and predictive control over the quality of public reasoning (Pasquale 2015; Helberger 2020).

From a deliberative perspective, public-interest governance is therefore not merely an ownership issue, but a condition for communicative autonomy (Habermas 1996; Dryzek 2000). Platforms governed as public goods, commons-based infrastructures, or cooperative entities are more likely to align their design logics with democratic objectives such as inclusion, transparency, and accountability (Fung 2015; Mansbridge et al. 2012). Insulating participatory infrastructures from surveillance-based business models reduces incentives for manipulation and enables governance arrangements oriented towards public justification rather than market performance (Zuboff 2019; Pasquale 2015).

3.2. Algorithmic Transparency and Contestability

The second principle addresses the role of algorithmic systems in structuring participation, visibility, and relevance. In contemporary digital environments, algorithms function as powerful gatekeepers that shape which contributions are seen, amplified, or marginalised (Helberger 2020; Pasquale 2015). Yet these systems often operate through opaque logics that escape public scrutiny and democratic control (Pasquale 2015; Gillespie 2018).

Deliberative democracy requires that exercises of power be subject to public justification (Habermas 1996). Applied to algorithmic systems, this implies the need for transparency and contestability (Pasquale 2015; Helberger 2020). Transparency should not be understood merely as the disclosure of source code, which may be unintelligible to most users, but as the provision of meaningful explanations regarding how decisions are made and how criteria of relevance are applied (Aoki 2024). Contestability, in turn, refers to the institutional possibility for users and public authorities to question, audit, and revise algorithmic rules (Bignami 2022).

Embedding algorithmic systems within frameworks of democratic oversight and participatory governance enables deliberation not only within platforms, but about the platforms themselves (Mansbridge et al. 2012; Barandiaran et al. 2024). This meta-deliberative dimension is essential if digital infrastructures are to function as legitimate components of the democratic public sphere.

3.3. Civic Orientation and Public Value Creation

The third principle concerns the explicit orientation of participatory platforms towards civic purposes and public value. Unlike commercial platforms, whose success is measured through metrics such as user retention, engagement, and monetisation, deliberative platforms should be evaluated according to their contribution to democratic capacities, collective learning, and informed public debate (Fung 2015; Nabatchi and Leighninger 2015).

Public value theory provides a useful complement to deliberative democracy in this regard. It conceptualises institutional success in terms of social and democratic outcomes rather than efficiency or profitability alone (Fung 2015). Applied to digital participation infrastructures, public value entails fostering inclusive participation, protecting privacy, minimising data extraction, and strengthening trust between citizens and institutions (Shin 2024; Cardullo 2025).

By redefining success metrics and embedding civic objectives into design and governance choices, participatory platforms can resist the engagement-driven dynamics that dominate corporate social media environments (Helberger 2020; Zuboff 2019). This reorientation is crucial for creating digital spaces that support deliberation rather than amplify conflict and performative mobilisation.

3.4. Participatory Governance of Rules and Infrastructure

The fourth principle emphasises participatory governance of platform rules, policies, and technical evolution. Deliberative democracy stresses that legitimacy arises not only from outcomes, but from inclusive processes of rule-making and justification (Habermas 1996; Dryzek 2000; Mansbridge et al. 2012). Applied to digital platforms, this implies that users and affected stakeholders should have meaningful opportunities to participate in decisions regarding moderation policies, governance structures, and design changes (Gillespie 2018; Barandiaran et al. 2024).

Participatory governance transforms platforms from unilateral rule systems into arenas of collective self-government (Mansbridge et al. 2012). It distributes power over digital infrastructures more evenly and subjects design choices to public reasoning. Importantly, participatory governance does not eliminate the need for technical expertise, but embeds such expertise within deliberative processes that make normative assumptions explicit and contestable (Barandiaran et al. 2024).

3.5. Deliberative Affordances by Design

The fifth principle highlights the political significance of design choices. Digital interfaces and participatory devices are not neutral; they actively configure possibilities for action, interaction, and influence (Winner 1980). From a deliberative perspective, platforms should intentionally incorporate affordances that support reason-giving, reflection, and collective problem-solving (Habermas 1996; Dryzek 2000).

Such affordances may include structured proposal processes, spaces dedicated to argumentation, mechanisms for amendment and compromise, and transparent links between participation and institutional decision-making (Nabatchi and Leighninger 2015; Shin 2024). By shaping participation through deliberative workflows rather than unstructured streams of interaction, platforms can facilitate learning, reduce polarisation, and strengthen the connection between public discourse and democratic outcomes (Mansbridge et al. 2012; Fung 2015).

Together, these five principles articulate a normative architecture for alternative participatory platforms conceived as public-interest infrastructures. They provide the analytical framework through which the case of Decidim is examined in the sections that follow.

4. Methodology

This article adopts a qualitative, theory-driven case study methodology to examine the democratic potential of alternative digital participatory platforms. The methodological approach is grounded in the assumption that the democratic quality of communication infrastructures cannot be adequately assessed through quantitative indicators alone, but requires an interpretive analysis of institutional design, governance arrangements, and communicative affordances in light of normative democratic principles (Fung and Wright 2003; Mansbridge et al. 2012).

Rather than aiming at statistical generalisation, the study pursues analytical generalisation by identifying mechanisms, design principles, and institutional conditions that are relevant for evaluating participatory digital infrastructures as public-interest goods (Fung and Wright 2003). This approach is particularly appropriate for research questions that concern normative alignment, democratic legitimacy, and institutional design, rather than behavioural effects or policy outcomes.

4.1. Research Design and Case Selection

The research is designed as a qualitative case study focusing on Decidim, an open-source participatory platform originally developed by the Barcelona City Council (Barcelona City Council 2023). Decidim was selected through purposive sampling because it represents a paradigmatic example of a participatory infrastructure explicitly conceived as a democratic and public-interest platform (Barandiaran et al. 2019, 2024). It combines several features that are analytically relevant for the purposes of this study: institutional embedding within public authorities, open-source development, explicit normative commitments to deliberative democracy, and participatory governance of rules and technical evolution (Barandiaran et al. 2024; Borge et al. 2022).

Case study methodology is particularly suitable for analysing complex socio-technical arrangements that cannot be meaningfully isolated from their institutional and political contexts. In this sense, Decidim is not treated as a representative case in a statistical sense, but as an analytically rich case that enables the examination of how deliberative principles can be operationalised through concrete design choices and governance mechanisms (Fung and Wright 2003).

4.2. Materials and Sources of Analysis

The empirical materials analysed in this study consist of three main categories of sources.

First, the analysis draws on official documentation produced by the Decidim project, including white papers, governance documents, technical documentation, and community guidelines (Decidim n.d.-d, n.d.-e, n.d.-f). These materials provide insight into the platform’s normative foundations, institutional arrangements, and declared design principles.

Second, the study incorporates peer-reviewed academic literature analysing Decidim’s development, governance, and implementation in different institutional contexts (Barandiaran et al. 2019, 2024; Borge et al. 2022; Monterde et al. 2021). This literature enables the triangulation of project documentation with external scholarly assessments and situates the case within broader debates on democratic innovation and civic technology (Nabatchi and Leighninger 2015; Shin 2024).

Third, the analysis includes qualitative observation of platform functionalities, participatory workflows, and deliberative affordances as described in publicly accessible instances of the platform (Decidim n.d.-b, n.d.-c). Attention is given to how participation is structured across different stages of the participatory process, how contributions are rendered visible, and how links between public input and institutional decision-making are operationalised (Barandiaran et al. 2024).

4.3. Analytical Strategy and Methods

The analytical strategy combines several complementary scientific methods commonly employed in qualitative social research and normative institutional analysis.

First, analysis is used to decompose Decidim’s institutional and technical architecture into analytically relevant dimensions, including governance structures, participatory workflows, transparency mechanisms, and affordances for reason-giving, amendment, and accountability (Barandiaran et al. 2024; Decidim n.d.-f).

Second, synthesis is employed to integrate empirical observations with a coherent normative framework derived from deliberative democratic theory (Habermas 1996; Dryzek 2000). This involves relating platform features and governance arrangements to deliberative principles such as inclusion, publicity, reciprocity, and reason-giving, thereby enabling an evaluative assessment of democratic quality (Mansbridge et al. 2012).

Third, deduction plays a central role insofar as deliberative principles articulated in the theoretical literature function as analytical criteria against which the case is examined (Habermas 1996; Cohen 1989; Dryzek 2000). These principles provide normative benchmarks for assessing whether and how the platform’s design and governance align with the requirements of deliberative democracy.

Fourth, induction is used to identify emergent mechanisms and practices that are not fully specified by the theoretical framework but become visible through close examination of the case (Barandiaran et al. 2024; Borge et al. 2022). Examples include the role of MetaDecidim as a space for governing technical development through participatory deliberation, and the institutionalisation of traceability mechanisms linking public input to administrative response (Decidim n.d.-e).

Finally, comparison is employed implicitly by contrasting Decidim’s design and governance model with the dominant logic of commercial social media platforms as described in the literature on platform capitalism and algorithmic governance (Srnicek 2017; Zuboff 2019; Pasquale 2015). This comparative perspective highlights how alternative institutional and technical arrangements generate distinct democratic affordances (Helberger 2020).

4.4. Scope and Limitations

The methodological approach adopted in this article has clear limitations. The study does not aim to measure participation rates, deliberative quality, or policy impacts through quantitative indicators, nor does it claim causal generalisation regarding the effects of platform design on political behaviour. Instead, it focuses on the plausibility, coherence, and normative significance of design choices and governance arrangements from a deliberative democratic perspective (Fung and Wright 2003; Mansbridge et al. 2012).

The findings should therefore be understood as analytically and normatively informative rather than empirically exhaustive. Future research could complement this approach through comparative case studies across different national and institutional contexts, mixed-method designs combining qualitative and quantitative data, or longitudinal analyses of specific participatory processes implemented through Decidim (Shin 2024; Cardullo 2025).

This study relies exclusively on publicly available documentation and platform functionalities and does not involve human subjects or personal data. The analysis follows established ethical standards of transparency, accuracy, and responsible interpretation in research on digital platforms.

5. Decidim as a Democratic Infrastructure

5.1. Origins and Institutional Positioning

Decidim (Catalan for “we decide”) emerged in Barcelona as part of a broader agenda of democratic innovation, open government, and participatory governance pursued by the Barcelona City Council during the 2015–2019 municipal mandate (Barcelona City Council 2023). The platform was conceived as a digital infrastructure capable of supporting structured participatory processes, including public consultations, citizens’ assemblies, participatory budgeting, and collaborative policy-making (Decidim n.d.-f; Nabatchi and Leighninger 2015). From its inception, Decidim was framed not merely as a technical tool, but as an institutional mechanism designed to strengthen democratic participation and enhance transparency in public decision-making (Barandiaran et al. 2019, 2024).

A defining feature of Decidim is its explicit orientation towards public interest and democratic governance. Unlike corporate social media platforms, Decidim is not driven by advertising, data monetisation, or behavioural profiling (Zuboff 2019; Srnicek 2017). It was developed as open-source software and embedded within public institutions, with the explicit aim of mediating participation between citizens and decision-makers (Barcelona City Council 2023; Decidim n.d.-a). This institutional positioning distinguishes Decidim from commercial platforms whose primary function is communicative exchange without formal links to decision-making authority (Gillespie 2018).

Following its initial deployment in Barcelona, Decidim was re-engineered as a modular and reusable open-source platform, enabling its adoption by other municipalities, regional governments, universities, civil society organisations, and transnational networks (Decidim n.d.-b). This diffusion model is significant: rather than scaling through market dominance or venture-capital expansion, Decidim spreads through networks of public institutions and civic organisations that adapt the platform to local legal, political, and cultural contexts (Barandiaran et al. 2024; Cardullo 2025).

Academic analyses have described Decidim as a technopolitical infrastructure that combines institutional participation, open-source development, and democratic governance, positioning the platform as a collectively governed digital commons rather than a proprietary system (Barandiaran et al. 2019, 2024; Monterde et al. 2021). This characterisation underscores the importance of treating participatory platforms as shared public infrastructures whose legitimacy derives from democratic design and governance rather than private ownership or market success (Fung 2015; Mansbridge et al. 2012).

According to publicly available data, Decidim is currently deployed in dozens of countries across Europe, Latin America, and beyond, supporting hundreds of participatory processes and engaging hundreds of thousands of registered participants (Decidim n.d.-b). While the scale and impact of these deployments vary considerably, the platform’s international diffusion highlights its relevance as a reference case for debates on democratic digital infrastructures (Shin 2024).

5.2. MetaDecidim: Participatory Governance of the Platform

One of the most distinctive features of Decidim is MetaDecidim, the participatory governance space through which the platform itself is collectively governed (Decidim n.d.-e; Barandiaran et al. 2024). While Decidim operates as an infrastructure enabling participatory processes for public institutions, MetaDecidim functions at a meta-level, allowing the community of users, developers, researchers, and institutional representatives to deliberate on the platform’s rules, principles, and technical evolution (Barandiaran et al. 2024).

This arrangement directly addresses a central democratic deficit of corporate platforms: the unilateral governance of algorithms, moderation policies, and design choices by private actors (Gillespie 2018; Helberger 2020). In the case of Decidim, proposals for changes to the platform can be submitted, debated, amended, and justified through participatory processes that mirror the deliberative logic promoted by the platform in institutional contexts (Decidim n.d.-e; Mansbridge et al. 2012). Governance of the infrastructure thus becomes itself an object of public reasoning (Habermas 1996; Dryzek 2000).

Through MetaDecidim, participants can raise issues concerning functional developments, ethical principles, transparency standards, accessibility requirements, or the organisational structure of the Decidim Association (Decidim n.d.-e). These proposals follow structured deliberative workflows, including discussion, amendment, and decision, thereby institutionalising deliberation over the conditions of deliberation (Barandiaran et al. 2024). Technical expertise remains essential, but it is embedded within processes of public justification and contestability rather than insulated within technocratic decision-making (Bignami 2022).

Scholarly analyses have identified this meta-governance arrangement as a distinctive feature of Decidim, insofar as it institutionalises democratic control over technical development and mitigates governance deficits commonly associated with commercial platforms (Barandiaran et al. 2024; Monterde et al. 2021). By subjecting design choices and infrastructural rules to participatory deliberation, Decidim exemplifies how digital infrastructures can be governed as democratic commons rather than opaque systems of private control (Fung 2015).

5.3. Transparency, Workflows, and Traceability

Decidim’s institutional and technical architecture contrasts with the opacity of corporate platforms in several key respects. First, as open-source software, it enables inspection, independent auditing, and reuse (Barandiaran et al. 2024). Second, it structures participatory processes through clearly defined and transparent stages—such as proposal submission, discussion, amendment, and decision—making procedural workflows visible to participants (Decidim n.d.-f). Third, it places strong emphasis on traceability, enabling users to follow proposals over time and to observe how public input is processed and translated into institutional outcomes (Decidim n.d.-b).

These features operationalise deliberative principles of publicity and reason-giving (Habermas 1996; Dryzek 2000). Participants are not only able to express preferences or opinions, but can also observe how contributions are evaluated, modified, accepted, or rejected. Importantly, institutions are encouraged to provide explicit reasons when proposals are altered or dismissed, thereby fostering accountability and learning rather than frustration and cynicism (Fung 2015; Nabatchi and Leighninger 2015).

By contrast, corporate social media platforms typically organise visibility and relevance through opaque algorithmic ranking systems, offering limited insight into how content circulates or why certain contributions gain prominence (Pasquale 2015; Helberger 2020). Decidim’s emphasis on procedural transparency and traceability thus represents a deliberate attempt to reconfigure the relationship between participation, power, and accountability in digital environments (Barandiaran et al. 2024).

6. Deliberative Affordances in Practice

6.1. Structured Participatory Processes

Decidim organises participation through configurable process modules that structure interaction across identifiable stages. A typical participatory workflow includes proposal submission, public discussion, amendment or merging of proposals, prioritisation or voting, and institutional decision-making accompanied by implementation tracking (Decidim n.d.-b, n.d.-f). This sequential organisation distinguishes Decidim from unstructured communicative environments characteristic of corporate platforms (Helberger 2020; Gillespie 2018).

From a deliberative perspective, this structure is significant because it transforms participation from a continuous stream of comments into a process oriented towards collective outcomes (Habermas 1996; Dryzek 2000). By providing clear stages and expectations, the platform supports reflection, learning, and coordination among participants, while also clarifying the role of institutions in responding to public input (Fung 2015; Nabatchi and Leighninger 2015).

6.2. Reason-Giving and Argumentative Exchange

Decidim provides dedicated deliberative spaces attached to proposals and participatory processes, enabling participants to articulate reasons, respond to counterarguments, and engage in structured discussion (Decidim n.d.-f). While the quality of deliberation depends on facilitation and institutional context, the platform’s design offers explicit venues for argumentative exchange rather than privileging performative visibility or emotional amplification (Habermas 1996; Dryzek 2000).

Crucially, visibility within these spaces is not primarily organised through engagement-driven ranking algorithms. This reduces incentives for outrage-driven communication and strategic manipulation, thereby supporting conditions more conducive to reasoned debate and mutual understanding (Helberger 2020; Pasquale 2015).

6.3. Amendment, Compromise, and Co-Production

A central deliberative affordance of Decidim is the possibility to amend proposals and merge overlapping initiatives (Decidim n.d.-f; Barandiaran et al. 2024). This feature enables participants to move beyond binary choices of support or rejection and to engage in processes of compromise and co-production (Dryzek 2000). Through amendment mechanisms, proposals can be refined to incorporate concerns related to feasibility, inclusiveness, cost, or institutional constraints (Nabatchi and Leighninger 2015).

From a deliberative standpoint, such mechanisms are crucial for transforming participation into collective problem-solving. They support learning, reduce polarisation, and enhance the legitimacy of outcomes by documenting how proposals evolve through public reasoning (Mansbridge et al. 2012; Fung 2015).

6.4. Traceability and Institutional Accountability

Decidim’s traceability mechanisms explicitly link public input to institutional response (Decidim n.d.-b). Proposals are assigned public statuses—such as under review, accepted, or rejected—and institutions are encouraged to provide justifications for their decisions. This creates accountability expectations that are often absent in digital participation initiatives (Fung 2015; Nabatchi and Leighninger 2015).

By making institutional responses visible and reasoned, the platform enables citizens to evaluate responsiveness, understand constraints, and contest decisions through argument rather than suspicion (Habermas 1996; Dryzek 2000). From a deliberative perspective, this strengthens the legitimacy of participation by connecting discourse to decision-making in a transparent and accountable manner (Mansbridge et al. 2012).

6.5. Hybrid Participation and Institutional Integration

Finally, Decidim supports hybrid participation by integrating offline events—such as assemblies, workshops, and public meetings—into digital participatory processes (Decidim n.d.-b, n.d.-f). Agendas, minutes, and outcomes of offline deliberation can be published on the platform, enabling continuity between face-to-face discussion and online engagement (Nabatchi and Leighninger 2015).

This integration enhances inclusion by lowering barriers to participation and mitigating digital divides, while also reinforcing the embeddedness of digital participation within local institutional and civic contexts (Fung 2015; Shin 2024). By connecting online and offline deliberation, Decidim contributes to a more integrated and resilient participatory ecosystem (Mansbridge et al. 2012).

7. Discussion

The case of Decidim provides a theoretically and empirically grounded basis for discussing the democratic implications of platform design and governance in the contemporary digital public sphere. Rather than treating digital infrastructures as neutral intermediaries, the analysis confirms that platforms exercise a form of structural power by shaping visibility, participation, and the conditions under which public reasoning becomes possible (Helberger 2020; Gillespie 2018). This insight resonates with recent scholarship emphasising that platforms govern public discourse not only through content moderation, but also—and more fundamentally—through design choices embedded in technical and institutional architectures (Gillespie 2018; Helberger 2020).

From a deliberative democratic perspective, Decidim illustrates how alternative institutional and technical arrangements can partially counteract the democratic deficits associated with commercial social media platforms (Habermas 2022; Zuboff 2019). Features such as transparent participatory workflows, mechanisms for amendment and co-production, traceability of proposals, and participatory governance of rules and infrastructure directly address core deliberative requirements, including publicity, reciprocity, reason-giving, and accountability (Habermas 1996; Dryzek 2000; Barandiaran et al. 2024). In this sense, Decidim does not merely enable participation in a procedural sense; it actively structures the conditions of deliberation (Mansbridge et al. 2012).

Importantly, the analysis supports the argument that algorithmic systems are not inherently incompatible with democratic norms. While dominant platforms operationalise algorithmic rationality in ways that privilege engagement maximisation and emotional amplification (Helberger 2020; Pasquale 2015), Decidim demonstrates that algorithmic and procedural logics can be oriented towards civic purposes and public value (Fung 2015; Nabatchi and Leighninger 2015). This observation aligns with recent research in public administration and digital government, which highlights the potential of digital technologies to enhance transparency, responsiveness, and institutional learning when embedded within appropriate governance frameworks (Shin 2024; Cardullo 2025).

From a broader governance perspective, Decidim can also be interpreted as part of a wider landscape of participatory and experimental governance arrangements that have emerged in recent years within urban and public-sector contexts (Sabel and Zeitlin 2012; Evans et al. 2016; Voytenko et al. 2016). Research on participatory governance, urban experimentation, and so-called living labs emphasises how digital and institutional innovations often function as iterative, learning-oriented processes rather than as fully stabilised models (Sabel and Zeitlin 2012; Voytenko et al. 2016). Viewed through this lens, Decidim should be understood not as a universally transferable solution, but as an exemplary and theory-informed case of institutional experimentation, whose democratic effects remain contingent upon political commitment, administrative capacity, and local governance cultures (Borge et al. 2022; Barandiaran et al. 2024). This perspective further reinforces the need to analyse participatory infrastructures as evolving socio-technical arrangements embedded in specific institutional ecologies (Evans et al. 2016).

At the same time, the Decidim case highlights the limits of technological solutions to democratic challenges. Deliberative affordances do not automatically generate deliberative outcomes. Empirical studies of Decidim’s use across different municipalities indicate significant variation in its democratic impact, depending on political commitment, administrative capacity, facilitation practices, and legal frameworks (Borge et al. 2022). In some contexts, Decidim functions as a robust deliberative infrastructure with tangible influence on decision-making; in others, it operates primarily as a consultation or transparency tool with limited institutional consequences (Borge et al. 2022; Shin 2024).

This variation underscores a central insight of systemic approaches to deliberative democracy: democratic legitimacy emerges from the interaction of multiple arenas and institutions rather than from isolated platforms (Mansbridge et al. 2012). Digital participatory infrastructures must therefore be understood as components of broader institutional ecologies. Their democratic effects depend on how they are articulated with representative institutions, legal mandates, administrative routines, and political cultures (Fung 2015; Nabatchi and Leighninger 2015).

Recent debates on artificial intelligence and automated decision-support systems in public administration further reinforce this point. While AI may enhance efficiency and administrative capacity, it also raises concerns regarding transparency, explainability, accountability, and public trust (Bignami 2022; Aoki 2024). From a deliberative perspective, these concerns highlight the importance of ensuring that algorithmic systems remain subject to public justification and institutional oversight (Habermas 1996; Bignami 2022). In this regard, participatory platforms such as Decidim offer a relevant contrast to opaque forms of algorithmic governance by embedding digital decision-support within deliberative and accountable institutional frameworks (Barandiaran et al. 2024; Aoki 2024).

Several limitations of this study should be acknowledged. First, the analysis is based on a single qualitative case study and does not claim causal generalisation regarding the effects of deliberative platform design on political behaviour or policy outcomes (Fung and Wright 2003). Second, the study relies on documentary analysis and qualitative observation rather than direct user data or quantitative measures of deliberative quality. Third, the focus on normative principles may underplay informal dynamics, power asymmetries, and strategic behaviour that shape participation in practice (Mansbridge et al. 2012).

Future research could address these limitations by adopting comparative case studies across different national and institutional contexts, combining qualitative and quantitative methods, or analysing longitudinal data on specific participatory processes. Further work is also needed to examine how emerging forms of artificial intelligence interact with deliberative principles in public administration, particularly with regard to transparency, contestability, and democratic accountability (Bignami 2022; Aoki 2024; Shin 2024).

8. Conclusions

This article set out to examine how alternative digital platforms can be designed and governed as public-interest infrastructures capable of supporting democratic deliberation in the contemporary digital public sphere. Drawing on deliberative democratic theory and a qualitative, theory-driven case study of Decidim, the analysis addressed the growing tension between communicative rationality and the dominant logic of algorithmic rationality embedded in commercial social media platforms (Habermas 1996, 2022; Pasquale 2015; Zuboff 2019).

The findings demonstrate that the democratic deficits of the digital public sphere—such as fragmentation, polarisation, opacity, and the erosion of shared horizons of meaning—are not technologically inevitable. Rather, they are closely linked to specific institutional arrangements, business models, and design choices (Helberger 2020; Zuboff 2019; Srnicek 2017). The case of Decidim shows that when participatory platforms are governed as public goods, insulated from surveillance-based monetisation, and equipped with deliberative affordances by design, digital infrastructures can support inclusion, reason-giving, accountability, and collective learning (Fung 2015; Nabatchi and Leighninger 2015; Barandiaran et al. 2024).

By operationalising principles such as public-interest governance, algorithmic transparency, civic orientation, participatory rule-making, and traceability of outcomes, Decidim illustrates how democratic values can be embedded at both institutional and technical levels (Barandiaran et al. 2024; Decidim n.d.-f). The platform’s governance model, particularly through MetaDecidim, further demonstrates that the rules and architectures shaping participation need not be imposed unilaterally, but can themselves become objects of democratic deliberation (Mansbridge et al. 2012; Habermas 1996).

At the same time, the analysis confirms that digital platforms alone cannot resolve deeper democratic challenges. Deliberative outcomes depend on broader institutional conditions, including political commitment, administrative capacity, legal mandates, and democratic culture (Borge et al. 2022; Fung 2015). Without these conditions, even well-designed participatory infrastructures risk being reduced to consultative or symbolic devices (Shin 2024). This reinforces the argument that democratic renewal in the digital age requires systemic approaches that integrate digital infrastructures into wider deliberative and representative arrangements (Mansbridge et al. 2012).

The contribution of this article is therefore twofold. Theoretically, it extends deliberative democratic theory to the infrastructural level of digital communication, highlighting the political significance of platform design and governance (Habermas 2022; Helberger 2020). Empirically, it provides a grounded analysis of Decidim as an existing alternative to corporate social media platforms, demonstrating the feasibility of democratically governed participatory infrastructures (Barandiaran et al. 2024; Borge et al. 2022).

In conclusion, the reconstruction of digital platforms as democratic infrastructures should be understood as a central task for contemporary democracies. This entails sustained public investment, institutional innovation, and a reconceptualisation of digital technologies not as neutral tools or private commodities, but as domains of democratic governance and collective responsibility (Fung 2015; Habermas 1996; Bignami 2022).